New Yunguisaurus (pistosaurid) specimen from Triassic of China

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com


A new online paper:


Tamaki Sato, Li-Jun Zhao, Xiao-Chun Wu &, Chun Li (2013)
A new specimen of the Triassic pistosauroid Yunguisaurus, with
implications for the origin of Plesiosauria (Reptilia, Sauropterygia).
Palaeontology (advance online publication)
DOI: 10.1111/pala.12048
http://onlinelibrary.wiley.com/doi/10.1111/pala.12048/abstract

An adult skeleton of the pistosauroid sauropterygian Yunguisaurus liae
reveals a number of morphological features not observed in the
holotype, such as the complete morphology of the skull roof, stapes,
atlas and axis, ventral view of the postcranium, and nearly complete
limbs and tail. Size and morphological differences between the two
specimens are mostly regarded as ontogenetic variation, and newly
added data did not affect the phylogenetic relationships with other
pistosauroids significantly. The number of mesopodia (11 carpals and 8
tarsals) exceeds that known in any other Triassic marine reptiles and
does not serve as a precursor of the plesiosaurian pattern with fewer
mesopodia of different topology; it demonstrates variability of the
limb morphology among the Triassic pistosauroids. The pectoral girdles
of Corosaurus, Augustasaurus and Yunguisaurus may indicate early
stages of the adaptation towards the plesiosaurian style of paraxial
limb movements with ventroposterior power stroke.