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Diandongosuchus, new archosaur from Triassic of China



From: Ben Creisler
bcreisler@gmail.com

In the new JVP:


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
DOI:10.1080/02724634.2012.694383
http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.694383



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.