Annual Meeting 2016 - Lyon: Poster Abstracts

The schedule and abstracts can be downloaded as a pdf:  Annual Meeting 2016 - Abstracts Booklet

Life on a rocky shoreline: a new view of Ediacaran palaeobiology

*Peter W. Adamson and Nicholas J. Butterfield

University of Cambridge, UK

The Ediacaran is marked by a distinctive assemblage of large acanthomorphic acritarchs, best known from the Doushantuo Formation in South China.  These fossils offer the only reasonable prospect for biostratigraphic subdivision of the early Ediacaran, though such potential seems compromised by their restriction to localized low-energy environments in chert, phosphorite, and mudstone facies.  Our study of the interstices of a debris-flow conglomerate in the Ediacaran Biskopås Formation (Norway) finds conglomerate palaeosurfaces encrusted with phosphatized microbial mats containing trapped acanthomorphs.  Additionally, conglomerate interstices filled with micrite (now recrystallized to microsparite) preserve ten acanthomorph species – the first documented occurrence of Doushantuo-type acritarchs preserved in carbonate.  Sedimentological and palaeontological reconstruction of the Biskopås facies demonstrates that the acanthomorph-forming organisms were living in direct proximity to the actively prograding conglomerate.  The discovery of carbonate-hosted acanthomorphs in a high energy environment alludes to a highly recalcitrant and eurytopic nature within shallow waters, and their possible function as the resting cysts of protists.  These novel windows reveal for the first time the development of eukaryotic ecosystems along rocky coastlines during a period of major ecological and evolutionary innovation in the terminal Proterozoic, while expanding the utility of such fossils in biostratigraphically partitioning the early Ediacaran.

A new juvenile burnetiamorph (Therapsida: Biarmosuchia) skull from the Beaufort Group, South Africa and its role in a revision of Lemurosaurus pricei

Duhamel Aliénor¹, Julien Benoit², Michael O. Day² and Bruce S. Rubidge²

¹CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
²University of the Witwatersrand, South Africa

The skull of a small burnetiamorph (Therapsida: Biarmosuchia) was recently discovered in the collections of the Council for Geoscience, Pretoria.  The specimen (CGP MJF 22) was originally collected in the Victoria West district of Western Cape Province, South Africa, in the Pristerognathus Assemblage Zone (latest Guadalupian, ~260 Ma) of the Main Karoo Basin.  Despite a number of new descriptions over the last 13 years, the relationships within Burnetiamorpha remain poorly understood, partly because the rarity of individual taxa and high morphological variability hinder the recognition of ontogenetic signatures.  CGP MJF 22 has large orbits compared to the reduced size of the skull, clearly defined sutures and an un-ossified braincase and bony labyrinth, which together suggest that it is a juvenile.  This provides an opportunity to understand growth trends in Burnetiamorpha.  The juvenile specimen is similar to Lemurosaurus pricei; the holotype (an adult) and CGP MJF 22 are similar in size, yet the juvenile characteristics of CGP MJF 22 (lesser development of the supraorbital bosses, absence of a frontal crest or zygomatic bosses) suggest that it is not conspecific.  We provide a revision of the taxon Lemurosaurus pricei and in particular suggest the reassignment of referred specimen NMQR 1702.

Upper Famennian ammonoids from the Ougarta Basin (Saoura Valley, Algeria)

*Ninon Allaire¹, Claude Monnet¹, Abdelkader Abbache² and Catherine Crônier¹

¹CNRS UMR 8198, Université de Lille, France
²Université de Mascara, Algeria

The Famennian (Upper Devonian) deposits record several hypoxic events such as the global Annulata Event(s).  These deposits outcrop in various regions of the world and often contain rich ammonoid faunas, which can be used to biostratigraphically constrain these events.  The present study contributes to the description of the Upper Devonian ammonoids in Algeria, especially from the Saoura Valley.  Although Upper Devonian deposits in this area were first recognized on the basis of cephalopods more than one century ago, they remain poorly studied.  This study is the first comprehensive description of newly collected, abundant material from the Marhouma Formation in several sections around Beni Abbès.  In the Saoura Valley (Ougarta Basin), the Famennian part of the Marhouma Formation is characterised by deep-water facies including levels rich in ammonoids.  In the Ouarourout area the ammonoid faunas are represented by 16 genera belonging to 11 families: Sporadoceratids (Sporadoceras and Erfoudites), Prionoceratids (Prionoceras), Tornoceratids (Planitornoceras and Gundolficeras), Posttornoceratids (Discoclymenia), Cyrtoclymeniids (Cyrtoclymenia), Cymaclymeniids (Procymaclymenia, Cymaclymenia and Genuclymenia), Platyclymeniids (Platyclymenia), Clymeniids (Clymenia), Kosmoclymeniids (Muessenbiaergia and Kosmoclymenia), Sphenoclymeniids (Sphenoclymenia) and Gonioclymeniids (Gonioclymenia).  This ammonoid assemblage can be correlated with ammonoid faunas from the well-known Tafilalt area (Morocco) and corresponds to the Platyclymenia annulata Zone (upper Famennian, UD.IV-A).

Endocranial anatomy of two Elasmosauridae specimens (Reptilia, Plesiosauria) from the Late Cretaceous of Morocco

Rémi Allemand¹, Nathalie Bardet¹, Alexandra Houssaye² and Peggy Vincent¹

¹CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
²CNRS UMR 7179, Muséum National d’Histoire Naturelle, France

Elasmosaurs were a group of marine plesiosaurians that lived during the Cretaceous period.  They were agile swimmers and presumably active predators.  Although the adaptations of elasmosaurs to the aquatic realm have been extensively studied from the post-cranial skeleton, the sensorial abilities supporting their adaptation to a fully aquatic lifestyle are still poorly understood.  Here we present the description of CT scan-generated endocasts of two elasmosaur specimens from the Turonian of Goulmima (Morocco) in order to improve our understanding of their endocranial anatomy as well as their behaviour and sensorial adaptations.  Results of the segmentation reveal enlarged optic bulbs and cerebellum suggesting neuroanatomical adaptations, allowing them to be highly mobile with developed visual capacities.  The thin and long olfactory tracts do not allow interpretation of whether the specimens possessed chemoreception.  The two specimens exhibit also a reduced inner ear, with small and thick semi-circular canals, as well as a bulbous vestibule, in accordance with previous observation of sensory adaptation in secondarily adapted marine tetrapods.

One head with two bodies: the Onaraspis–Myopsolenites trilobite conundrum

J. Javier Alvaro¹, Jorge Esteve², Fernando Gracia³ and Samuel Zamora⁴

¹Instituto de Geociencias (CSIC UCM), Spain
²Complutense University of Madrid, Spain
³Independent
⁴Instituto Geológico y Minero de España, Spain

A new fossil assemblage of Cambrian Epoch 2 (early Cambrian) redlichiid trilobites has been found in the Huérmeda Formation of the Iberian Chains, northeast Spain.  This assemblage is dominated by complete specimens characterised by macropleura-bearing thoraxes close to the genera Onaraspis Öpik, 1968 and Myopsolenites Geyer and Landing, 2004, the former reported from Australia and the latter from the Mediterranean and Polish margins of Gondwana.  Despite their cephalic similarities, these taxa display highly diversified thoraxes and shield-like pygidia.  Although the number of segments in the trunk and the proportions allocated to the thorax and pygidium varied with ontogeny, several Iberian genera and species can be taxonomically differentiated based on trunk features.  Cambrian diversification not only featured evolutionary ‘experiments’ with the constructional framework for the trilobite cephalon, but also for the trilobite trunk.  The Cambrian diversification in the development of the trunk represents a wakeup call for taxonomic analyses exclusively based on disarticulated cranidia, and highly controlled by taphonomic biases.

A palynological investigation of the Middle Devonian of northern Spain: hunting for the Kačák event

*Alexander Askew and Charles H. Wellman

University of Sheffield, UK

Northern Spain contains an exceptionally complete Devonian sequence, chronicling widely varying depositional environments in a Peri-Gondwana setting.  We describe palynomorph assemblages from the Eifelian and Givetian age Huergas, Naranco and Gustalapiedra Formations from Asturias, Castilla y León and Palencia provinces, respectively.  These laterally equivalent formations represent a transect from shallow nearshore to deep offshore shelf deposits.  Sandwiched between thick limestone sequences, these formations consist of large sandstone bodies interspersed with black shales, representing a period of greatly increased terrigenous input to the ocean.  Samples have yielded rich assemblages of land-derived spores and marine palynomorphs (acritarchs, chitinozoans and occasional scolecodonts).  Preliminary results of the quantitative analysis of this material are presented, which ultimately aim to age-constrain the formations and reveal temporal and spatial changes in the terrestrial and marine communities.  A further aim is to identify any influence of the contemporary Kafont-family:TimesNewRomanPSMT'>čák event.  This widely occurring anoxic event is associated with marine extinctions and faunal turnover, though it is poorly characterised in Iberia, and its effect on terrestrial floras is little-known.  We hope to identify the Kačák event in northern Spain and document its effect on the local biota, thus shedding light on potential causes of this event.

Brachiopod shell thickness and the End-Ordovician mass extinction

Uwe Balthasar

Plymouth University, UK

Calcareous brachiopods are among the most diverse, abundant, and best studied groups of early Palaeozoic fossils.  By contrast to overall shell morphology, which has a long tradition of careful systematic study, shell thickness of brachiopods is commonly treated superficially and non-quantitatively.  Here I present the first systematic study of shell thickness for brachiopods.  The study looked at 181 shells of Ordovician–Silurian rhynchonelliformean brachiopods and reveals a distinct morphospace of shell thickness and shell length.  When normalised for maximum shell thickness, this morphospace reveals significant differences on an order level with orthids and strophomenids having significantly thicker shells than rhynchonellids and pentamerids.  The latter group is unusual in that they combine a very thick posterior shell with a paper-thin anterior shell covering the filtration chamber.  Genus-level occurrence data from the Paleobiology Database show that the two thicker-shelled orders declined significantly during the End-Ordovician mass extinction whereas occurrences of thinner-shelled orders increased.  This suggests that a more economical way of shell secretion might have been advantageous during the end-Ordovician mass extinction.

Emergence of the modern freshwater food web in the early Carboniferous

Carys E. Bennett¹, Sarah J. Davies¹, Timothy I. Kearsey², David Millward², Timothy R. Smithson³, Jennifer A. Clack³, Peter Brand², Andrew J. Ross⁴, Neil D. L. Clark⁵ and Marcello Ruta⁶

¹University of Leicester, UK
²British Geological Survey, UK
³University of Cambridge, UK
⁴National Museums Scotland, UK
⁵The Hunterian, University of Glasgow, UK
⁶University of Lincoln, UK

Freshwater ecosystems underwent a renovation after the extinction of many fish groups during the Hangenberg crisis.  Carboniferous tetrapods, actinopterygians, dipnoans, gyracanthids and chondrichthyans occupied the niches left vacant by placoderms and porolepiformes.  Change to invertebrate community structure also occurred, with bivalves and ostracods radiating from marine to freshwater environments.  Little is known about changes in food webs during this transition, or vertebrate–invertebrate interactions.  The radiation of ostracods and bivalves into fresh water initiated a modern food web structure and may have contributed towards the rapid diversification of many vertebrate groups.  The sandy siltstone facies of the Tournaisian Ballagan Formation of Scotland was deposited in temporary floodplain lakes and contains a rich aquatic and terrestrial fauna that is populating Romer’s Gap.  The faunal associations of sandy siltstone beds (n = 122), coupled with literature data (e.g. gut contents) are used to reconstruct the freshwater food web: producers comprise algae and terrestrial plant matter, consumed by ostracods, spinicaudatans and mytilid and myalinid bivalves.  Second order consumers include eumalacostracans, actinopterygians, dipnoans and eurypterids, predated by gyracanthids, rhizodonts, chondrichthyans and tetrapods.  Morphometric analyses of dipnoan toothplates and bivalve shells are used to infer possible dietary associations.

Cryptic biocoenoses from the Middle Devonian of Morocco

Blazej Berkowski¹, Michal Jakubowicz¹, Zdzislaw Belka¹, Mikolaj K. Zapalski² and Jan J. Krol¹

¹Adam Mickiewicz University in Poznań, Poland
²University of Warsaw, Poland

Three exceptionally well-preserved fossil cryptic communities composed of rugose corals and other sessile invertebrates were discovered in submarine cavities of the Middle Devonian (Givetian) mud-mound in the Hamar Laghdad area (Morocco).  The studied cryptic biota is dominated by small solitary rugose corals, which encrusted the roofs of the cavities and grew predominantly in an inverted position with ‘calice-in-calice’ growth.  Different cavities were settled by different communities of solitary rugose taxa.  The rugose corals identified in the studied cryptic palaeoecosystems also occur outside of the cavities, within mound facies and/or well-bedded intermound deposits of the Givetian of the Hamar Laghdad area.  The results support the hypothesis that during the middle Palaeozoic there was no distinct polarization between open-surface and cryptic faunas in relatively deep-water environments.  Different taxonomic compositions of the studied cryptic ecosystems show that the regional species pool was the main determinant of the structure of these assemblages.  The high density of organisms growing on each other indicates that intensive competition for space must have already existed in Devonian submarine crypts.  All these observations show that the studied cryptic assemblages differed markedly from both their Palaeozoic and modern analogues.

The family Lonchidiidae in the Early Cretaceous record of Spain

*David D. Bermúdez-Rochas

Complutense University of Madrid, Spain

The family Lonchidiidae Herman, 1977 (Hybodontoidea) was widespread in Mesozoic non-marine environments in western Europe during the Early Cretaceous, being one of the most common hybodont sharks in the Spanish fossil record at this time.  Remains of this family have been identified in almost all of the major Early Cretaceous Spanish sites.  Apart from scarce articulated specimens from the Lagerstätte of La Pedrera de Rúbies (Montsech, Lleida, South-Central Pyrenees), hundreds of isolated remains of these sharks are commonly found in the rest of the Iberian Peninsula, with an Early Cretaceous palaeogeographical distribution that ranges from the Basque–Cantabrian Basin (connected to the Boreal Ocean), through all along the Iberian Basin, connected to the Alpine Tethys Ocean.  Despite the abundance of lonchidiid remains (most of them teeth), the problems inherent to the parataxonomy and the scarcity of studies related to these faunas in Spain have, in most cases, prevented their proper taxonomic assignation.  The study of new abundant hybodont faunas from the Enciso Group (Early Aptian, Cameros Basin) and the revision of the type material of the Spanish species Lonchidion microselachos and the classic European taxon ‘Hybodus’ parvidens have permitted a new understanding of the dentition patterns of both species.

Inferring the diets of pterosaurs and extant analogues using quantitative 3D textural analysis of tooth microwear

*Jordan Bestwick¹, David M. Unwin¹, Mark A. Purnell¹, Richard J. Butler² and Donald M. Henderson³

¹University of Leicester, UK
²University of Birmingham, UK
³Royal Tyrrell Museum, Canada

Pterosaurs were a successful group of Mesozoic flying reptiles.  For 150 million years they were integral components of terrestrial and coastal ecosystems, yet their feeding ecology remains poorly constrained.  Postulated pterosaur diets include insectivory, piscivory and/or carnivory, but many dietary hypotheses are speculative and/or based on little evidence, highlighting the need for alternative approaches to provide robust data.  One method involves quantitative analysis of the micron-scale 3D textures of worn pterosaur tooth surfaces – dental microwear texture analysis.  Microwear is produced as scratches and chips generated by food items create characteristic tooth surface textures.  Microwear analysis has never been applied to pterosaurs, but we might expect microwear textures to differ between pterosaurs with different diets.  An important step in investigating pterosaur microwear is to examine microwear from extant organisms with known diets to provide a comparative data set.  This has been achieved through analysis of non-occlusal microwear textures in extant bats and crocodilians, clades within which species exhibit insectivorous, piscivorous and carnivorous diets.  The results – the first test of the hypothesis that non-occlusal microwear textures in these extant clades vary with diet – provide the context for the first robust quantitative tests of pterosaur diets.

Reinvestigation of Protelytron permianum (Insecta; Early Permian; USA) as an example for applying reflectance transformation imaging to insect imprint fossils

Olivier Béthoux¹, Artémis Llamosi^2,3 and Séverine Toussaint^1,2

¹CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
²CNRS UMR 7057, Sorbonne Universités, France
³INRIA Saclay, France

We reinvestigated the holotype of Protelytron permianum, one of the earliest putative stem-dermapteran (i.e. stem-earwig).  We used reflectance transformation imaging (RTI) to produce exhaustive and interactive photographic data of the specimen.  We identified broadenings located along veins of the hind wing vannus that form an arc, in addition to a series of radiating folds, alternatively concave and convex.  Such an organization is diagnostic of Dermaptera and reflects hind wing folding mechanisms, which are particularly elaborated in these insects.  We provide a foldable, paper model of the hind wing.  Based on the case presented herein we anticipate that RTI-aided approaches will provide critical new data on the morphology of fossil insects preserved as imprints.

A timescale for life’s early evolution: is it time to leave behind a literal interpretation of the fossil record?

*Holly Betts, Tom A. Williams, Philip C. J. Donoghue and Davide Pisani

University of Bristol, UK

The timescale of life’s early history on Earth remains one of the last areas where literal interpretations of the fossil record guide our understanding.  However, the uncertainty surrounding the early fossil record of life suggests that a probabilistic timescale could serve as a better guideline.  Such a timescale can be generated by integrating fossils and genomic information using modern, relaxed, molecular clock methods.  Molecular clocks rely on carefully constructed calibrations and, to date, no definitive set of calibrations for dating fundamental divergences within the tree of life has been assembled.  Here we establish a suite of calibrations, employing them with the molecular clock to show that divergence times are sensitive to calibration distribution choice, and the clock model used.  Integrating across the uncertainties yields a timescale that defines credibility intervals for key events in the history of life.  Our probabilistic timescale, integrating fossil and genomic information, is more accurate though less precise, allowing for predictive power and simple refinements as new fossil and molecular data are revealed.  It shows the Prokaryote crown lineages appearing at a similar time prior to 3 Ga, with crown Eukaryotes a late-coming clade, established around 1.8 Ga, in correspondence with the mitochondrial precursor, the Alphaproteobacteria.

Complex post-crisis marine ecosystem during the Early Triassic

Arnaud Brayard¹, L. J. Krumenacker², Joseph P. Botting³, James F. Jenks⁴, Kevin G. Bylund⁴, Emmanuel Fara¹, Emmanuel Vennin¹, Nicolas Olivier⁵, Nicolas Goudemand⁶, Thomas Saucède¹, Sylvain Charbonnier⁷, Carlo Romano⁸, Larisa Doguzhaeva⁹, Ben Thuy¹⁰, Michael Hautmann⁸, Daniel A. Stephen¹¹, Christophe Thomazo¹ and Gilles Escarguel¹²

¹CNRS UMR 6282, Université de Bourgogne Franche Comté, France
²Montana State University, USA
³Amgueddfa Cymru - National Museum Wales, UK
⁴Independent
⁵Université Blaise Pascal, Clermont-Ferrand, France
⁶CNRS UMR 5242, Université de Lyon and Ecole Normale Supérieure de Lyon, France
⁷CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
⁸University of Zurich, Switzerland
⁹Swedish Museum of Natural History, Sweden
¹⁰National Museum of Natural History, Luxembourg
¹¹Utah Valley University, USA
¹²CNRS UMR 5023, Université de Lyon, France

In the aftermath of the end-Permian mass extinction, the Early Triassic (~251.9–247 Ma) represents an environmentally unstable time interval affected by several extinction events and characterised by poorly diversified marine benthic communities.  However, a new, exceptional fossil assemblage from the earliest Spathian (~250.6 Ma, middle Olenekian) documents a highly diversified and remarkably complex marine ecosystem, with more than 20 distinct metazoan orders including sponges, brachiopods, molluscs, arthropods, echinoderms and vertebrates.  This highly diversified assemblage represents the most complex marine ecosystem known to date for the Early Triassic.  Most unexpectedly, primitive leptomitid protomonaxonid sponges that were previously known only from Early Palaeozoic assemblages (a 200-million-year Lazarus taxon) are found together with gladius-bearing coleoid cephalopods, a common and diversified group expected to occur only since the Jurassic.  Furthermore, several taxa document the earliest occurrence of derived characters in their clades, pushing their origin or diversification much earlier than previously thought.  Overall, this remarkable biota shows that the diversity and dominance of the modern evolutionary fauna may have risen rapidly from complex post-crisis ecosystems with highly unexpected compositions at the dawn of the Mesozoic era.

