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Diandongosaurus (Sauropterygia) from Triassic of China restudied
From: Ben Creisler
A new online paper:
Tamaki Sato, Yen-Nien Cheng, Xiao-Chun Wu and Hsi-Yin Shan (2013)
Diandongosaurus acutidentatus Shang, Wu & Li, 2011 (Diapsida:
Sauropterygia) and the relationships of Chinese eosauropterygians.
Geological Magazine (advance online publication)
Diandongosaurus acutidentatus Shang, Wu & Li, 2011 is restudied on the
basis of a new specimen. The new specimen provides further information
on the palate of the skull, the shoulder girdle, the gastralia and
hind limbs, and permits revision of the diagnosis. Newly added or
modified diagnostic characters include the presence of a few small
vomerine teeth, the presence of an ectopterygoid, lateral elements of
gastralia distally swollen and curving dorsally, boomerang-shaped
interclavicle and clavicle with a distinct anterolateral process.
Slight variations in the vertebral counts, girdle morphology, and
phalangeal formulae are attributed to the intraspecific variations. A
revised phylogenetic analysis demonstrates that Diandongosaurus is
closely related to the Nothosauroidea and that certain Chinese taxa
(e.g. Keichousaurus) previously affiliated with the
Pachypleurosauridae are more closely related to the Nothosauroidea.
The effect of inclusion or exclusion of fragmentary taxa in the
phylogenetic analysis is observed in the branching pattern of the
cladogram, but it has little effect on the morphological
characterization of the major clades.