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Silurian encrinurid trilobites from Gotland and Dalarna, Sweden
Trilobites of the family Encrinuridae are described from the Silurian of Gotland and Dalarna, Sweden. Twelve species (nine named, of which four are new) are assigned to two genera. Three subgenera of Encrinurus are recognized, including E. (Australurus) subgen. nov. and E. {Nucleurus) subgen. nov. Balizoma is redefined by excluding species here included in E. (Nucleurus). A directional, morphological trend is shown between several populations of E. (Encrinurus) macrourus Schmidt, 1859. E. (E.) schmidti Mannil, 1968 is a junior subjective synonym of E. (E.) schisticola Tornquist, 1884.
Contrasting lifestyles in Lower Jurassic crinoids: a comparison of benthic and pseudopelagic Isocrinida
Lower Jurassic pentacrinitids have been regarded either as pseudopelagic in habit, living suspended beneath floating objects such as driftwood, or as strictly benthic, living much like all known representatives of their sister group the Isocrinidae. The taphonomy of Lower Jurassic pentacrinitids differs significantly from that of contemporary isocrinids in their environments of preservation, extent of disarticulation, occurrence in debris accumulations, frequency of association with driftwood, and the size and position of the driftwood relative to the crinoids.
The size-frequency distribution in palaeoecology: effects of taphonomic processes during formation of molluscan death assemblages in Texas bays
Trichoptera pupae are described for the first time in the Indusial Limestone Formation of Saint-Gerand-le-Puy, Allier, France. The caddisfly pupal cases, named Indusia tubulosa, constitute this limestone. The relationships of these pupae to extant families are analysed and they are placed in the Limnephilinae. Fossil preservation and palaeoenvironment are discussed.
Poriferan affinities of Mesozoic stromatoporoids
The finding of calcite and pyrite spicule pseudomorphs of monaxon spicules in six genera of Mesozoic stromatoporoids confirms poriferan affinities for at least some representatives of this group. Previously, the systematic position has been speculated upon solely from the internal organization of the skeleton.
Archosaur predation on an east African Middle Triassic dicynodont
A description is given of two sets of tooth impressions on the shaft of a kannemeyeriid dicynodont femur from the Middle Triassic (Anisian) Manda Formation of the Ruhuhu Valley, Tanzania. A brief analysis of the dentition is attempted and it is concluded that these impressions were probably made by a rauisuchid thecodontian, for which the name Mandaodonites coxi is proposed.
The community structure of the Middle Cambrian Phyllopod Bed (Burgess Shale)
The palaeoecology and taphonomy of the Middle Cambrian Phyllopod Bed fauna (Burgess Shale, British Columbia) is described. Examination of over 30 000 slabs of shale and more than 65 000 specimens, many of them showing soft-bodied preservation, provides estimates of numbers of individuals and biovolumes of approximately 100 genera belonging to twelve major groups. Life habits are diverse with a sessile and vagrant infauna and epifauna, together with a nektobenthos, being recognized; components of a separate pelagic community are also present.
The nematularium of Pseudoclimacograptus scharenbergi (Lapworth) and its secretion
The nematularium of Pseudoclimacograptus scharenbergi (Lapworth) is a three-vaned structure derived from its hollow nema. The apex of the structure is sealed. The vanes are solid, lack a thickened rim, and comprise thin, irregular lamellae that parallel the semicircular vane outline. Each lamella consists of a body of anastomosing fibrils overlain by a dense outer pellicle. Although the thecae have a bandaged cortex, the vanes lack cortical layers. The nematularium is strikingly irregular in shape and lamella geometry compared to P. scharenbergi thecae.
Ellisites, an Upper Ordovician heliolitid coral intermediate between coccoserids and proporids
The Upper Ordovician heliolitid corals Ellisites labechioides gen. et sp. nov. and E. astomata (Flower) combine vesicular skeletal plates with zones of strongly dilated vertical trabeculae. In these characters they provide the first evidence of a phylogenetic link between the Coccoseridicae and Proporicae. They are referred to a new family, the Ellisitidae, and included in the Coccoseridicae, which necessitates taxonomic modification of the latter to include genera with vesicular skeletal plates.