Vertebral morphology and lung structure in non-avian dinosaurs; a geometric morphometric approach

*Robert Brocklehurst¹, Emma Schachner², Jonathan Codd¹, William Sellers¹ and Philip Manning³

¹University of Manchester, UK
²Louisiana State University, USA
³College of Charleston, USA

Reconstructing the respiratory system in non-avian dinosaurs is key to understanding the evolution of thermal physiology and aerobic capacity along the avian stem.  In modern sauropsids, the lung’s dorsal surface attaches to the vertebral bodies and proximal ribs; therefore, axial skeleton morphology provides a reliable osteological correlate of lung structure.  Vertebral shape and the relative positions of the rib articulations – diapophysis and parapophysis – were quantified using 2D morphometrics in a range of non-avian dinosaurs.  Living birds and crocodilians provided an extant phylogenetic bracket.  Multivariate analysis of landmark data shows clear differences in vertebral morphology, associated with different lung morphologies.  Birds have the parapophysis on the vertebral centrum, associated with a furrowed thoracic ceiling and rigid lungs incised by the proximal ribs.  In crocodilians, the parapophysis migrates laterally onto the transverse process, producing a smooth thoracic ceiling associated with compliant lungs ventilated by the hepatic piston.  Non-avian dinosaurs show an intermediate condition, and position in morphospace, where the parapophysis migrates only to the base of the transverse process.  These results suggest that dinosaurs had a heterogeneously partitioned lung, with a more rigid dorsal region and compliant ventral region, but not a completely subdivided lung-air sac system as seen in birds.

New species of early Eocene perissodactyls from Le Quesnoy (France, MP7): evolutive and biogeographic implications

Constance Bronnert¹, Emmanuel Gheerbrant¹, Marc Godinot^1,2 and Grégoire Métais¹

¹CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
²EPHE, France

Perissodactyls appear during the Paleocene–Eocene transition in the Northern Hemisphere.  Their centre of origin is still uncertain but the Asian hypothesis is generally favoured.  The locality of Le Quesnoy (Oise, France) has yielded one of the oldest and most complete fauna from the earliest Eocene of Europe (MP7).  The material is very rich (290 specimens) and well-preserved compared to other MP7 localities.  It includes dental and postcranial elements which shed new light on the early evolution of perissodactyls in Europe.  Two new species of perissodactyls from Le Quesnoy have been identified.  A new species of the hippomorph genus Pliolophus is documented by abundant dental and postcranial remains, which allow us to study the intraspecific variation and the locomotor adaptations of this species.  The second species is a new basal Tapiromorpha that shows dental similarities with the paraphyletic ‘Isectolophidae’ group.  It is the oldest occurrence of Tapiromorpha in Europe, thus suggesting a major immigration event at the base of the MP7.  The fossil material from Le Quesnoy provides a unique glimpse into the diversity and palaeobiogeography of basal perissodactyls.

Brachiopods, biomineralization and the Cambrian radiation: combined morphological and molecular systematics as a tool to infer deep lophophorate relationships

Aodhán D. Butler¹, Sandra J. Carlson² and Erik A. Sperling¹

¹Stanford University, USA
²University of California, Davis, USA

Within Lophotrochozoa, brachiopods and allied clades are among the first biomineralized Cambrian metazoans to appear and represent a major component of the oldest known fossil record of animals, as disclosed by the tommotiids, enigmatic ‘small shelly fossil’ faunas of the early Cambrian.  While the brachiopod fossil record is ultimately the key to determining character homology and polarity during the evolution of the brachiopod body plan, correctly reading this record has been clouded by disagreement about relationships among the crown clades.  Specifically, the monophyly of brachiopods with respect to phoronids, and the relationships of the calcitic-shelled to phosphatic-shelled brachiopods.  Much of this phylogenetic uncertainty stems from difficulties in rooting the tree of brachiopods, phoronids and their sister groups within the Lophotrochozoa.  To this end, we are implementing the first extensive phylogenomic investigation of extant brachiopods and phoronids, which will aid resolution of the pattern of these deep evolutionary relationships.  To date, combined analyses of fossils, morphology and molecular data support brachiopod monophyly and suggests the tommotiids are the sister group of linguliform brachiopods.  With a robust phylogenetic backbone in place to polarize morphological characters, this will illuminate the pattern of biomineral evolution within phosphatic and calcitic brachiopods during the Cambrian radiation.

First report of the Foliomena fauna in Portugal

*Jorge Colmenar¹, Sofia Pereira^2,3,4, Artur A. Sá^3,4, Carlos M. Da Silva² and Timothy P. Young⁵

¹Natural History Museum of Denmark, Denmark
²Universidade de Lisboa, Portugal
³Universidade de Trás-os-Montes e Alto Douro, Portugal
⁴Universidade de Coimbra, Portugal
⁵GeoArch, Wales.

The Foliomena fauna was first described by Sheehan (1973) from the lower Ashgill (middle Katian, Ka2 stage slice, Upper Ordovician) of Sweden.  It is dominated by small, thin-shelled brachiopods frequently associated with pelagic trilobites.  This community characterised the early-mid Katian deep-water faunas of low-mid latitude settings (Rong et al. 1999 and references), but younger records (late Katian) were also documented in higher latitudes (Havlífont-family:ArialNarrow'>ček and Mergl 1982; Villas et al. 2002).  However, up to now, the Foliomena fauna were unknown in the Iberian Peninsula.  Here we report and describe for the first time a typical Foliomena fauna assemblage from the upper Katian (regional Kralodvorian) of Portugal.  This highly diverse (~20 taxa) assemblage comes from the uppermost beds of the Porto de Santa Anna Formation (Young 1988), ranging from the middle (Ka2) to the uppermost Katian (Ka4), cropping out in several localities of the Buçaco–Penacova region (Central Iberian Zone).  It is composed of the brachiopods Jezercia, Aegiria, Christiania?, Dedzetina, Eoplectodonta (Kozlowskites), Eridorthis, Epitomyonia, Foliomena, Nicolella, Skenidioides, Ptychopleurella, Protozyga?, Bicuspina, Oxoplecia, Triplesia, Paracraniops, Rafinesquinidae indet. and the trilobites Phillipsinella, aff. Parillaenus and Cyrtometopinae indet.  A more comprehensive taxonomic study and further statistical analyses will help determine the palaeogeographic affinities of this assemblage.

Evaluating the phylogenetic consistency of morphological data for birds using molecular trees

Leah Callender-Crowe, Peter Choate and Robert Sansom

University of Manchester, UK

Morphological data are fundamental for building phylogenies and thus for interpreting evolutionary history.  Moreover, it is the only source of data available from fossil taxa.  However, morphology is beset with problems such as subjectivity, non-independence of characters and ecologically-driven convergence.  Furthermore, morphological data frequently exhibit disagreement with molecular data, which is arguably more objective and abundant.  Here, the relationship between phenotype and genotype is explored in the context of phylogenetic reconstruction.  Morphological data matrices of extant birds were collated and characters allocated to osteological and non-osteological partitions.  Of these two regions, osteological data were found to be significantly more congruent with molecular trees as measured using ensemble retention indices (paired t-test: p < 0.001 for 19 datasets).  This trend indicates that morphological partitions may be subject to differing evolutionary pressures and that some aspects of morphology may be more informative with respect to evolutionary history than others.

The brachiopod fauna of the Fezouata Shale (Lower Ordovician) of Morocco: preliminary results

Yves Candela¹ and David A. T. Harper²

¹National Museums Scotland, UK
²Durham University, UK

The Fezouata Biota, located 20 km north of Zagora, in the Anti-Atlas of Morocco, was discovered some 17 years ago.  Within a few years of collecting it has already yielded an incredibly diverse and exceptionally preserved fauna of shelly fossils and soft-bodied specimens.  Little attention has been devoted to the brachiopod fauna, by contrast to Cambrian-like taxa or those exhibiting soft-tissue preservation.  An initial study suggests that the brachiopod fauna as a whole is more diverse than previous work has indicated.  Eleven species, so far, are recorded from the lower part of the Fezouata Shale (Tremadocian), at horizons ranging from the middle murrayi to the lower copiosus biozones.  Three species, two of which are common to the lower part, are recorded from the lower protobalticus Biozone (late Tremadocian?).  Seven species are recorded from the upper part of the Fezouata Shale (Floian), from horizons ranging from the lower jacksoni to the minutus biozones.  Overall the fauna is dominated by orthide and lingulide taxa.  In addition, a number of species in the lower part of the Fezouata Shale (copiosus Biozone) represent the oldest occurrences of their respective genera.  The composition of the brachiopod fauna reflects a typical western peri-Gondwanan affinity.

Ordovician conodonts from Peru: new data and reappraisal

Josefina Carlorosi¹, Graciela N. Sarmiento², Juan Carlos Gutierrez-Marco^2,3, Cesar A. Chacaltana⁴ and Victor Carlotto⁵

¹Institute of Geological Correlation INSUGEO-CONICET, Argentina
²Complutense University of Madrid, Spain
³Instituto de Geociencias (CSIC UCM), Spain
⁴INGEMMET, Peru
⁵Universidad Nacional San Antonio abad del Cusco, Peru

Ordovician conodont faunas are poorly known from the northern part of the Central Andean Basin, in contrast with data from the northwest of Argentina and south of Bolivia, areas located in the southern part of the same basin.  A single occurrence of late Floian conodonts of the upper Oepikodus evae Zone was reported in 2008 from the Carcel Puncco section (Inambari River valley) of southwestern Peru, close to the Subandean Fault.  Further research in the Eastern Cordillera of Peru led to the discovery of three additional occurrences of Early to Middle Ordovician conodonts, also in the San José Formation but representative of different horizons.  The first of them consists of an assemblage belonging to the Trapezognathus diprion–Baltoniodus cf. triangularis zones (late Floian), and was characterised in the Kimbiri section (Apurímac River valley).  The remaining Abra de Yanacocha and Huancampa localities provided much younger assemblages, representative of the Lenodus variabilis–Yangtzeplacognathus crassus zones (early–middle Darriwilian).  Early Ordovician conodonts from Peru display palaeobiogeographic affinities with similar assemblages known from Baltica, South China and northwestern Argentina, whereas the Middle Ordovician occurrences bear resemblances with coeval assemblages from Baltica, central South China and the Argentinean Precordillera.

Completeness of the non-avian theropod fossil record

*Daniel Cashmore, Richard J. Butler and Roger A. Close

University of Birmingham, UK

Changes in the quality of the fossil record through time and space can bias our interpretations of diversity, palaeoecology, biogeographical patterns and macroevolutionary processes.  The completeness of fossil specimens has been previously quantified for several groups of tetrapods using the character completeness metric (CCM) and the skeletal completeness metric (SCM), and used to assess fossil record biases.  CCM quantifies the phylogenetic information contained within a specimen (i.e. the proportion of phylogenetic characters it can be scored for), and SCM quantifies the proportion of a complete skeleton that a specimen preserves.  Specimen-level SCM scores were collected from the literature for over 300 non-avian theropod species that have been included in previous phylogenetic analyses.  A time series of the average completeness per geological stage was compared statistically to non-avian theropod diversity, sampling proxies (e.g. dinosaur-bearing formations) and sea level through time.  Preliminary results show that non-avian theropod completeness is at its lowest during the latest Triassic, has two peaks in the Early and Late Jurassic, and declines throughout the Cretaceous.  Theropod completeness was not significantly correlated with diversity, sampling or sea level change, but does show similarities to completeness estimates for another major dinosaur group, sauropodomorphs.

Fossil Crustacea from the Cretaceous Konservat-Lagerstätten of Lebanon

Sylvain Charbonnier¹, Denis Audo², Alessandro Garassino³ and Matúš Matúš⁴

¹CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
²Université de Rennes, France
³Museo di Storia Naturale di Milano, Italy
⁴Comenius University, Slovakia

We present a revision of the fossil crustaceans (Crustacea: Decapoda, Isopoda, Lophogastrida, Stomatopoda, Cirripedia) from the Late Cretaceous Konservat-Lagerstätten in Lebanon, Middle East.  Although knowledge about these groups has increased during recent years, fossil crustaceans from Lebanon remain poorly studied and their importance widely underestimated.  The main purpose of this study is to provide a new synthesis taking into account both the historical works and recent advances in crustacean studies.  An overall review of the fossil crustacean faunas is presented and encompasses material from Cenomanian (Hakel, Hadjoula, En Nammoura) and Santonian (Sahel Alma) outcrops.  The taxonomic treatment includes detailed descriptions of each species known to occur in the aforementioned Lagerstätten.  All the diagnoses and descriptions are presented using standard criteria and common descriptive terminology.  As much as was possible, we endeavoured to figure all the species recorded in the literature with photographs and reproductions of the historical illustrations.  Thus c. 900 specimens have been studied.  This revision also greatly improves our knowledge of fossil crustaceans by providing formal descriptions of thirteen new genera and twenty new species.  The present review is due to be published in a monograph (collection Mémoires du Muséum) by the end of 2016.

Redescription of Amiskwia sagittiformis from the Burgess Shale as a stem-group lophotrochozoan

*Brittany Cheung¹ and Jean-Bernard Caron^1,2

¹University of Toronto, Canada
²Royal Ontario Museum, Canada

Amiskwia sagittiformis, with its pair of strong cephalic tentacles, paired lateral fins, rounded caudal fin, and streamlined body, is one of the most iconic fossils from the Burgess Shale.  It has been compared to chaetognaths, nemertines, and more recently molluscs; its phylogenetic status, however, remains highly problematic.  This study is based on twenty-one new specimens from the Royal Ontario Museum and incorporates the five original Walcott specimens.  It is the first revision of Amiskwia since Conway Morris’s seminal 1977 redescription.  Specimens were studied using detailed stereomicroscopy, interference photography, SEM imagery, and elemental mapping.  The epidermis is smooth, with the exception of small spicules (c. 20 µm thick and up to 0.8 mm in length) sparsely covering the body.  The gut includes an anterior helicoidally arranged section followed by a straight and partially phosphatized intestine.  The head bears a pair of terminally attached, flexible tentacles and contains a ventrally oriented feeding apparatus with potential salivary glands – previously interpreted as cerebral ganglia and the anterior gut – with closely, regularly spaced comb-like structures.  Other internal features include potential muscular, vascular, and nervous tissues.  Amiskwia lacks defining features of any modern phylum; however, the presence of spicules suggests a connection with lophotrochozoans.

Cretaceous bearing formations effect on modelling dinosaur diversity

Alfio A. Chiarenza, Peter A. Allison and Philip D. Mannion

Imperial College London, UK

Every environment contains a specific set of conditions that act on fossil remains, representing the combined influence of local agents (e.g., landscape, precipitation, temperature).  As habitats shift in response to macro-scale change, the nature and distribution of preservation regimes also vary, creating cascading effects through the diagenetic processes associated with particular environments.  We outlined a new modelling approach to evaluate the impact of physical variables in biasing the fossil record, revealing whether potentially suitable environments for fossil vertebrate preservation made it into the lithosphere.  We focused on the latest Cretaceous (Campanian and Maastrichtian) of western North America, an area yielding considerable data on dinosaur distribution and which has been the focus of a notable volume of research.  A new high-resolution global atlas of palaeogeographic maps for regional-scale palaeogeographic interpretations has been used in conjunction with a HadCM3 coupled global climatic model run over these palaeogeographies.  Palaeontological data have been harvested from databases (Paleobiology Database) and the literature.  Habitat modelling and estimated variation in niche ranges gives a new glimpse into some main biogeographic events concerning dinosaur communities during what is considered a ‘high diversity window’ in the evolutionary history of dinosaurs and the lead-up to the K-Pg mass extinction.

Systematic review of Messinian crabs of Oran (Algeria)

Cédric Chény¹, Denis Audo¹, Jean-Paul Saint Martin² and Simona Saint Martin²

¹Université de Rennes, France
²CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France

During the Messinian, the temporary closure of the Strait of Gibraltar caused several desiccation phases in the Mediterranean basin.  The impact of this crisis on decapod crustaceans has yet to be studied.  A first step toward this goal is to further our knowledge on pre-evaporitic decapods.  Our study focuses on the diverse and well-preserved fauna of crabs from the early Messinian ‘yellow marls’ of Oran (Algeria) in the Les Planteurs and Ravin Blanc outcrops.  We based this study on 55 specimens including type specimens and unpublished material.  A micropalaeontological analysis revealed that both outcrops correspond to similar fully-marine environment.  Our systematic revision allowed us to recognize seven species ascribed to five genera, listed here in decreasing order of abundance: Lobocarcinus, Geryon, Maja, Calappa, Hyas – from the most common to the rarest.  Among those we describe two new species: Lobocarcinus nov. sp. which was previously confused with the more recent (Pleistocene) L. sismondai, and a second species of Geryon sp. only known from Ravin Blanc.  Since Lobocarcinus are abundant in the Mediterranean area from the Miocene to the Pleistocene and the other species are ascribed to genera with extant representatives, this fauna from Oran provides an interesting comparison point between environments before and after the Messinian crisis.

Carbon isotope stratigraphy, biostratigraphy and correlation of the Lower Cambrian Shackleton Limestone, Transantarctic Mountains, Antarctica

Thomas M. Claybourn¹, Lars E. Holmer¹, Glenn A. Brock², Christian B. Skovsted³, Timothy P. Topper⁴, Lars Stemmerik⁵ and Paul M. Myrow⁶

¹Uppsala University, Sweden
²Macquarie University, Australia
³Swedish Museum of Natural History, Sweden
⁴Durham University, UK
⁵University of Copenhagen, Denmark
⁶Colorado College, USA

During the early Cambrian, East Antarctica and Australia were sutured together forming East Gondwana, sharing a geological and palaeontological history.  New fossils and stable carbon isotope data from the Shackleton Limestone of East Antarctica is a piece in the puzzle of the Lower Cambrian biostratigraphy of East Gondwana that has remained poorly resolved since its discovery.  The shared presence of Dailyatia odyssei Evans and Rowell, 1990 between the Shackleton Limestone and the Arrowie Basin of South Australia demonstrates that the Shackleton Limestone correlates to the new Dailyatia odyssei biozone erected for South Australia, indicating a Cambrian Series 2 Stage 3 age for the Shackleton Limestone.  All species described are also present in Series 2 Stage 3-4 sedimentary deposits of either the Stansbury or Arrowie Basins of South Australia.  Helcionelloid molluscs and hyoliths also demonstrate a link to the Bastion Formation, North-East Greenland.  Shared taxa with the lower Cambrian glacial erratics from the South Shetland Islands shows these fossils were sourced from rocks at least coeval to the Shackleton Limestone, but not from outcrops described herein.  Correlations to the Xinji Formation of North China are also discussed.  Difficulties arise in interpreting isotopic data, as clear excursions do not always exist with fossil data and vice versa.  Nevertheless, correlations to secular isotope excursions are hypothesized and highlight the requirement for multiple lines of stratigraphic data for stratigraphic correlation.

