Tuesday, August 28, 2012

New from JVP - A new poposaur and vertebrate fauna from Poland

Li et al presented on this new poposaur at last year's SVP (as I discuss here) but I'm very excited to finally see the paper, giving it a name with a full description and phylogenetic analysis. It was pretty interesting to hear that this specimen was found in marine sediments and that it possesses characters suggesting at least a semi-aquatic way of life. This new species and other like it (i.e. Qianosuchus) may suggest a strange beginning for Poposauroidea.

Chun Li, Xiao-Chun Wu, Li-Jun Zhao, Tamaki Sato & Li-Ting Wang (2012): A new archosaur (Diapsida,
Archosauriformes) from the marine Triassic of China, Journal of Vertebrate Paleontology, 32:5, 1064-1081

A new Middle Triassic archosaur, Diandongosuchus fuyuanensis, gen. et sp. nov., is described on the basis of a skeleton from the Zhuganpo Member (Ladinian) of the Falang Formation, eastern Yunnan Province, China. It is primarily characterized by the nasal process of the premaxilla extending posteriorly well beyond the external naris, the super-sized coracoid foramen laterally bordered by the scapula, the ischium with a strongly expanded medial portion anteroposteriorly longer than the proximodistal height of the bone, and anteriorly notched cervical osteoderms. D. fuyuanensis is a pseudosuchian on the basis of the crocodile-normal tarsal joint and other features, such as the distal end of the ulna in posterolateral view squared off, osteoderms with a distinct anterior process, the presacral vertebrae dorsally covered by more than one osteoderm, dorsal osteoderm alignment dorsal to presacrals 10–24 staggered, the pubis-ischium contact reduced to a thin proximal contact, and the medial contact of the ischia extensive but the dorsal margins separate. It is from a marine deposit but shows few morphological adaptations of the postcranial skeleton for a semiaquatic way of life when compared with Qianosuchus from the Anisian limestone of the same area. A phylogenetic analysis derived from an existing data matrix suggests that the new archosaur occupies the basal-most position in Poposauroidea and further confirms the poposauroid status of Qianosuchus. On the basis of current information, the discovery of Diandongosuchus does not firmly underscore the affinity of the semiterrestrial vertebrate faunas between the eastern and western regions along the northern coastline of the Tethys.
Also from the new JVP is a report on a new, although rather typical, Late Triassic vertebrate fauna, which includes several archosaurs.

Tomasz Sulej, Grzegorz Nied┼║wiedzki & Robert Bronowicz (2012): A new Late Triassic vertebrate fauna
from Poland with turtles, aetosaurs, and coelophysoid dinosaurs, Journal of Vertebrate Paleontology, 32:5, 1033-1041

We report a new site with an occurrence of isolated bones of a Palaeochersis-like turtle in Norian-Rhaetian fluvial sediments from southern Poland. The turtle remains are associated with bones of a medium-sized aetosaur, a coelophysoid dinosaur, and a larger carnivorous archosaur, as well as a hybodontid shark, ganoid and dipnoan fishes, and a large temnospondyl.