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Scanning and transmission electron microscopy has been employed to describe the ultrastructure of constituents of two kinds of spore masses recovered on bulk maceration of basal Downtonian (Pridoli Silurian) sedimentary rocks from the Welsh Borderland. Spores of Synorisporites downtonensis, occurring tetrads in narrow, elongate masses, possess a thick homogeneous exospore. Adjacent tetrads are linked by sporopollenin bridges. Variation in distal sculpture is discussed in relation to spore ontogeny. Discoidal mass contain Retusotriletes cf.

• Read more about Ultrastructure of Synorisporites downtonensis and Retusotriletes cf. coronadus in spore masses from the Prídolí of the Welsh Borderland

The first prolacertiform from the British Isles is described. The type specimen of Rhumbopholis scutulata, from the Middle Triassic of Warwick, was originally described as a temnospondyl amphibian. The specimen contains bones belonging to a large and a small prolacertiform, both possibly of the same species, as well as scales of a palaeonisciform fish.

• Read more about Rhombopholis, a prolacertiform reptile from the Middle Triassic of England

The Permian Capitan reef was a predominantly heterotrophic ecosystem strongly differentiated into open surface and cryptic communities. Unlike modern phototrophic coralgal reefs, most of the preservabh epibenthos was housed within the cryptos and zonation developed only in the shallow parts of the reef Contrary to established opinion, most sphinctozoan sponges did not grow upright to form a baffling framework but rather were pendent cryptobionts, as were nodular bryozoans and rare solitary rugose coral: and crinoids. Indeed, many members of the cryptos were obligate cryptobionts.

• Read more about New observations on the ecology of the Permian Capitan Reef, Texas and New Mexico

Osmundopsis hillii sp. nov., from Hasty Bank, Yorkshire, is probably the fertile foliage of Cladophlebis harrisii. New material of Osmundopsis sturii from Gristhorpe suggests that it might be the fertile foliage of part of Cladophlebis denticulata. Sterile foliage that was provisionally assigned to O. sturii is probably a large form of Eboracia lobifolia.

• Read more about Two Osmundopsis species and their sterile foliage from the Middle Jurassic of Yorkshire

A paucispiral operculum is described in situ in a specimen of Tychobrahea aerumnans from the Devonian of Bohemia. The small turbiniform gastropod shell appears to be dextrally orthostrophically coiled in similar fashion to most other fossil and extant gastropod shells, but the clockwise-coiling of the exterior surface of the operculum indicates that coiling of the shell is sinistral hyperstrophic. This is the first description of an operculate gastropod with this type of coiling in the fossil record.

• Read more about Sinistral hyperstrophic coiling in a Devonian gastropod from Bohemia with an in situ operculum

The rare phragmocone-bearing coleoids Adygeya adygensis gen. et sp. nov. and Naefia kabanovi sp. nov. are described from the Aptian of the north-western Caucasus (Russia). They are considered to be the earliest known members of the order Spirulida, belonging to two families, Adygeyidae fam. nov. and Groenlandibelidae, respectively.

• Read more about Two early Cretaceous spirulid coleoids of the north-western Caucasus: their shell ultrastructure and evolutionary implications

The Equini tribe with seven genera forms a monophyletic group defined by one synapomorphy: protocone connected to the protoloph. Fourteen species are considered as the terminal taxa: Protohippus (two species), Calippus (two), Pliohippus (one), Hippidion (three), Dinohippus (three), Astrohippus (one) and Equus (two). A cladistic analysis was performed using 20 characters from cranial morphology, upper and lower teeth, and appendicular skeletons. Polarity of characters was based on outgroup criterion using the Hippotheriini tribe.

• Read more about A cladistic analysis of the horses of the tribe Equini

After the formation of the Isthmus of Panama, about 2-5 Ma, a massive interchange between the previously separated mammalian faunas of South and North America took place. Afterwards, during the Late Pleistocene (Lujanian Land Mammal Age)-Holocene transition (less than 10000 years BP), many of the taxa originally present in South America became extinct. Here, we report results of a statistical assessment of the relative importance of factors potentially associated with extinctions.

• Read more about Reassessment of extinction patterns among the late Pleistocene mammals of South America

The Upper Silurian and Lower Devonian beds along the Dnestr River and its tributaries form one of the sections discussed as a possible international Global Stratigraphic Stratotype and Point (GSSP) for the Silurian-Devonian boundary. On the basis of the co-occurrence of a graptolite (Monograptus uniformis angustidens) and a conodont (Icriodus woschmidti) this boundary was drawn at the base of the Tajna Formation. However, chitinozoans from these strata are typical of Pridoli chitinozoan assemblages, and include the index species, Urnochitina urna, and other taxa, e.g.

• Read more about Chitinozoa of the Silurian–Devonian boundary sections in Podolia, Ukraine

A trigonotarbid (Arachnida: Trigonotarbida) from the oldest known terrestrial ecosystem (Silurian, Pridoli Series) of Ludford Lane, Shropshire, UK is described as Eotarbus jerami gen. et sp. nov., and is the earliest known non-scorpion arachnid. This specimen predates Rhyme Chert and Gilboa trigonotarbids which show more plesiomorphic characters, and is similar to some Early Devonian trigonotarbids from Alken an der Mosel and other German localities of similar age. Eotarbus jerami is too poorly preserved to be assigned unequivocally to a family, but most closely resembles the Trigonotarbidae.

• Read more about A trigonotarbid arachnid from the Upper Silurian of Shropshire