Investigating the molluscan fauna of the Shackleton Limestone (Transantarctic Mountains, Antarctica) with linear and outline morphometrics

Thomas M. Claybourn¹, Illiam Jackson¹, Lars E. Holmer¹, Glenn A. Brock², Christian B. Skovsted³ and Timothy P. Topper⁴

¹Uppsala University, Sweden
²Macquarie University, Australia
³Swedish Museum of Natural History, Sweden
⁴Durham University, UK

The molluscan fauna of the lower Cambrian (Series 2 Stage 3-4) Shackleton Limestone contains an abundance of helcionelloid steinkerns.  The fauna of the Shackleton Limestone allows identification of a strong biogeographic link between East Antarctica and South Australia, and the Bastion Formation of North-East Greenland.  Amongst the helcionelloids, bilaterally compressed, incomplete internal moulds likely belonging to the stenothecids are common.  The loss of the basal-most part of the steinkern results in the loss of the taxonomically important parietal train, leaving only the simple apical portion.  The lack of informative morphology of this molluscan fauna mounts a challenge for phylogenetic analysis and landmark-based morphometrics due to a lack of characters and homologous points.  We employ a morphometric approach to understanding the relationships of these fossils, which quantifies the morphology and compares them to similar material from coeval sedimentary deposits in order to identify overall patterns of similarity and identify putative phylogenetic relationships.  This is achieved by studying the angle created between the comarginal ribs of the specimens as well as by conducting an elliptical Fourier analysis (EFA).  This work is relevant to theoretical discussion on species delimitation in the fossil record and the nature of the species concept in its palaeontological application.

Global diversity patterns of Lepidosauria from the Triassic–Oligocene: what can they tell us about the long-term evolutionary history of the clade?

*Terri J. Cleary^1,2

¹Natural History Museum, London, UK
²University College London, UK

Lepidosauria (which includes lizards, snakes and the tuatara) is a successful extant clade that originated at least 240 million years ago, and is represented by a wide variety of fossil forms.  Long-term patterns of diversity have yet to be comprehensively assessed, particularly for terrestrial taxa.  Here I examine terrestrial lepidosaur diversity, from the Triassic to Palaeogene (252-23 Ma), on genus-level occurrences (1,973 specimens representing 458 genera) from the Paleobiology Database.  Shareholder quorum subsampling (SQS) was used to produce a sampling-corrected taxic richness curve.  At a quorum >0.5, there is a decline in diversity across the Triassic/Jurassic and Jurassic/Cretaceous boundaries.  A major peak in diversity occurs in the Campanian, dipping sharply before the K-Pg mass extinction.  A subsequent Paleocene rise likely represents recovery following this.  Diversity peaks again in the early Eocene, followed by a decline in the late Eocene, and another recovery into the Oligocene; this may be associated with the Grande Coupure event.  Data are highly skewed, with 45% of specimens originating from North America, a clear indication of sampling bias.  It is important therefore to examine diversity at smaller scales, e.g. continent-level or lower, in order to better understand the possible differential effects of extinction events on multiple continents.

A history of sea serpents: reassessing the early fossil record of Lampridiformes (Teleostei: Acanthomorpha)

*Donald Davesne¹ and Matt Friedman^1,2

¹University of Oxford, UK
²University of Michigan, USA

Lampridiformes is a morphologically distinctive clade of marine pelagic spiny-rayed fishes, including iconic species such as the homeothermic opah (Lampris guttatus) and the giant elongated oarfish (Regalecus glesne).  A relatively high number of lampridiform relatives are known in the fossil record, as early as the Late Cretaceous (~95 Ma).  However, the phylogenetic position of most of these fossil taxa is poorly constrained.  In order to better understand their early evolution, we reviewed several Palaeogene fossil taxa.  For example, Whitephippus (Eocene of England) is redescribed with CT-scan data.  In contrast with previous interpretations, we show that this taxon is one of the oldest anatomically modern Lampridiformes.  On the other hand, the very strange Bajaichthys from the Eocene of Italy, while described as an elongated lampridiform (Taeniosomi), belongs in fact to Zeiformes (dories).  Finally, we present a preliminary phylogenetic analysis of Lampridiformes including Palaeogene taxa alongside modern diversity.  A collection of deep-bodied, so-called ‘veliferoid’ fossil taxa are placed at varying positions in the tree, helping to break down the sequence of acquisition of modern lampridiform’s characters states.  The oldest crown-Lampridiformes are found in the earliest Paleocene, suggesting that the diversification of the group took place rapidly after the K-Pg extinction event.

Architecture of the Laureacean inflorescence Mauldinia revisited

Véronique Daviero-Gomez¹, Bernard Gomez¹, Clément Coiffard² and Vincent Girard³

¹CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
²Museum für Naturkunde, Germany
³Institut des Sciences de l’Evolution de Montpellier, France

Abundant inflorescence fragments of Mauldinia have been collected from the Cenomanian of Saint-Laurent-la-Vernède and Saint-André-d’Olérargues, southeast France.  The slender axis bears tiny, caduceus, spirally arranged, lateral units, each borne at the axilla of one persistent subtending bract.  Lateral units have a bilateral symmetry, a marked dorsi-ventral flattening, a slight concavity, and a ventral position of flowers.  Besides their small sizes, they can bear up to nine sessile flowers and fruits, which leave circular scars.  Each lateral unit is a contracted inflorescence with sutures of pieces that are difficult to distinguish.  The rough bilobed shape was previously interpreted as fused bracts, cladodes or bracteoles.  According to our research, it derives from the compression of a determinate inflorescence of double cyme with acropetal maturation.  The dorsal surface of the lateral unit shows tiny folds that we interpret as bracts.  This cymose organization of lateral unit occurs in living Lauraceae; however, such a compressed unit with this shape is unknown in any living families.  The whole inflorescence corresponds to a ‘dichasium spike’.  It resembles catkins due to its small size, which suggests that they may have been pendant as in birch.  This original architectural model illustrates the already diversified inflorescences of early angiosperms from the Cenomanian.

Systematic reassessment of the earliest mammalian fauna (Saint-Nicolas-de-Port, Upper Triassic, France)

Maxime Debuysschere

CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France

The locality of Saint-Nicolas-de-Port (Upper Triassic, France) yielded the most important collection of earliest mammaliaforms.  This collection includes more than three quarters of the available material for Triassic mammaliaforms, with representatives of all groups (morganucodonts, ‘symmetrodonts’, and haramiyids).  However, despite twelve publications between 1978 and 1999, most of this material remains undescribed.  After description of around 500 molariform and premolariform teeth, 18 species and three indeterminate taxa are identified.  Among morganucodonts, several genera known in other sites are recognized (Morganucodon, Paceyodon, Paikasigudodon).  Two new species are described (Megazostrodon chenali sp. nov. et Rosierodon anceps gen. et sp. nov.).  Upper and lower molariforms of Brachyzostrodon are associated for the first time.  Among ‘symmetrodonts’, one new species of Kuehneotherium, K. stanislavi sp. nov., and a new genus of Kuehneotheriidae, Fluctuodon necmergor gen. et sp. nov., are described.  Woutersia is revised.  The hitherto unknown upper molariforms of Delsatia are identified.  Among haramiyids, the description of the material referred to Thomasia demonstrates the need for an exhaustive revision of this genus.  Theroteinus is revised, with the erection of a new species, T. rosieriensis sp. nov.  This study raised several issues on the systematics of earliest mammaliaforms, especially on definition of key taxa.

Erymid fauna (Crustacea: Decapoda: Erymidae) in french Early Cretaceous deposits

Julien Devillez, Sylvain Charbonnier and Lucien Leroy

CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France

Erymid lobsters (Crustacea, Decapoda, Erymidae) are relatively common and abundant in Jurassic rocks (c. 70 species) but are far less common in the Early Cretaceous with only around 20 species listed in Europe, North America, South America, Australia, Antarctic, Japan and Madagascar.  Here we present a study of the twelve species of erymid lobsters from the Early Cretaceous of France.  Based on new observations, the concepts of some erymid genera are updated and new diagnoses are proposed for Eryma Meyer, 1840, Enoploclytia M’Coy, 1849, Palaeastacus Bell, 1850, Pustulina Quenstedt, 1857 and Stenodactylina Beurlen, 1928, including carapace groove pattern, morphology of first pereiopods and also a complex new structure – the post-orbital area – located in front of the cephalic region.  The new genus Tethysastacus is erected on the basis of its very simple groove pattern compared to previous genera and includes Tethysastacus tithonius (Van Straelen, 1936) n. comb. (Valanginian, France) as type species.  Four new species from France are also described: Eryma vocontii n. sp. (Albian) which extends the stratigraphic range of Eryma to the Albian, Pustulina occitana n. sp. (Berriasian), Pustulina colossea n. sp. (Hauterivian) and Enoploclytia augustobonae n. sp. (Barremian) which is the oldest known Enoploclytia representative.

The ecological and phylogenetic significance of gill arch and gill raker morphology from computed tomography (CT) scanning

*Claire Dobson¹, Zerina Johanson², Sam Giles¹ and Matt Friedman^1,3

¹University of Oxford, UK
²Natural History Museum, London, UK
³University of Michigan, USA

Pachycormids are a modestly diverse clade of Mesozoic fishes thought to show a range of trophic ecologies.  Claims about pachycormid feeding ecology have largely been made based on external anatomy (e.g. jaw and tooth structure), but there is some evidence for additional specializations of the gill arches and associated rakers.  In order to further investigate the relevance of these undersampled traits, we used CT scanning to examine in situ gill skeletons of pachycormids with very different oral dentitions: the tooth-bearing Pachycormus (Early Jurassic), the fang-bearing Hypsocormus, and edentulous Martillichthys (both Late Jurassic).  We find that raker morphology differs considerably between these genera.  Based on revised phylogenetic analyses incorporating our new anatomical observations, we find that taxa with broadly similar raker morphologies are closely related, with the most conspicuous example being the presence of long, elaborate rakers in the putatively suspension-feeding edentulous pachycormids.  This suggests that raker morphology provides both phylogenetic and ecological information, and that key divergences in pachycormid evolution that appear to be ecologically driven are associated with apomorphic gill raker morphologies.  Inclusion of additional characters observed via CT may further improve understanding of pachycormids relationships to both one another and other early crown neopterygians.

Intrinsic and extrinsic ecological determinants of extinction at the End-Triassic mass extinction

Alexander M. Dunhill¹, William J. Foster², James Sciberras³ and Richard J. Twitchett⁴

¹University of Leeds, UK
²University of Texas at Austin, USA
³University of Bath, UK
⁴Natural History Museum, London, UK

We assess the ecological effect of the End-Triassic mass extinction on marine communities along with the functional patterns of recovery into the Early Jurassic.  Using the Bambach ecospace model, we show that, although taxonomic extinction was severe, extinction amongst functional groups was less so, with only two modes of life apparently disappearing at the end of the Triassic.  We assess how intrinsic and extrinsic ecological factors influence extinction intensity.  Extinction was highest in the tropics, and Panthalassan taxa suffered higher extinction rates than taxa residing in the Tethys Ocean.  Reef taxa suffered the highest levels of extinction, whilst those inhabiting the continental shelf were the least affected.  An erect benthic or pelagic mode of life appears to have been most susceptible to extinction whilst suspension feeders, particularly those with presumed symbiotic relationships, suffered higher extinction rates than taxa displaying other feeding strategies.  Non-motile taxa appear to have suffered higher levels of extinction than motile taxa.  The results show that both intrinsic and extrinsic ecological factors have a bearing on whether taxa are more or less likely to survive a mass extinction event and that determinants of extinction at major biotic crises differ from those during periods of background extinction.

Testing terrestrial tetrapod diversity change across the Carboniferous–Permian Boundary

*Emma Dunne¹, Roger A. Close¹, Roger B. J. Benson² and Richard J. Butler¹

¹University of Birmingham, UK
²University of Oxford, UK

The Carboniferous and Permian (359–252 Ma) witnessed the establishment of the first terrestrial tetrapod ecosystems against a backdrop of major environmental change, including the collapse of the tropical rainforest biome at the end of the Carboniferous.  However, there is disagreement surrounding the patterns of tetrapod diversity change during this interval, stemming from the ongoing debate on the importance of spatial and temporal sampling biases in the fossil record.  To investigate early tetrapod diversity across the Carboniferous–Permian boundary, a new global dataset (>400 species from 520 unique localities) has been created within the framework of the Paleobiology Database.  Raw data suggest a major increase in global and alpha taxic diversity from the late Carboniferous to early Permian, punctuated by lower diversity in the earliest Permian (Asselian–Sakmarian).  This is distinct from previous datasets, which showed continuous diversity increases through this interval.  However, these estimates do not account for temporal variations in sampling.  We estimated sampling using formation counts and locality numbers, and used a residuals approach to model diversity changes: provisional results support a period of reduced diversity in the earliest Permian, following the rainforest collapse.  Ongoing work is estimating diversity using additional approaches including SQS and TRiPs.

Geochemistry of early Middle Triassic sedimentary sequences from Winterswijk (the Netherlands): reconstructing the palaeoenvironmental conditions and taphonomic preservation of a sauropterygian assemblage

*Melanie A. D. During¹, Anne S. Schulp^1,2, Dennis F. A. E. Voeten³, Jarmo Pietersen¹, John J. G. Reijmer¹ and H. Jeroen L. van der Lubbe¹

¹Vrije Universiteit Amsterdam, Netherlands
²Naturalis Biodiversity Center, Netherlands
³Palacký University, Olomouc, Czech Republic

The Winterswijkse Steengroeve quarry complex in the east of the Netherlands exposes a ~40 m thick sedimentary sequence comprising intertidal and shallow marine strata.  The overall transgressive sequence consists of primary and reworked carbonates of a microbial origin.  These early to middle Anisian strata were deposited in and alongside the northeastern margin of the epicontinental Muschelkalk Sea.  Numerous beds within the succession preserve a shallow marine palaeofauna through a relative abundance of skeletal material from sauropterygians, fishes and crustaceans.  Improved insight into the trophic relations within this habitat can help elucidate the mode and pacing of ecological recovery after the Permo–Triassic mass extinction event.  Biogeochemical proxies may provide crucial information on such ecological interrelations, but untangling the primary biological signal from secondary diagenesis has proven to be complex.  Here we present a detailed lithostratigraphical description accompanied by natural gamma-ray analysis and stable carbon and oxygen isotope data of the sediment matrix from the Winterswijkse Steengroeve locality.  These stratigraphic records and geochemical analyses provide important information regarding the sedimentary and diagenetic conditions and will aid correlation.  This contextual information on preservation and palaeoenvironment is a prerequisite towards understanding the trophic relations during the biotic recovery after the Permo–Triassic mass extinction.

Myriapod transcriptomics and the timing of terrestrialization

Gregory D. Edgecombe¹, Rosa Fernandez² and Gonzalo Giribet²

¹Natural History Museum, London, UK
²Harvard University, USA

Phylogenomic analyses of Myriapoda based on novel Illumina transcriptomes have reinforced myriapod monophyly and a sister group relationship with Pancrustacea, strengthened a centipede-millipede clade as an alternative to the traditional Progoneata, and retrieved ordinal-level topologies that are mostly compatible with morphological hypotheses.  For the most complete taxonomic sample (including most orders of Diplopoda and nearly all families of Chilopoda), ten supermatrices explored the effect of several potential phylogenetic biases at different levels of gene occupancy per taxon.  The morphologically-supported scheme of centipede relationships is recovered in matrices that maximize gene number but at the expense of lesser gene occupancy, whereas more complete matrices using fewer genes produce more morphologically anomalous groupings.  Coding calibration fossils in a morphological matrix designed around extant species in the transcriptomic sample facilitates internally-consistent node calibration as well as total evidence dating.  The first Illumina transcriptomes for Pauropoda and both symphylan families allows the Edafopoda versus Dignatha controversy to be tested.  Divergence estimates for total-group Chilopoda and Diplopoda in the Cambrian substantially pre-date palaeontological evidence for these groups, which are first known from crown-group fossils in the Pfont-family:ArialNarrow'>řidolí-Lochkovian.  The myriapod stem group remains one of the enigmas of the arthropod fossil record.

The Pleistocene rise and current threat of the reef coral Acropora

Kilian Eichenseer and Wolfgang Kiessling

Friedrich-Alexander University of Erlangen-Nuremberg, Germany

Staghorn corals of the genus Acropora are dominant reef-builders in modern Indo-Pacific reefs and have been prevailing in Caribbean reefs until the 20th century.  The fossil record of Acropora dates back to the Paleocene, yet throughout most of the Cenozoic, Acropora is a minor component of fossil reefs and only became widely abundant during the Pleistocene.  To demonstrate the veracity of this trend we investigated spatial and temporal fluctuations of Acropora abundance and diversity in the Cenozoic fossil record and today.  Neither climatic data predicting weathering intensity nor experiments on the dissolvability of different coral genera indicate a taphonomical bias against Acropora in the fossil record.  To explain the apparent mismatch between the evolutionary rise of Acropora and its ascent to ecological dominance in reefs, glacioeustatic sea-level fluctuations have been evoked.  The fast growth and easy asexual reproduction by breaking off branches allowed staghorn corals to keep up with rapid sea-level rise.  In contrast to its geologically recent success, Acropora is particularly vulnerable to anthropogenic stressors.  Fossil abundance of coral genera appears to be unrelated to their ability to cope with the recent disturbances.

Body size evolution in major amniote clades during the late Palaeozoic–Early Mesozoic

*Armin Elsler¹, Michael J. Benton¹, Marcello Ruta², Alexander M. Dunhill³

¹University of Bristol, UK
²University of Lincoln, UK
³University of Leeds, UK

Basal therapsids, archosauromorphs and parareptiles were characteristic elements of terrestrial faunas during the Palaeozoic to Mesozoic transition.  Late Permian and Early Triassic ecosystems were dominated by Therapsida.  These ecosystems were subsequently replaced by archosauromorph-dominated ecosystems in the later part of the Triassic.  The parareptiles flourished mainly during the middle Permian, hit a diversity peak right after the end-Permian mass extinction event but went extinct at the end of the Triassic.  Here we present preliminary results of our analyses of body size evolution during the Late Permian–Early Jurassic in these major amniote clades.  Using phylogenetic comparative methods different models of continuous character evolution were fitted against available body size data.  The changes in body size among archosauromorphs are best explained by an early burst (EB) model.  Parareptiles follow an Ornstein–Uhlenbeck (OU) model.  Models that allowed for rate variation along different branches did not outperform a simple Brownian motion (BM) model in both cases.  Body size evolution in Therapsida is best explained by an OU model (closely followed by EB).  A heterogeneous rate model was favoured over a homogeneous rate BM model.  Major rate increases are found among Late Permian dicynodonts and Early-Middle Triassic therocephalians.

Assessing the burrowing capacity in trilobites using finite element analysis

Jorge Esteve¹ and Jordi Marce-Nogue²

¹Complutense University of Madrid, Spain
²University of Hamburg, Germany

An infaunal ethology has been confirmed for some trilobites such as the Cambrian Agraulos or the Ordovician Asaphus due to in situ preservation.  However, burrowing behaviour is inferred (most of the time) for the functional morphology of trilobite taxa and a total lack of direct evidence is found.  This is the case for some Cambrian and Ordovician trilobites such as Monkaspis, Neseuretus or Megistaspis.  Monkaspis and Megistaspis had some morphological features such as a dagger-shaped body, smooth surface, wedge-shaped cephalon and the blade-shaped space in front of the glabella that seemingly allowed them an infaunal burrowing behaviour.  However, in the case of Neseuretus, Asaphus and Agraulus they do not have such a mosaic of morphological features.  Given this disagreement between the shape and the putative behaviour, we assess their capacity, from a biomechanical point of view, to make burrows using final element analysis (FEA).  The stress distributions and the displacements obtained from the FEA models show a correlation between the areas with lower stresses and lower displacements in the librigenae.  These results point out a structural behaviour in the cranidia capable of withstanding the forces produced during burrowing.

