Latest Literature

A few new papers which recently came to my attention and that deal (at least somewhat) with Triassic vertebrates....


Allain, R., and E. Lang. In Press. Origine et evolution des saurischiens (Saurischian origins and evolution). Compte Rendus Palevol. doi:10.1016/j.crpv.2008.09.013

Abstract: We propose here a short synthesis of the saurischian evolutionary history. Our knowledge of the diversity and evolution of the saurischian non-avian dinosaurs has increased during the past decade. The generalized use of cladistics has led to various phylogenetic hypotheses, some of them in agreement on the evolution of saurischians, even if some controversy remains. The saurischian evolution is closely linked to two of the five great mass extinctions, which punctuated life history, but probably also to a third, less important, extinction event at the end of the Early Jurassic.

Dyke, G. J., McGowan, A.J., Nudds, R.L., and D. Smith. In Press. The shape of pterosaur evolution: evidence from the fossil record. Journal of Evolutionary Biology. doi:10.1111/j.1420-9101.2008.01682.x

Abstract: Although pterosaurs are a well-known lineage of Mesozoic flying reptiles, their fossil record and evolutionary dynamics have never been adequately quantified. On the basis of a comprehensive data set of fossil occurrences correlated with taxon-specific limb measurements, we show that the geological ages of pterosaur specimens closely approximate hypothesized patterns of phylogenetic divergence. Although the fossil record has expanded greatly in recent years, collectorship still approximates a sigmoid curve over time as many more specimens (and thus taxa) still remain undiscovered, yet our data suggest that the pterosaur fossil record is unbiased by sites of exceptional preservation (lagerstatte). This is because as new species are discovered the number of known formations and sites yielding pterosaur fossils has also increased – this would not be expected if the bulk of the record came from just a few exceptional faunas. Pterosaur morphological diversification is, however, strongly age biased: rarefaction analysis shows that peaks of diversity occur in the Late Jurassic and Early Cretaceous correlated with periods of increased limb disparity. In this respect, pterosaurs appear unique amongst flying vertebrates in that their disparity seems to have peaked relatively late in clade history. Comparative analyses also show that there is little evidence that the evolutionary diversification of pterosaurs was in any way constrained by the appearance and radiation of birds.

Reichel, M., Schultz, C.L., and M.B. Soares. 2009. A new traversodontid cynodont (Therapsida, Eucynodontia) from the Middle Triassic Santa Maria Formation of Rio Grande Do Sul, Brazil. Palaeontology 52:229-250. doi: 10.1111/j.1475-4983.2008.00824.x

Abstract: Remains of a peculiar traversodontid cynodont, Protuberum cabralensis gen. et sp. nov., are described herein. The material was collected from two outcrops representing the Therapsid Cenozone (Middle Triassic) of the Santa Maria Formation, and consists of a cranium with most of its dentition preserved and an associated postcranial skeleton. The upper postcanines have two sharp cusps that are connected by a medial crest on unworn postcanines. The specimens possess several autapomorphies, including: (1) presence of thickened bone on the dorsal surface of the skull; (2) thick dorsal ribs, with remarkable processes situated on their dorsal borders that decrease in size distally; and (3) an iliac blade with a series of rugosities along its dorsal border. The lumbar ribs bear overlapping costal plates and have distally projecting rib shafts that differ from the pattern observed in Thrinaxodon, Pascualgnathus and Cynognathus.