Secular variation of Bathynotus kueichouensis (Cambrian Series 2 Stage 4) from the Wuliu-Zengjiayan section of the Kaili Formation, South China

Jorge Esteve¹, Yuanlong Zhao² and Jin Peng²

¹Complutense University of Madrid, Spain
²Guizhou University, China

Geographic variation is important in taxonomy, but temporal variation enjoys less attention, mainly because of the lack of sample size.  Taxa close to extinctions suffer environmental stresses due to abiotic factors such as fewer food resources and isostatic or chemical changes.  A secular study of the morphology below an extinction level allowed us to recognize morphological patterns prior to the extinction event.  The cosmopolitan Bathynotus kueichouensis disappears a few metres below the Cambrian Series 2-3 border.  Here we present a preliminary study to assess the morphological variation using geometric morphometric methods throughout the stratigraphic record of this taxon from a single section.  The preliminary results suggest a variation in the size of the palpebral lobe, being larger in the early specimens and becoming increasingly smaller towards the top of the section.  A possible interpretation of this is environmental changes from deeper water to shallower waters toward the top of the stratigraphic record of B. kueichouensis.  Further work is necessary and more taxa need to be included in this study to assess whether morphological patterns can be recognized prior to an extinction.  Thus, causes of the secular variation of B. kueichouensis remain open.

High ectoparasitic pressure in early vertebrates inferred from the analysis of their squamation patterns

Humberto G. Ferron¹, Carlos Martinez Perez^1,2, Jose Franciso Palacios-Abella¹ and Hector Botella¹

¹University of Valencia, Spain
²University of Bristol, UK

Parasitic evidence is difficult to ascertain in the fossil record due to the soft-bodied nature of parasites.  Only a few cases of exceptionally preserved fossils show traces or skeletal pathologies that can be putatively linked to a parasitic origin.  Interestingly, several authors have proposed that some aspects of the squamation of schooling sharks have evolved in response to ectoparasitic pressure, providing an alternative approach for addressing this issue.  Here we characterise the squamation pattern of extant schooling sharks, measuring different scale variables in eight body areas of 70 specimens, in order to establish a comparative framework for predicting high ectoparasitic pressures in extinct vertebrates.  Our results show that species under strong ecotoparasitic pressure have optimized some aspects of their squamations (reduction in the scale density and increase in crown angle) avoiding the settlement of ectoparasites.  Similar patterns are here described in the thelodont Lanarkia horrida, suggesting that ecotoparasitism could be an important pressure selection in the early stages of the evolution of the group, and that social interactions could be present in vertebrates as early as Silurian times.

Evolution and functional morphology of Cretaceous pelagic microcrinoids

Andrew S. Gale

University of Portsmouth, UK

The Roveacrinida are tiny pelagic microcrinoids which were abundant, even locally rock-forming, in Cretaceous oceans, but are often missed or ignored by palaeontologists.  They underwent two main periods of phylogenetic radiation (Albian, Lower Campanian) both of which generated diverse and unusual morphologies which are interpreted as adaptations for weight reduction (skeletal thinning and voids), protection (short arms which cover soft tissues and elongated spines) and vertical migration in the upper water column (stabilizing spines, asymmetrical processes to cause rotation).  The record of the latter radiation (Campanian) is very well represented by diverse taxa, and phylogenetic analysis demonstrates the presence of iterative morphological trends.  Roveacrinida remained abundant and moderately diverse up to the K-Pg boundary event, which evidently brought about their extinction.

Evaluation of several cladistic methodologies and their impact on a palaeontological dataset: the case of Diplodocidae (Dinosauria: Sauropoda)

Simone Giovanardi¹, Emanuel Tschopp¹ and Paul Upchurch²

¹Università degli studi di Torino, Italy
²University College London, UK

In order to assess reliable phylogenetic relationships between different taxa using cladistics, a good dataset by itself is not sufficient.  The methodology with which the matrix of characters is treated plays a key role in the recovery of evolutionary lineages.  The aim of this study is to discover the best methodologies to analyse the matrix of a particular clade: the Diplodocidae.  Twelve analyses were performed, confronting different types of characters (discrete or continuous), weighting procedures (a priori weighting versus implied weighting) and ways to implement uncertain ratios or ranges in continuous characters.  The results obtained were evaluated with the aid of different stratigraphic indexes to determine which methodology performed better by placing the most ancient taxa in a more basal position in the phylogenetic tree compared to more recent ones.  In conclusion, the methodologies that perform better are the ones based on discrete characters scores, whereas the adoption of implied weighting does not seem to have a great influence.  The use of uncertain character measures can lead to unresolved phylogenetic trees, which is probably due to the implementation of the algorithms used in the phylogenetic analysis.

³⁴S/³²S of vertebrate apatite: a new tracer of past living environment

Jean Goedert¹, Romain Amiot¹, François Fourel¹, Laurent Simon² and Christophe Lécuyer¹

¹CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
²CNRS UMR 5023, Université de Lyon, France

In ecological studies, the sulfur isotope composition (δ³⁴S values) of soft tissues allows the determination of both past and present-day living environments of organisms.  However, technical limitations have so far prevented reliable sulfur isotope analyses of minerals having low sulfur content, such as bioapatite, the crystalline component of skeletal tissues.  The development of ‘purge-and-trap’ technology in elemental analysers has recently demonstrated new possibilities to solve some of those technical difficulties.  We have used a VarioPYROcube elemental analyser (EA) equipped with ‘purge-and-trap’ technology, interfaced in continuous flow mode to an Isoprime 100 isotope ratio mass spectrometer, to measure the sulfur isotope compositions of bioapatite samples.  Our results demonstrate the capacity of this analytical setup to measure the δ³⁴S_V-CDT values of low-S bioapatite samples (0.14 to 1.19 wt%) with a good analytical precision (1s = 0.5; n = 14).  Our results also show that the δ³⁴S_V-CDT values of modern and fossil vertebrate bioapatites allow discrimination between marine environments and freshwater or terrestrial ones.  Sulfur isotope analysis of bioapatite has great potential to track the living environment of extinct vertebrates for which only fossilized bones or teeth have been preserved.

Oceanic island vegetation buried by recurrent Holocene explosive eruptions: preliminary results from Faial Island (Azores, Portugal)

*Carlos A. Góis-Marques^1,2, Lea de Nascimento³, Miguel Menezes de Sequeira²,
José María Fernández-Palacios³ and José Madeira¹

¹Universidade de Lisboa, Portugal
²Universidade da Madeira, Portugal
³Universidad de La Laguna, Canary Islands, Spain

On volcanic islands, the interaction between explosive volcanic events and the vegetation creates ideal taphonomical settings for plants and soils to be buried and preserved.  In the Azores Islands the palaeobotanical record is linked with the volcanic activity.  Although plant macrofossils have been known since the 19th century, palaeovegetation diversity and palaeoecology of Azores Islands is still poorly known.  Efforts to define a pre-colonization vegetation are based mainly on historical descriptions, on the surviving native vegetation, and on fossil pollen analysis from lake or bog cores.  Here we present the preliminary results from a palaeobotanical survey on Faial Island.  The island has a record of 12 sub-plinian and phreatomagmatic trachyte eruptions younger than 16 ka BP.  Several sites with unaltered trunks, charcoalified trunks in ignimbrite deposits and leaf fossils preserved in tuffs, associated with palaeosols, were recognized during fieldwork.  Other outcrops expose palaeosols preserved within sequences of pumice fall deposits.  We propose that the combination of macrofossils and pollen assemblages from palaeosols buried by deposits of the same volcanic event sampled at different elevations will contribute to the reconstruction of Faial Island’s past vegetation.  Moreover, the vegetation resilience between eruptions can be tested.  Extant neoecological studies of Azores vegetation will gain significantly from this palaeobotanical perspective.

The fossil record of the other end of the size range – tiny predatory arthropods

Carolin Haug¹, Marie K. Hörnig² and Joachim T. Haug¹

¹LMU Munich, Germany
²Erst-Moritz-Arndt-Universität Greifswald, Germany

A predator is a fascinating type of organism.  Part of this fascination is perhaps caused by the feeling of being in danger when thinking of or looking at a predator.  This is likely also the reason why a majority of the public like large or super-sized predators.  Luckily, the fossil record has a rich variety of such forms available.  Groups such as eurypterids, Anomalocaris, Dunkleosteus, Liopleurodon or Tyrannosaurus can be easily recognized by the non-specialist.  Yet, these super-sized predators are nothing less than the tip of the iceberg.  Many more medium-sized predators have been identified in the fossil record, each being a few centimetres in size and eating smaller prey whilst most likely being themselves eaten by the larger predators.  We can even scale further down.  Many modern-day predators are less than 5 mm in size and represent an important part of the modern food web.  It might seem more unlikely that such small-sized predators can be identified in the fossil record.  However, we will present examples of such tiny fossil predators from among the arthropods, from various eras throughout the Phanerozoic and in numerous different preservation types.

Journal of Paleontological Techniques: a free, open-access journal exchanging knowledge between technicians, preparators and researchers

*Femke Holwerda^1,2,4 and Emanuel Tschopp^2,3,4

¹Staatliche Naturwissenschaftliche Sammlungen Bayerns, Germany
²Universidade Nova de Lisboa, Portugal
³Università degli Studi di Torino, Italy
⁴Museu da Lourinhã, Portugal

The Journal of Paleontological Techniques (JPT) was established in 2006 in the Museu da Lourinhã (ML), Portugal, to provide a platform for preparators of the ML to share ideas and knowledge with their peers.  It has grown to be an open-access, free journal, publishing mostly on the collection, preparation, conservation and exhibition of natural history objects, such as holotypes of extant species, fossils and historical museum specimens.  These natural history objects provide a wealth of information on past and present biodiversity.  Because collection and/or conservation techniques might alter the objects in ways that could negatively influence the outcomes of future research, a detailed report of the methodologies used from acquisition to conservation of specimens is crucial.  Despite the importance of such reports, until recently, no specific, scientific publications existed for museum technicians and scientists to share knowledge.  The Journal of Paleontological Techniques publishes a wide variety of articles, ranging from excavation reports and papers on preparation techniques to new methodologies in collection management and scientific study, among others.  Manuscripts are subjected to peer-review to ensure high scientific standards.  Papers are published as single-paper volumes upon final approval of the proofs, and are available in PDF format under a CC-BY licence.  The editorial board currently consists of an international group of early-stage scientists.  Most editors have a palaeontological background; however, all have a unique expertise within that field (e.g. microscopy, photogrammetry, phylogeny, morphometrics, preparation and microbiology).  JPT welcomes your submissions!

Skeletal structure and function in the stemless crinoids Marsupites and Uintacrinus

Jennifer F. Hoyal Cuthill^1,2 and Aaron W. Hunter^2,3

¹Tokyo Institute of Technology, Japan
²University of Cambridge, UK
³Curtin University, Australia

Marsupites and Uintacrinus were unusual articulate crinoids with an enlarged, globose calyx and five long, branched arms, but no stem, holdfast or other attachment structures.  They lived during the Late Cretaceous ‘golden age’ of crinoid diversity, reaching near-global distribution with up to five species and subspecies stretching across the Boreal, Tethyan and Austral realms.  They are also known for their exceptional preservation in Lagerstätten such as the Niobrara Chalk, Kansas, USA.  The stratigraphic ranges of the two genera overlap, relatively briefly, for 200 ka in the Santonian–Campanian.  They remain somewhat enigmatic, with alternative life habits suggested: from a benthic reclining ‘snowshoe’ to an actively swimming ‘hemipelagic dredger’.  It appears, however, that they may have shared a unique calyx structure.  Here we present analyses of skeletal structure, including plate size, density and organization, with implications for the life habits and evolutionary relationships of these aberrant Cretaceous taxa.

Exploring the unrealised potential of the brachiopod collections at the Natural History Museum, London

Zoe Hughes, Chris Hughes, Richard J. Twitchett and Kenneth G. Johnson

Natural History Museum, London, UK

The NHM, London’s brachiopod collections have enormous, unrealised, scientific potential.  Well-preserved brachiopods are an archive of palaeoenvironmental information, and geochemical analyses of their shells provide proxy data for a range of parameters such as temperature.  They are common, robust, and widespread, and are model organisms for size-change studies.  There are ~1,000 drawers of Mesozoic and Cenozoic brachiopods in our collections, which provide a potential of several orders of magnitude increase in published occurrences from that critical time interval.  One key problem in realising this potential is the current curatorial state of the collections.  The absolute numbers of specimens are unknown (as many individuals might be registered under one number); others are in old, unacceptable containers, lack critical locality or stratigraphical information, or are in too poor a state to be easily digitized.  As a first step in realising the full potential of our brachiopod collections we are conducting a collections survey to enhance their potential utility and to identify those that have most scientific potential and which should be prioritized for digitization.  Preliminary results indicate that there are c. 400,000 Mesozoic–Cenozoic specimens of which 20% are assigned to the best stratigraphic and geographic resolution.

Reconstruction of the motion and hindfoot posture of Rhoetosaurus brownei Longman, 1926 (Sauropoda, Gravisauria)

Andréas Jannel, Olga Panagiotopoulou, Anthony Romilio, Jay P. Nair and Steven W. Salisbury

University of Queensland, Australia

The Middle Jurassic (Late Bathonian–Middle Callovian) basal sauropod Rhoetosaurus brownei is the largest known pre-Cretaceous terrestrial Australian vertebrate.  Represented as a near-complete right hind limb, key aspects of the palaeobiology of Rhoetosaurus remain unresolved.  The current study combines three-dimensional modelling and photogrammetry to reconstruct the range of motion (ROM) of the foot of Rhoetosaurus to elicit pedal flexibility and posture.  Our findings show that Rhoetosaurus had a high degree of digit mobility at all the metatarsophalangeal joints (total excursion angle >80°) and in the sagittal, transverse and frontal planes at the distal-most interphalangeal joints (excursion angle >100°).  The position of the autopodial articular surfaces suggests that the metarsophalangeal joints were permanently elevated in life, an indicator of skeletal digitigrady.  This joint may have been ventrally connected with the plantar aspect of the foot by a compliant fibrous pad, consistent with sauropod track data, and therefore likely to have been functional plantigrade, as has been previously suggested.  These results provide new insights into the simulated ROM and posture of the hind foot of Rhoetosaurus; we recognize that additional parameters (including loading regimes and ichnological data) provide future modelling aspects to further our understanding of Rhoetosaurus pedal biomechanics.

Dessine-moi une courbe de diversité des conodontes

Emilia Jarochowska

GeoZentrum Nordbayern, Germany

Conodonts underwent a decline in terms of diversity and disparity across the Silurian Period, sharply contrasting with their outstanding diversification in the Ordovician.  Abiotic factors have been invoked as the main controls over Silurian conodont turnover at the regional scale, but the mechanism of this purported control is unclear.  In order to formulate testable hypotheses concerning conodont diversity, a measure of turnover and an understanding of its spatial scale are required.  The Silurian (uppermost Telychian through Ludfordian) succession of Gotland, Sweden, provides an unparalleled opportunity to quantify local (sample and habitat) and regional components of conodont diversity, thanks to four decades of exhaustive sampling by the late Lennart Jeppsson.  A succession of coeval assemblages derived from a range of environments allows us to quantify community turnover and track environmental niches of individual species across an interval of c. 10 million years, and ultimately offers a chance to translate local ecological processes into macroevolutionary patterns.

A new key Smithian (Early Triassic) quantitative ammonoid biochronology from the western USA basin

Romain Jattiot^1,2, Hugo Bucher¹, Arnaud Brayard², Morgane Brosse¹, Jim Jenks³ and Kevin Bylund³

¹University of Zurich, Switzerland
²CNRS UMR 6282, Université de Bourgogne Franche Comté, France
³Independent

Since the pioneering work of Silberling and Tozer (1968), the western USA basin has been known to include an excellent record of Smithian ammonoids.  The Smithian is a crucial time interval, recording the first global, major diversification–extinction cycle after the Permian–Triassic boundary mass extinction.  Our intensive sampling of the lower portion of the Thaynes Group in the Palomino Ridge area (northeastern Nevada) yielded abundant and well-preserved Smithian ammonoid faunas.  Based on new data from Palomino Ridge and previous data from neighbouring localities in Utah, we present the first quantitative Smithian ammonoid biochronological scheme for the western USA basin.  The biochronological sequence comprises five unitary association zones that can be correlated with other localities from the Northern Indian Margin.  Three unitary association zones (UAZ1, UAZ2 and UAZ3) are defined for the early Smithian, one (UAZ4) spans the entire middle Smithian and one (UAZ5) comes into the first part of the Late Smithian.  Finally, a provisional UAZ6 could represent the second part of the Late Smithian.  This zonation stands in contrast to the 14 Smithian unitary association zones previously established in the Northern Indian Margin.  The latter is shaped by much higher turnover rates, especially during the middle Smithian.

Reconstructing the internal anatomy and lifestyle of a Jurassic crustacean from the La Voulte Lagerstätte

Clement Jauvion^1,2, Denis Audo³, Sylvain Charbonnier¹ and Jean Vannier²

¹CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
²CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
³Université de Rennes, France

The La Voulte Konservat-Lagerstätte is a renowned site from the Callovian (Jurassic).  Its exceptionally fine-detailed preservation – in three-dimensional sideritic nodules – yields various fossils, including crustaceans.  X-ray microtomography was applied to an exceptionally preserved specimen of a polychelidan lobster to investigate its external and internal anatomy.  Polychelidans are fascinating crustaceans that were known from their fossils before their extant counterparts were discovered in the deep sea.  They differ from other crustaceans by having four or five pairs of claws.  Although recent palaeontological studies have clarified the systematics and phylogeny of the group, the biology of extant polychelidans and their anatomy are poorly documented.  Numerous aspects of the evolutionary history of the group remain obscure, in particular how and when polychelidans colonized the deep sea and became restricted there.  The revealed key parts of the external and internal anatomy – mouthparts, digestive tract and reproductive organs – of Voulteryon parvulus (Eryonidae) compared with dissected specimens clearly identify this specimen as a female with mature ovaries.  This set of new observations offers new insight into the feeding and reproductive habits of these Mesozoic animals.  Contrary to other Jurassic polychelidan lobsters, V. parvulus spawned, and probably inhabited, relatively deep-water environments, as do extant polychelidans.

Development origin of the synarcual in jawed vertebrates: implications for vertebral development and fusion

Zerina Johanson¹, Catherine Boisvert², Kate Trinajstic² and Peter Currie³

¹Natural History Museum, London, UK
²Curtin University, Australia
³Australian Regenerative Medicine Institute, Australia

The synarcual is a structure incorporating multiple elements of two or more anterior vertebrae of the axial skeleton, forming immediately posterior to the cranium.  It has been convergently acquired in the fossil group ‘Placodermi’, in Chondrichthyes (Holocephali, Batoidea), and to varying degrees in certain mammalian taxa.  Examination of early developmental stages indicates that in the Batoidea and the ‘Placodermi’, individual vertebrae developed normally and only later become incorporated into the synarcual, implying regular somite segmentation and vertebral development.  Here we show that in the holocephalan Callorhinchus milii, uniform and regular vertebral segmentation also occurs, with anterior individual vertebra developing separately with subsequent fusion into a synarcual.  Vertebral elements forming directly behind the synarcual continue to be incorporated into the synarcual through growth.  This appears to be a common pattern through the Vertebrata.  Our observations on synarcual development in three major groups of early jawed vertebrates also indicate that fusion involves heterotopic cartilage and perichondral bone/mineralized cartilage developing outside the regular skeleton.  We suggest that chondrichthyans have potential as ideal extant models for identifying the genes involved in these processes and to better understand the evolution of regionalization in vertebrates.

Anti-predation strategy, growth rate and extinction amongst Pliocene scallops of the US eastern seaboard

Andrew Johnson¹, Annemarie Valentine², Melanie Leng³, Hilary Sloane³, Bernd Schöne⁴ and Donna Surge⁵

¹University of Derby, UK
²Newcastle University London, UK
³British Geological Survey, UK
⁴University of Mainz, Germany
⁵University of North Carolina, USA

Placopecten, Chesapecten and Carolinapecten are scallop (pectinid bivalve) genera occurring in the Pliocene of the US eastern seaboard.  The first, present in the area today, is a smooth, streamlined form, adept at escaping predators by swimming (‘flight’ strategy).  The other two, which are extinct, are plicate (‘ribbed’) forms.  Plication facilitates a ‘resistance’ strategy towards predators which is benefited by large size and high shell thickness – maximally so if these states are achieved early in life.  Oxygen isotope profiles show that early ontogenetic extensional growth in Pliocene Placopecten was at the same moderate rate as in modern Placopecten.  By contrast, in Chesapecten it was as fast as in the fastest-growing modern scallop (c. 80 mm per annum), and accompanied by development of an unusually thick shell, while in Carolinapecten it was substantially faster still (>140 mm per annum).  Rapid growth in Chesapecten and Carolinapecten was probably enabled by high primary productivity, for which there is evidence from carbon isotope data, sediment composition and the associated biota.  The extinction of Chesapecten and Carolinapecten, and the survival of Placopecten, can be attributed to a decline in primary productivity which prevented a maximally effective ‘resistance’ strategy towards predators but had no deleterious impact on a ‘flight’ strategy.

Palaeoneuroanatomy of Phuwiangosaurus sirindhornae from the Sao Khua Formation in Thailand

Siripat Kaikaew, Suravech Suteethorn, Uthumporn Deesri and Varavudh Suteethorn

Mahasarakham University, Thailand

A very well-preserved and nearly complete braincase of Phuwiangosaurus sirindhornae has been discovered in the Early Cretaceous red beds of the Sao Khua Formation in Kalasin province, northeastern Thailand.  It has been studied using computed tomographic techniques to generate three-dimensional models.  The internal structure and endocast were compared with other sauropods.  The endosseous labyrinth shows a close affinity to that of Camarasaurus.

Evolution of animal behaviour in the Ediacaran–Cambrian transition

Charlotte G. Kenchington¹ and Duncan McIlroy^1,2

¹Memorial University of Newfoundland, Canada
²Bonne Bay Marine Station, Canada

The transition from the Ediacaran to the Cambrian (~541 million years ago) marks a fundamental leap in the evolution of life: the evolution of complex animal behaviour, the decline in the microbial mats that characterised the Neoproterozoic, and a drastic change in the chemistry of the sediment–water interface.  Disturbance is well known as a controlling factor in structuring modern communities.  By combining detailed petrographic analysis with data on sedimentology, burrow densities, and ichnodiversity of the basal Cambrian stratotype we are able to place the evolution of animal behaviour recorded in these successions into an improved palaeoenvironmental context.  Additionally, Ediacaran–Cambrian ichnofabrics are found to be comparable to experimentally produced ones created by simple ecdysozoans and lophotrochozoans collected from the dysoxic sediments of the Bonne Bay fjords of western Newfoundland.  Using multivariate statistical analyses, it is possible to identify and quantify any correlation between palaeoenviromental, ichnological and matground characteristics.  This will create improved understanding of the interplay between biological and abiological processes during the evolution of complex animal behaviour in a palaeoenvironmental context.

Molecular evidence for a delayed emergence of modern squamates in the Middle to Late Jurassic

*Catherine Klein, Matthew A. Wills and Nicholas R. Longrich

University of Bath, UK

Squamates (snakes, lizards and amphisbaenians) diverged from rhynchocephalians near the Permo–Triassic boundary.  Their fossil record remains depauperate until the Cretaceous, producing extensive ghost ranges on phylogenies.  Consequently, little is known of early squamate evolution.  The oldest definitive fossils of crown squamates are Jurassic in age.  On the basis of previous molecular clock models it has been estimated that this crown group originated near the Triassic–Jurassic boundary.  Here we apply relaxed molecular clock models to existing trees and reveal that crown squamates may have originated later.  Ten outgroup taxa and up to 44 calibration points are used, as multiple outgroup taxa and numerous calibration points are key to having a well-informed clock.  The results suggest that basal divergences within squamates may have occurred in the Middle to Late Jurassic.  This is consistent with the emerging pattern of vertebrates undergoing Mid-to-Late Jurassic radiations, observed so far in mammals, dinosaurs and pterosaurs.  It also supports the suggestion that the Jurassic was an important period of diversification and evolutionary innovation.

Arumberiamorph structures discovered in modern microbial mats

*Anton V. Kolesnikov^1,2, Taniel Danelian², Maxime Gommeaux³, Andrey Maslov⁴ and Dmitriy V. Grazhdankin^1,5

¹Trofimuk Institute of Petroleum Geology and Geophysics, RAS, Russia
²CNRS UMR 8198, Université de Lille, France
³Université de Reims Champagne-Ardenne, France
⁴Zavaritsky Institute of Geology and Geochemistry, RAS, Russia
⁵Novosibirsk State University, Russia

During the study of modern halotolerant microbial mats in salterns near the village of Kervalet, western France we observed fanning-out and curved series of macroscopic ridges on the surface on a newly formed biofilm.  The structure resembles the late Ediacaran fossil Arumberia which is widely distributed in Australia, Avalonia, Baltica, Siberia and India, and it is always confined to intertidal delta-plain settings subject to fluctuating salinity conditions and periodic desiccation.  Although the origin of the structure observed in modern microbial mats remains enigmatic, wrinkled and rugose variants of microbial biofilms exhibit, in general, increased levels of resistance to several environmental stresses.  By analogy, the fossil Arumberia could be interpreted as a microbial mat morphotype developed in response to environmental perturbations in terminal Ediacaran shallow marine basins.  If environmental conditions are likely to be responsible for the formation of Arumberia, it is then not that a specific biological community has survived since the Ediacaran – it is that the biological response of microbial communities that manifested itself quite commonly in certain terminal Ediacaran and early Cambrian environments can still be found today.

Palaeozoic acritarch diversity

David M. Kröck¹, Hendrik Nowak², Claude Monnet¹ and Thomas Servais¹

¹CNRS UMR 8198, Université de Lille, France
²Naturmuseum Südtirol, Italy

Most Palaeozoic acritarchs are thought to represent part of the marine phytoplankton and therefore may constitute a significant element at the base of the marine trophic chain during the Cambrian explosion and the subsequent Great Ordovician Biodiversification Event.  It has been argued that a higher concentration of phytoplankton in the early Palaeozoic oceans triggered these major evolutionary events and had an important impact on metazoan diversification.  The expanding and increasingly diverse phytoplankton could have served as food for the developing zooplankton, but also for various clades of suspension feeders and detritus-feeding organisms.  Acritarch diversity remained high from the Ordovician to the Devonian.  However, during the Devonian–Carboniferous boundary interval acritarch biodiversity significantly decreased, although a collapse of the marine food web is not observed in the fossil record.  Here we present a new research project, based on a PhD research programme, to analyse the phytoplankton dynamics during the entire Palaeozoic.  Similar to a prior study on Cambrian acritarch diversity (Nowak et al. 2016), we propose to reconstruct taxonomic diversity and disparity trends that can be compared with the biodiversity of marine invertebrates during the Palaeozoic.  We will attempt to compile a complete database and calculate various diversity indices at global and regional scales.

RNames – a new stratigraphical database and a tool for occurrence-based palaeobiological analyses

Björn Kröger and Kari Lintulaakso

University of Helsinki, Finnish Museum of Natural History, Finland

RNames (<http://rnames.luomus.fi/>) is an open-access relational database linking stratigraphic units with others that are considered to be time-equivalent or time-overlapping.  RNames is also a tool to correlate amongst stratigraphic units.  The structure of the database allows for a wide range of queries and applications.  Currently three algorithms are available, which calculate a set of correlation tables with Ordovician stratigraphic units, time binned into high-resolution chronostratigraphic slices (Global Stages; Stage Slices; and Time Slices).  The ease of availability of differently binned stratigraphic units and the potential to create new schemes is one of the main advantages and aims of RNames.  Different time-binned stratigraphic units can be matched with other databases and allow for simultaneous up-to-date analyses of stratigraphically constrained estimates in various schemes.  We exemplify these new possibilities with our compiled Ordovician data (+ 4,000 stratigraphic units, + 24,000 stratigraphic opinions, nearly 400 references) and analyse fossil collections of the Paleobiology Database based on the three different binning schemes.  The presented diversity curves are the first sub-stage level global marine diversity curves for the Ordovician.  A comparison among the curves reveals that differences in time slicing have a major effect on the shape of the curve.

Modelling the pattern of preservation of vetulicolians from the Cambrian Chengjiang Biota

*Yujing LI^1,2, Sarah E. Gabbott², Peiyun Cong^1,3 and Xianguang Hou¹

¹Yunnan University, China
²University of Leicester, UK
³Natural History Museum, London, UK

Vetulicolians are an enigmatic fossil group characterised by a bursiform anterior body (normally bearing five pairs of lateral pouches) and a segmented/annulated posterior body that, at least superficially, resembles that of arthropods.  This unusual bodyplan and lack of information about anatomical structures within the anterior body make the interpretation of these animals problematic, with proposed affinities varying from unusual arthropods, stem-group deuterostomes, relatives of the tunicates, or chordates.  Here we evaluate patterns of preservation across specimens and between localities, and quantify morphological characteristics for vetulicolians from the Chengjiang biota, to investigate how specific characters may be preserved or lost/decayed in the preservation sequence.  This approach may elucidate their true taxonomic affinities.

Cambrian origin of mitrates (Echinodermata, Stylophora): new evidence from the Furongian of Korea and South China

Bertrand Lefebvre¹, Guiying Chen², Seung-Bae Lee³, Fleur Noailles⁴, Samuel Zamora⁵ and Xuejian Zhu⁶

¹CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
²Guilin University of Technology, China
³Korea Institute of Geoscience and Mineral Resources, Korea
⁴Monash University, Australia
⁵Instituto Geológico y Minero de España, Spain
⁶Nanjing Institute of Geology and Palaeontology, CAS, China

Stylophorans are a clade of Palaeozoic echinoderms (middle Cambrian-Pennsylvanian) with a single feeding arm (aulacophore) and a flattened, fundamentally asymmetrical body (theca).  In recent years, the traditional subdivision of the class Stylophora into the two orders Cornuta and Mitrata was questioned by several phylogenetic analyses, suggesting that (monophyletic) mitrates may derive from (paraphyletic) cornutes.  Until recently, however, tackling phylogenetic relationships within stylophorans was seriously hampered by their limited Cambrian fossil record (especially in the Furongian) and apparently rapid diversification in Early Ordovician times.  In the early 2000s, abundant, exquisitely preserved stylophorans were collected in the Furongian of Guangxi Zhuang Autonomous Region, South China (Sandu Formation, Jiangshanian) and Korea (Dongjeom Formation, Stage 10).  The careful examination of this material shows that it contains the oldest known undisputable remains of the three main clades of mitrates (lagynocystids, mitrocystitids and peltocystids) and, more importantly, that the morphology of these stylophorans shows a mixture of cothurnocystid (cornute-like) and more advanced (mitrate-like) features.  These results not only confirm the paraphyly of cornutes, but they also suggest that the diversification of mitrates began in the Furongian.  Consequently, their apparent rapid radiation in Early Ordovician times was largely the consequence of a poor late Cambrian fossil record.

A new solutan (Echinodermata, Blastozoa) from the Guzhangian (Cambrian Series 3) Weeks Formation of Utah, USA: evolutionary and palaeogeographic implications

Bertrand Lefebvre¹ and Rudy Lerosey-Aubril²

¹CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
²University of New England, Australia

A new solutan echinoderm is described from the upper part of the Weeks Formation (Guzhangian).  The Cambrian (Series 3) succession of the central House Range in western Utah (USA) documents the early diversification of the class Soluta, which is characterised by a major ecological transition from sessile, ‘pelmatozoan’ primitive taxa (Coleicarpus, Wheeler Formation) to more and more vagile, temporarily attached (Castericystis, Marjum Formation) to mostly unattached, ‘homalozoan’ derived forms (new solutan, Weeks Formation).  Although the fossil record of solutans remains patchy, the currently available data strongly speak to a Laurentian origin for this class in middle Cambrian times.  The morphology of the Weeks solutan is remarkably intermediate between those of Castericystis and Minervaecystis.  Its twisted, flattened dististele possibly represents an adaptation for a more efficient crawling atop soft substrates.  This morphological feature also questions the phylogenetic relationships between syringocrinid and dendrocystitid solutans, and the possible evolution of the latter from basal Minervaecystis-like syringocrinids by paedomorphosis.

Exceptional late Cambrian fossils from McKay Group (British Columbia, Canada)

Rudy Lerosey-Aubril¹, Stacey Gibb¹, John R. Paterson² and Brian D. E. Chatterton²

¹University of New England, Australia
²University of Alberta, Canada

Documentation of non-biomineralizing animals that lived in the Furongian is essential for a comprehensive understanding of the diversification dynamics of early metazoans.  Here we report new occurrences of exceptional preservation in Furongian strata of the McKay Group near Cranbrook, British Columbia, Canada.  This locality has already yielded trilobites with phosphatized guts, all of the same species from the same interval.  Two new horizons with soft-tissue preservation are documented; one has yielded a trilobite with an exquisitely-preserved gut belonging to a different species, the other a ctenophore and an aglaspidid arthropod.  The ctenophore represents the first Furongian record of the phylum and the first occurrence of Burgess Shale-type preservation in the late Cambrian of Laurentia.  The aglaspidid is atypical in having twelve trunk tergites and a narrow ‘tailspine’.  The bearing of these features on the evolution of aglaspidid trunk tagmosis and the composition of aglaspidid exoskeleton will be discussed.  The trilobite reveals previously unknown gut features, possibly related to enhanced capabilities for food processing.  The fact that exceptional preservation is both stratigraphically more widespread and taxonomically more diverse in these deposits than previously realised offers promising perspectives for the study of the c. 600-m-thick unexplored part of the section.

New exceptionally-preserved arthropods from the middle Cambrian of Utah and Nevada, USA

Rudy Lerosey-Aubril¹, Andries Weug² and Jake Skabelund²

¹University of New England, Australia
²Independent

The Great Basin region of the western United States is home to nine Cambrian Konservat-Lagerstätten.  None of them competes with the celebrated Burgess Shale (middle Cambrian, Canada) regarding the abundance of exceptionally-preserved fossils, but with time some have yielded rather diverse biotas.  Still, new discoveries of exceptional material in these deposits remain important, for most of the non-biomineralizing taxa are known from a few incomplete specimens.  Here we present exceptionally-preserved arthropods recently discovered in middle Cambrian strata of the Great Basin region.  A specimen from the Pioche Formation (Nevada), apparently preserving nervous structures, represents the first occurrence of Alalcomenaeus (Megacheira) in this region.  The Wheeler Formation (Utah) has yielded a large new taxon, characterised by hook-shaped pleurae and possibly related to Sanctacaris.  The other fossils were recovered from the Marjum Formation (Utah).  This includes a new arthropod displaying cephalic appendages with two antenniform branches, a median eye, and phosphatized digestive glands.  Similarly phosphatized guts are described in specimens of Modocia (Trilobita) – these are the first examples of preservation of internal organs via phosphatization in this Konservat-Lagerstätte.  An agnostid displaying cephalic appendages and a well-preserved specimen of Naraoia, the fifth to be found in these deposits, are also documented.

Filamentous fossils within the Ediacaran macrobiota: reproduction, construction and palaeoecology

Alex Liu

University of Cambridge, UK

Late Ediacaran (~580–560 Ma) fossil assemblages from Newfoundland, Canada, reveal abundant, previously undescribed macroscopic filamentous fossils within benthic deep-marine palaeocommunities.  Filamentous structures occur in densities of hundreds per square metre, and exhibit a range of morphologies.  Some filaments of centimetres to decimetres in length are observed to attach frondose organisms to the substrate, and represent a novel body plan within that group.  Other filaments, of a few millimetres to several metres in length, traverse bedding surfaces, can bifurcate, and seemingly connect individual macro-organisms, potentially providing fossil evidence for a recently hypothesized stolon-like reproductive strategy within some Ediacaran taxa.  Similar filamentous impressions from the Ediacara Member of South Australia, and the Charnian Supergroup of Charnwood Forest (UK), demonstrate filamentous structures to be a widespread and prominent component of global Ediacaran macrofossil assemblages.  Study of the spatial relationships between filamentous structures and contemporaneous macrofossil taxa offers a new avenue via which to investigate aspects of Ediacaran palaeoecology.  Importantly, the close association of certain macrofossil taxa with filamentous impressions offers novel means by which to constrain their phylogenetic positions.

High diversity of small dinosaurs preceding the Cretaceous-Palaeogene (K-Pg) mass extinction

Nicholas R. Longrich

University of Bath, UK

Dinosaurs dominated on land for almost 150 million years, before disappearing at the end of the Cretaceous, 66 million years ago.  Based on the best-known late Maastrichtian dinosaur assemblage, the Lancian fauna of western North America, it has been assumed that Maastrichtian dinosaur faunas were low in diversity and dominated by large species.  However, small dinosaurs rarely preserve and tend to receive less attention, suggesting that these patterns may result from biases in preservation and study.  A study of small dinosaurs from North America shows that a diverse fauna of small dinosaurs thrived alongside giants such as T. rex and Triceratops.  New species of small Dromaeosauridae, Troodontidae, Caenagnathidae, Alvarezsauridae and Ornithischia are documented here.  Total diversity includes 38 species ranging from 2 to 50,000 kg, occupying carnivorous, herbivorous, insectivorous and piscivorous roles; most (60 %) weighed ³1,000 kg and many (40 %) weighed ³100 kg.  Hatchling Tyrannosaurus, Nanotyrannus, Triceratops and Edmontosaurus are present, emphasizing the role of juveniles in the food chain.  Lancian dinosaurs exploited a remarkable range of niches, to a greater degree than almost any other fauna.  These patterns are consistent with a catastrophic extinction of dinosaurs at the K-Pg boundary, driven by the Chicxulub impact.

A molecular palaeobiological investigation into arthropod terrestrialization

Jesus Lozano-Fernandez¹, Robert Carton², Alastair R. Tanner¹, Mark N. Puttick¹, Mark Blaxter³, Jakob Vinther¹, Jørgen Olesen⁴, Gonzalo Giribet⁵, Gregory D. Edgecombe⁶ and Davide Pisani¹

¹University of Bristol, UK
²National University of Ireland, Maynooth, Ireland
³University of Edinburgh
⁴Natural History Museum of Denmark, Denmark
⁵Harvard University, USA
⁶Natural History Museum, London, UK

Animals have marine origins and only a few phyla contain fully terrestrial lineages.  The process through which animals adapted to life on land is referred to as terrestrialization, and is an extreme case of adaptation.  Arthropoda represent the largest majority of terrestrial biodiversity and have an extensive fossil record that suggests they were the first terrestrial animals.  Arthropods colonized the land multiple times independently, allowing rigorous comparison of the alternative solutions adopted by the different groups to the same adaptive challenge.  In this study we implemented a molecular palaeobiological approach, merging molecular and fossil evidence, to elucidate the deepest history of the terrestrial arthropods.  We focused on the three, independent, Palaeozoic arthropod terrestrialization events (Myriapoda, Hexapoda and Arachnida) and showed that a marine route to the colonization of land is the most likely scenario.  Molecular clock analyses confirmed an origin for the three terrestrial lineages bracketed between the Cambrian and Silurian.  While molecular divergence times for Arachnida are consistent with the fossil record, Myriapoda and Hexapoda are inferred to have colonized land earlier.  An estimated origin of myriapods by the early Cambrian substantially predates trace or body fossil evidence, and raises the possibility of independent terrestrialization events in crown-group myriapods.

Two new enigmatic worms from the Chengjiang biota

Xiaoya Ma^1,2

¹Yunnan University, China
²Natural History Museum, London, UK

The fossilization of vermiform animals is relatively rare due to their soft bodies, which is why they only occur in some exceptionally preserved fossil assemblages, such as the early Cambrian Chengjiang Lagerstätte.  Despite the great diversity of vermiform species recovered from the Chengjiang Lagerstätte, almost all of them are assigned to Priapulida or its close relatives, which were once dominant members of the benthic fauna in Cambrian marine communities.  However, there is still little known about the early evolution of other vermiform phyla and their lifestyles.  This study reports and describes two new non-priapulid vermiform taxa from the Chengjiang Lagerstätte.  The fossils are very rare, as only one specimen has been discovered for each species in over 30 years of collecting.  However, the specimens show distinct features that distinguish them from other reported fossil worms.  For example, one of the species shows a close resemblance to acanthocephalans.  Although the taxonomic and phylogenetic position of both new worms remains enigmatic, they expand both the biodiversity and ecological diversity of known early Cambrian ecosystems.

A case of mass mortality of large trilobites in the Fezouata Shale (Lower Ordovician, Morocco): evidence for benthic hypoxic episodes?

*Emmanuel L. O. Martin¹ and Rudy Lerosey-Aubril²

¹CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
²University of New England, Australia

The discovery of the Fezouata biota (Early Ordovician, Morocco) represents a major breakthrough in our understanding of the early Palaeozoic diversification of animals.  Yet, little is known of the environmental and early diagenetic contexts that facilitated its preservation.  A taphonomic approach to the preserved assemblages might prove informative in this regard, as illustrated herein with the study of a cluster of large trilobites.  The monospecific assemblage comprises 92 remains of Platypeltoides magrebiensis, the only fossils found on a bedding surface c. 25 m² in size.  They display various degrees of articulation, 39.3 % of them representing fully (FA) or partially (PA) articulated exoskeletons.  Width frequency distribution is normal and restricted (4.5–11.5 cm), with no obvious difference between FA or PA specimens and isolated sclerites; this suggests a biologically-induced size-sorting.  Limited to null transport is also indicated by the absence of preferential horizontal and dorsum orientations.  No clear preferential facing direction of FA specimens is observed, but these specimens are predominantly (75 %) dorsum-down.  The absence of body flexure, the preservation on a single plane, and this preferential dorsum-down orientation suggest that the 20 FA individuals died before burial.  This census-assemblage documents a mass mortality event, probably resulting from an episode of benthic hypoxia.

Virtual visits to past environments in learning programmes for university students

Edoardo Martinetto^1,2,3, Emanuel Tschopp¹ and Robert A. Gastaldo⁴

¹Università degli Studi di Torino, Italy
²Universidade Nova de Lisboa, Portugal
³Museu da Lourinha, Portugal
⁴Colby College, USA

Direct contact with nature has an important impact on people’s desire to study and protect the environment.  Likewise, learning programmes about palaeoenvironmental research can be supplemented by virtual visits to geological contexts rich in ancient records.  Personal visits create emotions, and combining them with scientific instructions is a powerful teaching strategy.  Therefore, we have started to build an international course on past environments aiming to illustrate steps in the history of nature, with the contribution of leading experts on different topics.  The course will include 16 lecture units of c. 700 slides with a focus on terrestrial palaeoenvironments.  Outstanding features and transformations of natural systems will be shown by telling stories of key sites and particular geological contexts.  The learning programme is intended to be: attractive for students, simulating a walk through nature; up to date and scientifically correct, including artistic reconstructions of the highest fidelity; and have a special focus on lesser-known and less conventional topics from around the world.  The project is still a work in progress and open to contributions from the palaeontological community.  The combination of different experts from various research fields in palaeontology promises to lead to a highly interesting and innovative teaching programme for an international audience.

Deep life in deep time: the palaeobiology of the subsurface

Sean McMahon¹, John Parnell² and Ashleigh van Smeerdijk Hood¹

¹Yale University, USA
²University of Aberdeen, UK

Palaeobiology is traditionally concerned with the history of life on Earth.  In recent decades, however, samples from mines and boreholes have revealed that our planet’s biosphere extends several kilometres downwards below the seafloor and land surface.  Deep pores and fractures host vast numbers of bacteria, archaea, fungi and microinvertebrates; ‘life in Earth’ may exceed 20% of the planet’s biomass (McMahon and Parnell 2014).  Although the contemporary deep biosphere is the subject of major research efforts, scant attention has been paid to its shifting size, activity and interaction with biogeochemical cycles throughout Earth’s history.  We contend that palaeobiologists should therefore turn their attention to the subsurface.  The fossil record of deep life includes mineralized cellular remains, borings, and isotopic anomalies, but is drastically undersampled.  Here we present: new heavy-metal isotopic evidence from Devonian, Permian and Triassic reduction spheroids consistent with a subsurface bacterial origin; a new estimate for the present continental subsurface biomass, based on the latest cell counts and models of crustal groundwater distribution, with implications for biomass distribution through Earth’s history; and preliminary results from a new model of H₂ production by mineral radioactivity, an important subsurface energy source.

Phylogeny and origin of Giraffidae based on characters of the bony labyrinth

Bastien Mennecart¹, Maria Rios Ibanez³, Gertrud E. Rössner² and Loïc Costeur¹

¹Naturhistorisches Museum Basel, Switzerland
²Bayerische Staatssammlung für Paläontologie und Geologie, Germany
³Spanish National Research Council, Madrid, Spain

The living family Giraffidae with its two genera Giraffa and Okapia has a long evolutionary history spanning most of the last 15 Ma.  The family is known from a plethora of fossil taxa across the whole Old World from Eurasia to Africa.  Giraffes are the only ruminants to bear two to five epiphyseal permanent cranial appendages, the ossicones.  A further characteristic of the family is the presence of a bilobed lower canine which is widely used to diagnose extinct members.  Despite this apparent wealth of data, little is known as to the origin of Giraffidae.  A number of taxa bearing ossicone-like cranial appendages, such as the Palaeomerycidae and their North American relatives the Dromomerycinae, or branched or flattened cranial appendages such as the Climacoceratidae, have been variously related to giraffids, but without any consensus.  We ran a preliminary cladistics analysis based on the bony labyrinth of Giraffidae and the above-mentioned problematic fossil taxa.  It showed that the bony labyrinth is a powerful structure for the phylogeny of ruminants.  Some morphological characteristics (cochlear morphology and orientation of the vestibular aqueduct) are unique to Giraffidae among the ruminants and give insights into the phylogeny and origin of this iconic group.

Plesiosaur remains from the Lower Jurassic part of the Kap Stewart Formation, Jameson Land, East Greenland – evidence of the earliest marine incursion

Jesper Milàn^1,5, Octávio Mateus^2,3, Marco Marzola^2,3,4 and Lars B. Clemmensen⁶

¹Geomuseum Faxe, Denmark
²Museu da Lourinhã, Portugal
³Universidade Nova de Lisboa, Portugal
⁴Geocenter Møns Klint, Denmark
⁵Natural History Museum of Denmark, Denmark
⁶University of Copenhagen, Denmark

Two dorsal vertebrae and one dorsal rib were collected at a mountain ridge in the Kap Stewart Formation at Carlsberg Fjord, near Lepidopteris Elv, at Jameson Land, East Greenland, during the 2012 and 2016 Geocenter Møns Klint Dinosaur Expeditions.  The Kap Stewart Formation is Rhaetian to Sinemurian in age, and the bones were found in the middle of the Formation, corresponding to the Hettangian part of the Formation.  The collected bones show clear plesiosaur affinities: amphicoelous centra, paired ventral nutritive foramina in the centrum, unfused neurocentral sutures and single headed ribs.  The diameter of the centra is 2 cm indicating a small-sized individual.  Plesiosaurs are exclusively marine animals and this find represents the first undoubtedly marine vertebrate, in contrast to previous records of hybodont sharks and turtles in the synrift Mesozoic deposits in Greenland, and witnesses the earliest stages of the opening of the North Atlantic at 44° palaeolatitude.

The fish and the Fishclay – an old story revealed

Jesper Milàn^1,2 and Werner Schwarzhans²

¹Geomuseum Faxe, Denmark
²Natural History Museum of Denmark, Denmark

The famous K-Pg boundary strata at the UNESCO World Heritage Site, Stevns Klint, eastern Denmark is composed of a thin clay layer called the Fishclay.  Despite the name, to date only one partly-articulated fish skeleton is known to have been recovered from the Fishclay; however, scales and singular skeletal elements are quite common.  The specimen in question consists of a partially-preserved articulated skeleton of a probable Berycoid fish.  Unfortunately, the head and tail with the prime diagnostic characters are missing, preventing a more specific identification.  This study traces the origins of the Fishclay name and boundary strata from the very first description of Stevns Klint in 1759 by Abilgaard to the first occurrence of the name Fishclay in 1849 by Forchhammer.  Interestingly, the same paper that introduced the name Fishclay also very briefly mentioned the existence of a partially preserved articulated skeleton of a small fish, the fish skeleton that has proven to be the only one known to exist from the Fishclay!

Tiering and competition in Mistaken Point Ediacaran communities

*Emily G. Mitchell¹ and Charlotte G. Kenchington²

¹University of Cambridge, UK
²Memorial University of Newfoundland, Canada

Bedding-plane assemblages of Ediacaran fossils at Mistaken Point, Newfoundland (~565 Ma), are among the oldest known examples of macroscopic communities.  These immobile organisms are preserved in situ, allowing spatial analyses to shed light on organism ecology.  Competition for vertical space has been suggested to be the primary community structuring mechanism resulting in different taxa occupying different parts of the water column, known as tiering.  The community structure of the four most diverse Mistaken Point communities (‘D’, ‘E’, ‘G’ and Lower Mistaken Point (LMP) surfaces) was examined using a combination of spatial analyses incorporating morphological variables and tiering metrics.  Spatial analyses offer a way to identify inter- and intra-specific segregation, enabling resolution of the magnitude and type of competition.  Tiering was quantified in terms of the overlap of specimen height.  We found that tiering overlap decreases from the D to G to E to LMP surfaces but instances of large-scale spatial segregation become more frequent, suggesting an increase in the extent of resource competition.  Additionally, specimens with larger discs are more strongly segregated than tall specimens despite occupying different vertical tiers.  These findings suggest that competition for laterally-distributed resources played a major or even dominant role in structuring these ancient communities.

Early Cretaceous vertebrates from the Xinlong Formation of Guangxi, southern China

Jinyou Mo¹, Eric Buffetaut², Haiyan Tong^3,4, Romain Amiot⁵, Lionel Cavin⁶, Gilles Cuny⁵, Varavudh Suteethorn³ and Suravech Suteethorn³

¹Natural History Museum of Guangxi, China
²CNRS UMR 8538, Ecole Normale Supérieure de Paris, France
³Mahasarakham University, Thailand
⁴Institute of Vertebrate Paleontology and Paleoanthropology, CAS, China
⁵CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
⁶Natural History Museum of Geneva, Switzerland

The vertebrate assemblage from the Early Cretaceous non-marine Xinlong Formation of the Napai Basin, in the southwestern part of Guangxi Zhuang Autonomous Region (southern China), includes chondrichthyans, actinopterygians, turtles, crocodilians and dinosaurs.  This assemblage shows many similarities to those from non-marine formations of the Khorat Group of northeastern Thailand.  It also seems to be particularly close to that from the Khok Kruat Formation, considered as Aptian in age, as shown especially by sharks and turtles and by the presence of iguanodontians.  An Aptian age is therefore proposed for the Xinlong Formation.  Stable isotopes suggest that this part of South China experienced subtropical arid conditions during the deposition of the Xinlong Formation.  In its composition, the vertebrate fauna from the Xinlong Formation seems to be more similar to coeval faunas from Southeast Asia than to assemblages from northern China.  Although this may partly reflect different depositional and taphonomic environments, it seems likely that, during Early Cretaceous time, southern China and Southeast Asia were part of a distinct zoogeographical province, different from that corresponding to northern China.  This may be the result of both climatic differences and geographical barriers such as mountain chains.

Biostratigraphy and geometric morphometrics of conchostracans (Crustacea, Branchiopoda) from the Late Triassic fissure deposits of Cromhall Quarry

Jacob Morton¹, David I. Whiteside¹, Manja Hethke², Michael J. Benton¹

¹University of Bristol, UK
²Freie Universität Berlin, Germany

The enigmatic fissure deposits of southeast England and southern Wales are famous for their unique assemblage of Late Triassic vertebrates, although their age is contentious.  While recent studies of palynomorphs have dated some as Rhaetian, their conchostracan (Crustacea, Branchiopoda) assemblages have not been described or used in biostratigraphy.  We find that species determination of British Late Triassic conchostracans requires detailed observations of both shape and ornamentation.  We provide evidence that brodieana is a subspecies of Euestheria minuta, the traditional view, rather than a distinct species.  Finally, we find no distinction between conchostracans from bedded Rhaetian deposits of the UK and specimens collected from the fissure deposits of Cromhall Quarry, Gloucestershire, supporting a late Rhaetian age for these deposits.

Hyoliths are Palaeozoic lophophorates

*Joseph Moysiuk¹, Martin R. Smith² and Jean-Bernard Caron^1,3

¹University of Toronto, Canada
²Durham University, UK
³Royal Ontario Museum, Canada

Hyoliths – orthothecids and hyolithids – are abundant and globally distributed Palaeozoic ‘shelly’ fossils.  The phylogenetic position of this group has remained unresolved, largely because of the idiosyncratic hyolith scleritome (operculum, conical shell, and paired ‘helens’ in hyolithids) and poorly understood soft anatomy.  Since they were first described over 175 years ago, hyoliths have most often been regarded as incertae sedis, allied with molluscs or assigned their own phylum.  Here we reinterpret hyoliths based mostly on abundant new specimens of the hyolithid Haplophrentis from the Burgess Shale (Stanley Glacier and Marble Canyon) showing exceptionally preserved soft tissues.  Soft tissue characters include an extendable, gullwing-shaped, tentacle-bearing organ surrounding a central mouth, which we interpret as a lophophore, and a U-shaped digestive tract that ends in a dorsolateral anus.  In combination with opposing bilateral sclerites and a ventrally elongated visceral cavity, these features indicate an affinity with the lophophorates (brachiopods, phoronids and tommotiids), substantially increasing the early disparity of this prominent group.  We interpret Haplophrentis as a semi-sessile epibenthic suspension feeder that used its ‘helens’ to elevate its tubular body above the sea floor.  This study reconfirms the importance of Burgess Shale-type deposits in illuminating the evolutionary history of long-problematic taxa known only from skeletal remains.

Biogeography of the Late Ordovician blastozoan echinoderms

Elise Nardin¹, Bertrand Lefebvre² and Alexandre Pohl³

¹CNRS UMR 5563/ IRD UR 234, Université de Toulouse, France
²CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
³UMR 8212, Université Paris-Saclay, France

The diversity of blastozoan echinoderms echoes the major trends of the Great Ordovician Biodiversification Event, starting with a gradual increase and then flourishing dramatically in the Sandbian.  Their major diversification is strongly related to an increase in longevity and cosmopolitanism.  An exhaustive database of temporal, environmental and geographical occurrences of blastozoans at the species level has been compiled in order to consider the impact of several environmental factors on the Ordovician blastozoan biogeographic evolution.  Ten associations of diverse blastozoans are identified since the mid Ordovician.  The composition of the Baltican and Laurentian associations remains stable through the Ordovician, with main tropical and poleward migrations in the Sandbian and the early Katian, respectively.  The peri-Gondwanan margin hosted two diversity hotspots during the Darriwilian at the origin of later coastal migrations.  During the Katian, the palaeobiogeographical distribution of blastozoans results from the inheritance of a relatively strong provincialism (maintained until the Dapingian), and large-scale migrations along the peri-Gondwanan margins and across the Palaeo–Tethys ocean to reach the shallow water environments of the subpolar peri-Gondwana.  Reconstructed oceanic currents support few of the shortest migration paths and therefore suggest that blastozoans larvae acquired survival abilities to wait before settlement.

New Eocene Coleoid (Cephalopoda) Diversity from Statolith Remains

Pascal Neige¹, Hervé Lapierre² and Didier Merle²

¹CNRS UMR 6282, Université de Bourgogne Franche comté, France
²CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France

New coleoid cephalopods are described from statolith remains from the Middle Eocene (Middle Lutetian) of the Paris Basin.  Fifteen fossil statoliths are identified and assigned to the Sepiidae (Sepia boletzkyi sp. nov.,? Sepia pira sp. nov.), Loliginidae (Loligo clarkei sp. nov.), and Ommastrephidae (genus indet.) families.  The sediments containing these fossils indicate permanent aquatic settings in the infralittoral domain.  These sediments range in age from 46 to 43 Ma.  Analysis of the fossil record of statoliths (from findings described here, together with a review of previously published data) indicates marked biases in our knowledge.  Fossil statoliths are known from as far back as the Early Jurassic (199.3 –190.8 Ma) but surprisingly, to the best of our knowledge, no record occurs in the Cretaceous.  This is a ‘knowledge bias’ and clearly calls for further studies.  Finally, we attempt to compare findings described here with fossils previously used to constrain divergence and/or diversification ages of some coleoid subclades in molecular phylogenies.  This comparison clearly indicates that the new data reported here will challenge some estimated divergence times of coleoid cephalopod subclades.

In Barrande’s footsteps: re-evaluation of four enigmatic Cambro–Ordovician echinoderms from Bohemia (Czech Republic)

Martina Nohejlová¹, Bertrand Lefebvre² and Oldřich Fatka¹

¹Charles University Prague, Czech Republic
²CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France

The eight volumes of Barrande’s Système Silurien du centre de la Bohême (1852–1902) represent a milestone for Palaeozoic biostratigraphy and palaeontology in the Czech Republic.  In volume VII, Barrande (1887) described 26 new genera and 80 new species of Cambro–Ordovician ‘cystidean’ echinoderms.  These taxa are now assigned to eight distinct classes: cinctans, coronoids, diploporitans, eocrinoids, edrioasteroids, rhombiferans, solutans and stylophorans.  The morphology and taxonomic classification of four enigmatic ‘cystidean’ taxa are here re-evaluated, based on observations of Barrande’s original material stored in the collections of the Palaeontological Department of the National Museum, Prague.  Three specimens described as Lapillocystites fragilis Barrande, 1887 represent slightly disarticulated thecae of the edrioasteroid Stromatocystites pentangularis Pompeckj, 1896.  Two specimens classified as Cystidea concomitans Barrande, 1887 are newly interpreted as slightly disarticulated supracentral integument of the cinctan Trochocystites bohemicus Barrande, 1887.  Anomalocystites ensifer Barrande, 1887 was correctly identified as a mitrate stylophoran by Ubaghs (1968), who assigned it to a new genus of uncertain systematic affinities (Spermacystis Ubaghs, 1968).  Re-examination of Barrande’s original material suggests that A. ensifer and Cystidea abscondita Barrande, 1887 both correspond to kirkocystid mitrates (Anatifopsis spp.).

New vertebrate coprolites from the Late Triassic Huai Hin Lat Formation of Thailand

Thanit Nonsrirach, Suravech Suteethorn, Sakboworn Tumpeesuwan, Komsorn Lauprasert and Varavudh Suteethorn

Mahasarakham University, Thailand

A thousand vertebrate coprolites were found from seven outcrops of the Huai Hin Lat Formation (Carnian–Norian age) in Chaiyaphum Province, northeastern Thailand.  The coprolites were deposited in a lacustrine environment.  Most of them are very well preserved.  They were described on the basis of their morphology and eight ichnotaxa were recognized, including Eucoprus ichnosp., Eucoprus cylindratus, Dicynodontocopros maximus, Saurocopros bucklandi, Liassocopros hawkinsi, Heteropolacoprus texaniensis, Bibliocoprus ichnosp. and Hyronocoprous amphipolar.  Two new ichnotaxa were found from this study and named Hyronocoprous khonsanensis and Rhopalocoprous chaiyaphumensis.  The occurrence of Bibliocoprus and Hyroconopros extends their stratigraphic distribution from the Late Pennsylvanian and Permian strata of north-central New Mexico to the Late Triassic strata of Thailand.

When did the Isthmus of Panama form?

Aaron O’Dea

Smithsonian Tropical Research Institute, Panama

Some recent studies suggest that the Isthmus of Panama formed many millions of years earlier than the widely recognized age of 3 Ma, a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas.  Fossil, rock and molecular records provide a cohesive narrative of gradually emerging land and constricting seaways, with formation of the Isthmus of Panama sensu stricto around 2.8 Ma.  No clear evidence exists for an isthmus in place before that time.

Alteration development on Carboniferous fossil remains (Ningxia, northwest China): the calcium–sulfur–iron triangle

Giliane P. Odin^1,2, Véronique Rouchon², Olivier Béthoux² and Dong Ren³

¹University College Cork, Ireland
²CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
³Capital Normal University, China

Conservation of fossil items in palaeontological collections represents a serious issue, especially when samples contain pyrite.  Alteration arises when fossils are exposed to the atmosphere, which promotes oxidation.  At worst, this process can result in the complete destruction of specimens.  Experiments were carried out on fossils from the Upper Carboniferous Xiaheyan locality (Ningxia, China), from which a rich entomofauna is currently being investigated.  Using SEM, XRD and Raman spectroscopy, we compared the initial composition and state of preservation of newly excavated fossiliferous or non-fossiliferous samples with those of ancient collection specimens and artificially-aged specimens.  The obtained data show that a sequence of reactions, involving exogenous calcium from nearby calcite layers and endogenous iron and sulfur from framboidal pyrite located inside the fossils, takes place.  One of the observed outcomes is a crystallization of gypsum (calcium sulfate) inside pre-existing cavities or at the exposed surface.  The mechanical pressure produced by the growth of such crystals can result in severe fragmentation of the fossils.  To help avoid this issue, preventative artificial ageing was attempted.  Our experiments suggest that the chemical composition of the fossil itself has a role in the degradation mechanism.

New insights into the ontogeny, morphology and phylogenetic affinities of machaeridians based on articulated Plumulites

*Luke A. Parry^1,2, Jakob Vinther¹, Gregory D. Edgecombe², Derek E. G. Briggs³ and Peter Van Roy⁴

¹University of Bristol, UK
²Natural History Museum, London, UK
³Yale University, USA
⁴Ghent University, Belgium

Machaeridians were long considered a palaeontological mystery, with their imbricating scleritome composed of alternating inner and outer shell plates having no counterparts in modern fauna.  The discovery of an exceptionally preserved specimen with parapodia and chaetae from the Early Ordovician Fezouata shales confirmed that machaeridians are armoured annelid worms, with each segment bearing paired shell plates.  However, the exact position of machaeridians among annelids remains poorly constrained due to the absence of unequivocal apomorphies linking machaeridians to extant polychaete clades.  We report over one hundred articulated scleritomes of Plumulites cf. tafaenensis from the Tafilalt Biota from the Upper Ordovician of Morocco.  Individuals range in body length from ~10 to 84 mm, allowing an unprecedented insight into the development of the machaeridian scleritome from juveniles to adults.  This material confirms that machaeridians added successive shell plates, and therefore segments, during ontogeny, adding another key character that supports an annelid affinity for machaeridians.  In addition to this material, we report new specimens of Plumulites bengtsoni from Fezouata that preserve new details of non-mineralized tissues.  These specimens provide key evidence for the affinities of these long problematic fossils and phylogenetic analyses place them firmly in the annelid crown group in the aphroditacean total group.

Diversity, ecology and biogeography of Laurentian Radiodonta

*Stephen Pates¹, Allison C. Daley^1,2,3 and Bruce S. Lieberman⁴

¹University of Oxford, UK
²Oxford University Museum of Natural History, UK
³University of Lausanne, Switzerland
⁴University of Kansas, USA

Our understanding of large pelagic predators such as Anomalocaris, Hurdia, Peytoia and Caryosyntrips has increased greatly in recent years.  These stem group arthropods are well known from several Cambrian soft-bodied deposits, with much recent focus on taxa from the Emu Bay Shale (Australia), Chengjiang Biota (China) and Burgess Shale (Canada).  Radiodonta are also an important component of Cambrian soft-bodied faunas from the Great Basin (Utah, Nevada and California, USA) and Kinzers Formation (Pennsylvania, USA).  These were described over a long period of time (1979–2008) and these discoveries were not always integrated with the studies of the last 5–10 years on radiodontan systematics and ecology.  We re-examined all previously described Great Basin and Kinzers radiodontans, along with recently collected new specimens.  This expands the known diversity of Radiodonta in Laurentia.  Further, new morphological features are identified for Hurdia, Caryosyntrips and Anomalocaris, and new species are recognized.  Interpretation of their functional morphology suggests taxa from the Great Basin and the Kinzers possessed a range of ecologies, mirroring what is seen from the Burgess Shale.  Finally, the temporal distribution of Radiodonta in Laurentia supports the previously identified overall trend that Anomalocarididae dominate in older sites whereas Hurdidae dominate in younger ones.

Panderiidae, Hemibarrandiidae, Nileidae (Trilobita): so far, yet so close

*Sofia Pereira^1,2,3, Artur A. Sá^2,3 and Carlos Marques da Silva¹

¹Universidade de Lisboa, Portugal
²Universidade de Trás-os-Montes e Alto Douro, Portugal
³Universidade de Coimbra, Portugal

Panderiidae was originally erected as a subfamily of Illaenidae (Bruton, 1968), but its status and affinity were soon questioned.  The Illaenina revision by Lane and Thomas (1983) suggested that Panderiidae could not even be related to this suborder, but subsequent authors maintained the panderiids inside Illaenina.  In turn, Nileidae was assigned by Chatterton and Fortey (1988) to Asaphina, as a member of the superfamily Cyclopygoidea.  Since then, this view has been largely consensual.  Nonetheless, Whittington (2003) considered that Nileidae should be allied with Illaenidae rather than with Asaphina.  In between Panderiidae and Nileidae, the Hemibarrandiidae is a low-diversity group from the high-latitude peri-Gondwana realm recently revised by Mergl and Kozák (2016).  Although consensually assigned to Panderia Volborth, the species Nilaeus beaumonti Rouault represents a new genus allied to Hemibarrandiidae members.  The detailed morphological study of N. beaumonti has allowed its generic reassessment and led to the recognition of a close relationship between these taxa and members of the Nileidae, with whom they share important characters.  The previous assignment of Panderiidae and Hemibarrandiidae to Illaenina is rejected, the separation of the discussed taxa at order level is not justified, but there are still many unsolved questions related to these enigmatic groups.

British Silurian Myodocope ostracods

Vincent Perrier¹, David J. Siveter², Mark Williams² and Douglas Palmer³

¹CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France
²University of Leicester, UK
³Sedgwick Museum of Earth Sciences, UK

The Silurian myodocope ostracods from Britain comprise six families, twelve genera and twenty-two species, plus three species in open nomenclature.  New material includes representatives of the families Bolbozoidae, Entomozoidae, Cypridinidae and Seminovidae n. fam.  Fine biostratigraphic control allows the development of a myodocopid biozonation for the Wenlock and Ludlow series.  Seven myodocopid biozones are established, from the early Homerian (Wenlock) to the late Ludfordian (Ludlow) stages.  This biozonation allows inter-continental correlation of Silurian successions in Europe, in Arctic Russia and Central Asia.

New remains of Mosasauroidea (Squamata) from the Late Cretaceous of Aude (France)

Martial Plasse¹, Nathalie Bardet¹, Xavier Valentin² and Géraldine Garcia²

¹CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France
²CNRS UMR 7262, Université de Poitiers, France

Mosasaur remains (Squamata) were collected from the Santonian of Aude (southern France), near the bridge of the village of Sougraigne.  The identification of these bones shows the presence of two different genera of similar size.  The cranial bones, some vertebrae, two scapulae and a phalanx are assigned to a Plioplatecarpinae Platecarpus cf. tympaniticus, while the pelvic bones and a femur? are instead referred to a Tylosaurinae.  Two phylogenetic analyses confirmed the affiliation of the Plioplatecarpinae to this clade and a relationship close to the species P. tympaniticus.  Only the presence of the zygosphene–zygantrum complex on the dorsal vertebrae could differentiate it from the species P. tympaniticus.  The range of the genus Platecarpus from the Santonian was hitherto limited to the United States: the material from Sougraigne allows us to expand it to France.  Some taphonomic marks observed on some bones can be attributed to the teeth of sharks (like Squalicorax), teleosts or even mosasaurs.

Palaeoenvironmental changes in the Polish Basin as recorded by plant carbon isotopes and fossil charcoal

*Robyn Pointer¹, Claire M. Belcher¹, Stephen P. Hesselbo¹, Marta Hodbod², Kate Littler¹ and Grzegorz Piefont-family:Arial-BoldMT'>ńkowski²

¹University of Exeter, UK
²Polish Geological Institute, Poland

New carbon isotope and charcoal abundance data from the Polish Basin offer a new insight into Early Jurassic palaeoenvironments.  Following extreme climatic changes and a mass-extinction at the Triassic–Jurassic boundary (~201 Ma), the Early Jurassic (~201-174 Ma) saw continued environmental changes in both the marine and terrestrial realms.  Sedimentary cores recovered from the Polish Basin have allowed us to produce new records of changes in atmospheric and wildfire activity changes using carbon isotope stratigraphy and analyses of fossil charcoal abundance.  Negative carbon isotope excursions are recorded in fossil plant material at the Triassic–Jurassic boundary and during the Toarcian, indicating releases of isotopically light carbon into the ocean-atmosphere reservoir during the Early Jurassic.  Initial analyses of fossil charcoal abundance appear to indicate increases in wildfire activity in the Polish Basin, which seem to coincide with negative carbon isotope excursions.  Previous studies from other sites show a peak in fossil charcoal abundance at the Triassic–Jurassic boundary, coincident with negative carbon isotope excursions.  Our new data allow us to recognize environmental changes and their effects on a local scale within the Polish Basin, as well as to assess these changes on a wider scale by comparison to other Early Jurassic sites around the world.

Uncertain-tree: discriminating among competing approaches to the phylogenetic analysis of phenotype data

*Mark N. Puttick, Joseph E. O’Reilly, Davide Pisani and Philip C. J. Donoghue

University of Bristol, UK

Morphological data provide the only insight into classifying the majority of life’s history, but choosing an appropriate method for the analysis of morphological cladistic matrices remains debated.  Traditionally, parsimony methods have been favoured but recent studies have shown that these approaches are not as accurate as the Bayesian implementation of the Mk model.  Here we expand on these findings in several ways: we assess the impact of tree shape, maximum-likelihood estimation using the Mk model, and analyse both binary and multistate characters.  We find that all methods struggle to correctly resolve deep clades within asymmetric trees, and based on small character matrices.  The Bayesian Mk model is the most accurate method for estimating topology, but with lower precision than other methods.  Equal weights parsimony is more accurate than implied weights parsimony, and maximum likelihood estimation using the Mk model is the least accurate method.  We conclude that the Bayesian implementation of the Mk model should be the default method for phylogenetic estimation from phenotype datasets, and we explore the implications of our simulations in reanalysing several empirical morphological character matrices.  A consequence of our finding is that high levels of precision or the ability to classify species or groups with much confidence should not be expected when using small datasets.  It may now be necessary to depart from the traditional parsimony paradigms of constructing cladistic matrices, towards datasets constructed explicitly for Bayesian methods.

Survival of the smallest?  Trends in brachiopod size across the end-Triassic mass extinction

Fiona Pye², Alexander M. Dunhill², Zoe Hughes¹, Chris Hughes¹ and Richard J. Twitchett¹

¹Natural History Museum, London, UK
²University of Leeds, UK

Many taxonomic groups have been shown to physically respond to changes in environment, such as brachiopods that are known to display body size changes in response to climatic events.  Environmental changes just before the Triassic–Jurassic boundary caused a mass extinction, and this study investigated the impact of this event on brachiopod body size.  Using the Natural History Museum, London collections, the study was undertaken at the generic level for groups within the Rhynchonellida.  The three principal axes were measured on specimens that, where possible, were recorded to ammonite zone stratigraphic resolution.  Body volume was calculated using the Novack-Gottshall (2008) method.  These data were used to investigate the significance of any changes in mean size and to undertake a time series analysis.  Only two of the genera measured are recorded in both the Triassic and Jurassic, i.e. Rhynchonella and Calcirhynchia.  There is a significant drop in body volume between the Rhaetian and the Hettangian, with many genera being smaller in the early Jurassic.  The next step in the study is to consider the effect of facies differences in specimens from varying localities, and to increase sample sizes.

Evaluating bite marks and predation of fossil jawless fish during the rise of jawed vertebrates

*Emma Randle and Robert Sansom

University of Manchester, UK

Vertebrate assemblages were generally dominated by jawless fish (ostracoderms) during the Silurian, but towards the end of the Devonian, jawed vertebrates dominated.  Theories accounting for this faunal shift range from predation or competitive displacement by jawed vertebrates to limited dispersal capabilities of ostracoderms resulting in elevated sensitivity to large-scale climatic fluctuations.  Differences in feeding ecologies between ostracoderms and jawed vertebrates (generally interpreted as filter feeders and predators respectively) rule out competitive displacement.  Here we present direct evidence for the predation of heterostracan ostracoderms from the fossil record.  We found puncture marks on more than 25 heterostracan specimens that are consistent with interpretation as bite marks; for example, the marks exhibit: regular geometric shape; complementary traces on both sides of the animal; a distinct pattern; and evidence of sublethal (repair) attacks.  Occurrences of these attacks dramatically rise during the Emsian, which coincides with an increase in gnathostome diversity.  We use the distribution of jawed vertebrates and occurrences of heterostracan bite marks though space and time to test hypotheses relating to increasing predation, possible faunal interactions, and the evolutionary history of vertebrates.

The new rudist phylogeny (Bivalvia, Hippuritida)

Valentin Rineau and Loïc Villier

CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France

Rudists (order Hippuritida) are heterodonts bivalves close to the Megalodontidae.  They appeared in the Upper Jurassic and spread all around the Tethys in warm shallow seas, only to become completely eradicated at the Cretaceous–Palaeogene boundary.  This group developed completely original morphologies, probably due to a shell uncoiling, which make them recognizable at first glance.  A strong development of the myocardinal apparatus, the loss of a ligament and the presence of canals in the shell are some examples of morphological events which occur in rudists.  Here we present a new phylogeny based on representatives of each family – from Diceratidae to Hippuritidae – to resolve the early nodes of the rudist phylogeny.  We point out the weaknesses of the unique previous phylogeny, on the formalization of homology hypotheses, and we propose a completely new set of morphological descriptors, and therefore characters, based on comparative anatomy with a decomposition of traditional ‘morphological wholes’ (e.g. hinge) into independent characters (e.g. anterior tooth, central tooth socket).  We show that the previous unique character ‘pallial canals’ can be decomposed to point to four different origins.  The results are presented in three-taxon analysis, a cladistic method that uses a new formalization of homologies directly in trees, and without matrix.

Discriminating between melanosomes from different tissues using geometry and trace element chemistry: a tool for interpreting fossil vertebrate soft tissues

*Valentina Rossi and Maria E. McNamara

University College Cork, Ireland

Melanosomes are important components of integumentary tissues in modern vertebrates and have been reported from various vertebrate and invertebrate fossils ranging in age from the upper Palaeozoic to the Cenozoic.  Much previous work on fossil melanin has focused on reconstructions of integumentary colour in fossils.  Modern vertebrates, however, also possess melanin in internal tissues; the impact of these internal melanosomes on interpretation of fossil soft tissues – and fossil colour – has not been assessed.  Here we present the first systematic analysis of the anatomical distribution and abundance of melanosomes in different vertebrate taxa.  The abundance of melanin in tissues of extant amphibians, reptiles, birds and mammals was assessed using histological sections.  Melanin extracts from these tissues were analysed using scanning electron microscopy and synchrotron X-ray fluorescence.  Our results reveal that melanosomes are abundant in internal organs of extant vertebrates.  These internal melanosomes always differ in trace element chemistry, and, in some taxa, in geometry, to melanosomes from the skin.  These findings can be applied to fossils to allow integumentary and non-integumentary melanosomes to be discriminated, thus allowing more accurate interpretations of internal anatomy and integumentary colour in fossils.

Primitive contour feathers in paravian dinosaurs and the evolution of avian plumage

*Evan Saitta and Jakob Vinther

University of Bristol, UK

Identifying fossil feather morphology is challenging.  Here, comparisons between phylogenetically distant dinosaur taxa allow for better understanding of feather morphology and insight into their function and evolution.  An Anchiornis specimen possesses disarticulated contour feathers revealing a novel feather type – a ‘shaggy’, open-vaned, bifurcated feather with long barbs attached to a short rachis.  Comparisons between Psittacosaurus, Sinosauropteryx and Anchiornis suggest a range of plausible contour feather morphologies for Sinosauropteryx with a ‘tuft’ morphology of multiple barbs connected basally but lacking a rachis tentatively preferred.  Comparison with Confuciusornis supports Anchiornis flight feathers being at least partially open-vaned.  Open-vaned contour and flight feathers in Anchiornis suggest that differentiated barbicels may be relatively derived characters.  ‘Shaggy’ contour feathers would have influenced Anchiornis thermoregulatory and water repellence abilities, and along with open-vaned flight feathers, would have decreased aerodynamic efficiency.  Simplified, open-vaned Caudipteryx forelimb feathers support secondary flightlessness and imply that other potentially secondarily flightless theropods, like large dromaeosaurs, had simplified feathers and were ‘shaggy’ in appearance.  The results have implications for many non-avian dinosaur depictions and the function and evolution of feathers.

Testing adaptive radiation scenarios in marine fishes by combining phylogenomic and paleobiological data

Francesco Santini

Associazione Italiana Studio Biodiversita, Italy

Adaptive radiation scenarios have been invoked to explain the diversity of some of the best studied groups of organisms (e.g. rift lake cichlids, Hawaiian silversword alliance, passerine birds).  Under the most traditional adaptive radiation model, numerous lineages start diverging within a brief period of time from an ancestral adaptive type, with each new lineage filling an available ecological niche; subsequently this rapid initial morphological evolution is replaced by relative stasis due to most available niches having already been filled.  A number of recent studies, based on molecular phylogenies, questioned the generality of this model and found little evidence of an early burst of morphological diversification in most studies.  For most of these clades, however, it is not known if inclusion of the palaeodiversity would have modified the results.  I will compare the results of our study of several major groups of marine teleosts, such as tetraodontiforms (puffers, triggerfishes and allies), acanthuroids (surgeonfishes, luvar) and sparoids (seabreams, emperors and allies).  All of these groups possess a rich fossil record, which to date has rarely been used in evolutionary studies.  I will show how the results based on extant taxa and those based on extant plus extinct species differ, and how inclusion of fossil data can alter the conclusion of studies based on molecular phylogenies.

Take the fish taxi!  Phylogeny and palaeobiogeography of the Margaritiferidae

Simon Schneider¹, Rafael Araujo², Dirk Erpenbeck³, Annie Machordom² and Kevin J. Roe⁴

¹CASP, UK
²Museo Nacional de Ciencias Naturales-CSIC, Spain
³LMU Munich, Germany
⁴Iowa State University, USA

Today, eleven species of Margaritiferidae occur scattered over Eurasia, North America and northern Africa.  Margaritiferidae likely originate from the extinct Silesunionidae.  Although identification of fossil remains is problematic, numerous Mesozoic and Cenozoic fossils can be assigned with some confidence to the Margaritiferidae.  Results of molecular phylogenetic analysis of all extant species, based on two mitochondrial and three nuclear markers, were processed with BEAST to infer divergence times.  Assuming mean substitution rates, the Margaritiferidae are calculated to have originated in the Miocene.  Using fossils for calibration, the results indicate substitution rates ten times lower than usual and four levels of intercontinental relationships.  This is difficult to explain as Margaritiferidae occur exclusively in fresh water; their parasitic larvae usually attach to the gills of amphidromous host fish and thus it is unlikely that land bridges promote propagation.  It is further unlikely that mussel larvae survive travel in saline waters.  We propose that Margaritiferidae spread during phases of high freshwater runoff or seasonal freshwater layering.  This model has broader implications for the phylogeography of the Unionida, which all depend on the ‘fish taxi’ for propagation.

Are rudist bivalves cockles?  How Pachyrisma grande Morris and Lycett, 1850 may jumble Mesozoic bivalve phylogeny

Simon Schneider

CASP, UK

Pachyrisma grande and the family Pachyrismatidae are considered the most likely ancestors of the Hippuritida.  The Hippuritida (vulgo ‘rudists’) are one of the most diverse bivalve groups of the Mesozoic with approximately 200 genera and 2,000 species.  The origins of Pachyrisma are considered to lie in the Megalodontidae, a group of large-sized Triassic lagoonal bivalves, predominantly occurring in the Tethyan realm.  Re-study of Pachyrisma grande has revealed several characters that were previously unknown or misinterpreted.  These include the presence of radial external ornament on the posterior slope, a posterior lateral tooth PI, a pitted pallial line, the absence of a lunule and the shape and position of the nymph.  These features support Pachyrisma as the closest known ancestor of the Hippuritida, but not as a descendent of the Megalodontidae.  The cardioid hinge and the lack of a lunule suggest an origin close to Protocardia in the Cardioidea.  The proposed evolutionary relationships have several broader implications for bivalve systematics.  Megalodontidae probably went extinct at the Triassic–Jurassic boundary, early cardioid evolution requires revision, Hippuritida are probably descended from Cardioidea via the Pachyrismatidae, and Cardioidea are thus paraphyletic with regard to Hippuritida.

An unexpected gastropod: a possible representative of the predominantly Mesozoic family Spinilomatidae (Mollusca: Caenogastropoda) found in the Middle Danian (Early Paleocene) coralline limestone of Faxe Quarry, Denmark

K. Ingemann Schnetler¹ and Jesper Milàn^2,3

¹Independent
²Geomuseum Faxe, Denmark
³Natural History Museum of Denmark, Denmark

The coralline limestone of the Middle Danian (Early Paleocene) Faxe Formation of Faxe Quarry, Denmark has yielded a very diverse mollusc fauna, with more than 220 described species of gastropods alone.  A new specimen is identified as a possible representative of the family Spinilomatidae.  The specimen is preserved as an impression in the consolidated limestone.  By making a silicone mould of the impression, a high-quality cast of the specimen was retrieved, enabling identification.  Previously, the family Spinilomatidae was known only from the Mesozoic of Europe and India and from the Late Paleocene of California.  This extends the biogeographical range of the subfamily to Europe and highlights the status of Faxe Quarry as an important fossil locality.

What are ‘opossum-like’ fossils?  New phylogenetic hypothesis based on CT-scanning and new features on petrosal anatomy

Charlène Selva and Sandrine Ladeveze

CNRS UMR 7207, Muséum National d’Histoire Naturelle and Sorbonne Universités, France

Herpetotheriids are considered a key taxon in the evolutionary history of Marsupialiformes and particularly in the origin of opossums.  Herpetotheriids include fossil marsupialiformes whose dentition is said to be ‘opossum-like’.  However, the concept of ‘opossum-like’ falsely combines herpetotheriids and peradectids, with no phylogenetic basis.  Rather, this concept is based on the general, and largely plesiomorphic, morphological resemblance of herpetotheriids to extant opossums.  New data on internal aspects of the skull of herpetotheriids revealed by X-ray microtomography (CT-scanning) allow a better understanding of the phylogenetic affinities of ‘opossum-like’ marsupialiformes.  The present study describes and compares 3D models of the petrosal bone of Peratherium elegans, Peratherium cuvieri and Amphiperatherium minutum.  A cladistic analysis of osteological characters (including the ear region) in 23 extant and fossil metatherians (including the four herpetotheriids of this study) confirms the highly informative nature of this bone for phylogenetic reconstructions.  The results indicate that P. cuvieri, P. elegans and A. minutum form a monophyletic group, but the other herpetotheriid of the analysis, Herpetotherium cf. fugax, is not part of this clade.  This casts into doubt the monophyly of herpetotherids and the relationships of peradectids and herpetotheriids with the crown clade Marsupialia.

Paracestracion danieli sp. nov., a new species of bullhead shark from Eichstätt, Germany (Chondrichthyes: Heterodontiformes)

*Tiffany Slater¹, Kate Ashbrook¹ and Jürgen Kriwet²

¹University of Worcester, UK
²University of Vienna, Austria

A new species of bullhead shark (Chondrichthyes: Heterodontiformes) is reported from the Kimmeridgian of Eichstätt, Germany.  This subadult specimen is compared to the holotype Paracestracion falcifer (AS-VI-505) and to the related extant juveniles Heterodontus japonicus, Heterodontus zebra, Heterodontus philippi and two adult Heterodontus japonicus.  Paracestracion danieli sp. nov. differs in its tooth morphology, number of tooth families, and position of the anterior fin spine, coracoid and puboischiadic bar.  Additionally, seven distance measurements are used to investigate differences in body shape throughout ontogeny and between species.  Measurements include total body length, length of coracoid and puboischiadic bar and the distance between each of the first and second dorsal fins, the second dorsal fin and caudal fin, the pectoral and pelvic fins, and the pelvic fins and anal fin.  Principal components analysis of these data reveals a strong divergence between Paracestracion danieli sp. nov., Paracestracion falcifer and Heterodontus; most of the variation relates to the distance between the pectoral and pelvic fins and the distance between the posterior dorsal and caudal fins (PC1=78.9%; PC2=15.9%).  This investigation reveals a greater species diversity of the extinct genus Paracestracion than previously thought.

Phanerozoic survivors: actinopterygian evolution through the Permo–Triassic and Triassic–Jurassic extinction events

*Fiann Smithwick

University of Bristol, UK

Actinopterygians (ray-finned fishes) successfully passed through four of the big five mass extinction events of the Phanerozoic, but the effects of most of these extinction events on the group are poorly understood.  It has so far been assumed that the Permo–Triassic mass extinction (PTME) and end-Triassic extinction (ETE) had little impact on actinopterygians, despite devastating many other vertebrate groups.  Here, we test this assumption using two independent morphometric techniques, geometric and functional, plus diversity estimates, to assess the effects of these two extinction events on the group.  The PTME sees small but insignificant changes in both disparity measures while diversity actually increases.  Relatively low levels of disparity in the Early Triassic are followed by increases from the Middle to Late Triassic, with a particular expansion of functionspace coinciding with the radiation of neopterygians and the evolution of novel feeding adaptations.  Through the ETE, a drop in diversity occurs alongside small shifts in geometric and functional disparity, followed by expansions into novel areas of ecospace.  Little evidence is observed for major perturbations in actinopterygian evolution through either extinction event, suggesting that the PTME and ETE did not have the severe negative impacts on the group observed for other major clades.

Exceptional preservation of the basal body of conodont elements from the Dienerian (Early Triassic) of Oman: implications for systematics and functional morphology

Louise Souquet and Nicolas Goudemand

CNRS UMR 5242, Université de Lyon and Ecole Normale Supérieure de Lyon, France

Conodonts are extinct marine jawless vertebrates, most recently assigned to stem cyclostomes based on phylogenetic analyses.  This interpretation is supported by a functional model that suggests that conodonts fed using a pulley-like mechanism, similar to crown cyclostomes (Goudemand et al. 2011).  The feeding apparatus of conodonts usually consists of 15 teeth-like elements constructed from two tissues: an enamel-like crown and a dentine-like basal body.  The basal body tissues are rarely preserved, and has never been reported from grasping S and M elements of Triassic conodonts.  Goudemand et al.’s functional model (2011) was based on Early Triassic conodonts and assumed that the basal body did not hinder the movement of the element around a presumed ‘lingual cartilage’.  Here we report for the first time elements of neospathodid conodonts from Dienerian rocks of Oman where the basal body is partly preserved.  Specimens recovered to date support the functional model.  As new material is recovered, we hope to find more such specimens to assess these observations.

Photogrammetry: preserving for future generations an important fossil site in Maine‑et‑Loire (France)

*Alan R.T. Spencer¹ and Christine Strullu-Derrien²

¹Imperial College London, London, UK
²Natural History Museum, London, UK

‘La Tranchée des Malécots’ is a disused road-stone quarry in the south of the Armorican Massif in Chaudefonds-sur-Layon (Maine et Loire, France).  This important site is situated next to abandoned Carboniferous coal mines of the same name and provides a unique window into the Namurian (326.4–315 Ma) flora of the region.  The geology of the site was first recorded by Carpentier in 1932 and is attributed to the ‘Sillon houiller de la Basse-Loire’ structural unit.  The site consists of bedded ‘pierres carrées’ (= square stones) volcaniclastic ash deposits interspersed with layers rich in plant remains.  These rocks are heavily jointed and thus prone to freeze-thaw weathering.  The palaeoflora is dominated by large (1–9 m) lycoposid trunks and branches (Lepidodendron; Lepidodendropsis), in situ rhizomes (Stigmaria), leaves (Lepidophylloides), and numerous unidentified plant remains.  Fossils are preserved as carbonized compressions or as three-dimensional moulds.  In the 80 years since the discovery of the site, weathering and vegetational growth have taken their toll on the sections.  Here we present the results of preliminary attempts to conserve the remaining fossils for future generations using photogrammetry: a digital technique that produces realistic three-dimensional models using minimum equipment and with little overall cost.

Trophic dynamics in the Burgess Shale: re-evaluating the community ecology of the Greater Phyllopod Bed through biovolumetrics and taphonomy

*Richard Stockey¹ and Martin R. Smith²

¹Stanford University, USA
²Durham University, UK

Our understanding of Cambrian ecology stems primarily from exceptionally preserved deposits such as the Burgess Shale.  To date, community reconstructions have focused on abundance data to understand the structure of Cambrian ecosystems.  Biomass, however, is increasingly used to quantify ecological dominance within modern environments.  Moreover, the archetypal Burgess Shale ‘community’ occurring in the Greater Phyllopod Bed may represent a composite assemblage of transported fauna and organisms living in situ.  Previous community studies therefore provide a potentially biased description of early metazoan ecosystems.  Here we supplement existing population data with new surveys of body size variation and species associations to model the relative ecological roles of taxa from the Greater Phyllopod Bed.  Biomass estimates indicate that scavenging marine worms dominated the burial environment, contradicting previous hypotheses that deposit-feeding arthropods were the ecological nexus.  Our approach further reveals at least two distinct communities preserved in the Greater Phyllopod Bed: an in situ trophic web dominated by the priapulidomorph Ottoia and morphologically similar problematica, plus laterally and vertically transported death assemblages.  We present a new, dynamic model of Burgess Shale palaeoecology, separating components of external food webs from the indigenous scavenging fauna of the low-oxygen burial environment.

Early and middle Cambrian palaeoscolecids (Cycloneuralia) of southern Scandinavia

Michael Streng, Jan Ove R. Ebbestad and Vivianne Berg-Madsen

Uppsala University, Sweden

A previously undocumented diversity of Cambrian palaeoscolecids is presented from localities in Sweden, Norway, and Denmark.  The material includes isolated sclerites as well as the first macroscopic specimens reported from the palaeocontinent Baltica.  The sclerites are all of early middle Cambrian age and have been assigned to at least four new species of Hadimopanella.  The two recovered macroscopic specimens are of late early Cambrian and of early middle Cambrian age, respectively.  The early Cambrian specimen is described as Maotianshania? sp. and represents the first record of the family Maotianshaniidae outside China.  The middle Cambrian specimen is almost complete and represents a new species of Wronascolex.  It is characterised by a previously undocumented distribution of sclerites, which change in size and ornamentation from the anterior to the posterior end of the annulated trunk.  This distribution pattern can explain the high variability of species of the sclerite-based genus Hadimopanella as well as the occurrence of rare morphotypes of Hadimopanella in otherwise rich samples.  Evaluation of the available data on the ontogeny of palaeoscolecids regarding the relationship between body and sclerite size suggests that sclerite size might be species-specific and should be considered when comparing taxa with morphological similar sclerites.

Reconstructed life cycle of a Proterozoic holozoan

Paul K. Strother¹, David Wacey², Martin D. Brasier^3,† and Charles H. Wellman⁴

¹Boston College, USA
²University of Bristol, UK
³University of Oxford, UK
⁴University of Sheffield, UK

Phosphatic nodules from the c. 1 Ga non-marine Torridonian Sequence of northwest Scotland preserve populations of multicellular cell balls (stereoblasts), some of which are surrounded by a distinctive jacket of elongate cells.  These complex multicellular forms co-occur with naked stereoblasts and unicellular, multinucleate cells that form a syncytium (coenobium).  These microfossils are described in a companion poster by Wacey et al.  Exceptional preservation of individual specimens at successive stages of differentiation has enabled us to hypothesize a reconstructed life cycle.  Endoreduplication and karyokinesis in a single cell form a distinctive coenobium.  As the original cell wall degrades, individual nuclei cellularize, forming a naked stereoblast.  Cell differentiation occurs when some of the parenchymatous cells of the stereoblast begin to elongate, forming sausage-shaped cells.  These elongate cells then migrate to the surface, thicken their walls, and form a surficial layer that is one cell in thickness.  Our hypothetical life cycle parallels that seen today in the free-living, saprophytic ichthyosporean, Creolimax fragrantissima, but with the addition of the distinctive outer layer which probably functioned as a cyst wall.  This fossil adds to growing evidence that suggests that multicellularity in metazoans evolved via the co-option of developmental pathways that had evolved previously in ancestral unicellular holozoan protists.

Dentures and a gummy sauropod

Suravech Suteethorn

Mahasarakham University, Thailand

Series of sauropod tooth rows lacking jawbone (dentures) are reported from the Early Cretaceous Sao Khua Formation at the Phu Kum Khao locality in Kalasin Province, Northeastern Thailand.  The set of lower teeth SM K4-346 and -347 is composed of 23 entire teeth and fragments from several others.  Teeth from the extremities of the denture have the smallest size, whereas the largest teeth are in the middle of the row.  The crowns are slightly wider labiolingually at mid-length.  Teeth are separated from each other and show a peculiar twist, as in SM K4-347-8 to -12.  The apex of the eighth tooth shows slight rotation, the ninth and tenth point downwards and the twelfth is completely rotated.  This condition confirms that there was no jawbone.  It is not clear, however, how such an unusual phenomenon like a jawbone-less denture could be preserved.  The discovery of isolated dentures might be linked to the presence of a thick gum which would keep the position of teeth in situ after the body decays.

Alpha diversity and palaeoecology of the Cretaceous in the Alpstein, Switzerland

Amane Tajika and Christian Klug

University of Zurich, Switzerland

The Alpstein massif (northeastern Switzerland) has been of great interest for geologists for several decades because of its excellent outcrops.  Although rich and relatively high diverse associations of fossils have been reported, there has been no comprehensive overview of the macrofossil associations.  Here, we report the fossil assemblages and discuss palaeoecological changes from the Barremian to Cenomanian of the Alpstein.  Examined units include the Tierwis Formation consisting of the Altmann and Drusberg Members (latest Hauterivian–late Barremian), the Schrattenkalk Formation (late Barremian–Aptian), the Garschella Formation (Aptian–earliest Cenomanian) and the Seewen Formation (Cenomanian).  We sampled macrofossils from highly fossiliferous layers of the Tierwis area of the Alpstein and analysed palaeoecological changes using ecospace utilization approaches.  All fossils were classified based on ecological parameters of tiering, motility and feeding mechanism and were subsequently plotted into the three-dimensional ecospace.  The results of the palaeoecological analyses demonstrated dynamic changes in ecospace utilization through time.  Comparison of the results of our palaeoecological analyses and regional sea level fluctuations suggests that the two phenomena are linked.

New microgastropod assemblages from the lower Miocene of the Mesohellenic Basin

*Danae Thivaiou¹, Efterpi Koskeridou¹ and Mathias Harzhauser²

¹National and Kapodistrian University of Athens, Greece
²Natural History Museum Vienna, Austria

The lower Miocene (Aquitanian) microgastropods of Greece are poorly documented.  The present study focuses on well-preserved material from a section in the Mesohellenic Basin in the Grevena area which has not been described previously.  Palaeobiogeographically, the basin belongs to the rather homogeneous Proto-Mediterranean-Atlantic Region (which includes France, the entire Mediterranean, and central Iran).  The Mesohellenic Basin is a piggy-back basin that was active from the end of the Eocene until the Middle Miocene and contains abundant marine fossils.  Previous studies of the Oligocene and lower Miocene focused mostly on larger-sized species.  In the present study, systematic analysis of the fossil content of the section has yielded interesting results that inform the fossil molluscan record of the Hellenic area.  About 60 species of microgastropods were identified, most of which are recorded for the first time from the Lower Miocene of Greece, and including potential new species.  The faunal composition suggests affinities with early Miocene faunas from Italy and Austria, and the ecological characteristics of the fauna indicate a shallow marine oligohaline to euhaline environment.

Body size change of marine benthic macroinvertebrates in response to environmental stressors during the Pliensbachian–Toarcian Extinction Event (Early Jurassic)

*Hannah Tilley¹, Richard J. Twitchett², Jonathan A. Todd² and Silvia Danise^3,4

¹University College London, UK
²Natural History Museum, London, UK
³University of Georgia, USA
⁴Plymouth University, UK

The Pliensbachian–Toarcian (~183 Ma) was an interval of global warming and associated environmental changes which altered terrestrial and marine ecosystems worldwide.  In the aftermath of this hothouse extinction interval, temporary body size decrease (the Lilliput effect) has been documented in some marine benthic macroinvertebrates.  This may have conferred a selective advantage in the presence of shifting environmental factors.  In this study we recorded body size of 39 Pliensbachian–Toarcian marine macroinvertebrate species from the Cleveland Basin, North Yorkshire.  Analyses showed that surficial, filter-feeding functional groups had a greater proportion of surviving taxa in the aftermath of the extinction interval than other functional groups.  Significant decrease in the body size of the common filter-feeder Pseudomytiloides dubius after the extinction interval is consistent with the Lilliput effect.  Each of the measured geochemical proxies of environmental change had a significant relationship with at least one of the species or functional groups.  δ⁹⁸/⁹⁵Mo (‰) showed the greatest number of significant correlations with individual species, whereas δ¹³C_org (‰) displayed more significant correlations with functional groups.  Significant relationships between geochemical proxies and sizes of individual species or functional groups support previous evidence that ecological change was probably driven by environmental shifts during this past warming event.

Palaeoecological reconstruction of the community of the Kalana Lagerstätte

Oive Tinn¹, Leho Ainsaar¹, Philippe Gerrienne², Stefi Guitor¹, Kalle Kirsimäe¹, Viirika Mastik¹ and Tõnu Meidla¹

¹University of Tartu, Estonia
²University of Liège, Belgium

The Kalana Lagerstätte (Aeronian, Silurian) in Central Estonia has revealed a number of exceptionally preserved fossils, both auto- and heterotrophs.  The most abundant fossil group in the Lagerstätte is non-calcified algae; the fauna is diverse and includes benthic, nectonic and planktonic animals.  The excellent preservation of some fossils, notably some specimens of crinoids, suggests that they were buried in situ.  However, shelly fossils, including brachiopods and gastropods, are common in storm-accumulated coquina lenses.  Ten ostracod taxa have been identified to date.  Cuticle remains of the eurypterid Eurypterus tetragonophthalmus, occasional accumulations of shells of leperditiids and rare trilobite remains have been reported.  Tabulate corals, small rugosan corals and conulariids are quite common; less common fossils include bryozoans, sponges, orthoconic and coiled nautiloids, and a single recently discovered agnathan.

Storm deposits as graves for the Fezouata Biota (Lower Ordovician, Morocco)

Romain Vaucher, Bernard Pittet, Hélène Hormière, Emmanuel L. O. Martin and Bertrand Lefebvre

CNRS UMR 5276, Université de Lyon and Ecole Normale Supérieure de Lyon, France

The Great Ordovician Biodiversification Event (GOBE) is one of the most important radiations of the Phanerozoic Eon.  The GOBE is characterised by an exponential diversification of classes within phyla that appeared during the Cambrian.  Palaeontologists have recognized a major gap in the record of soft-bodied faunas spanning the late Cambrian – Middle Ordovician time interval.  The recent discovery of a late Tremadocian Konservat-Lagerstätte in the Fezouata Shale (Anti-Atlas, Morocco) that yielded thousands of exceptionally well-preserved fossils (EPF) is thus of prime importance for understanding the rise of animal life.  In the Zagora area, Lower Ordovician deposits consist in c. 900m of siltstones and sandstones deposited in