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Cartorhynchus, new primitive (basal) ichthyosauriform from Lower Triassic of China

Ben Creisler

A new online paper in Nature:

Ryosuke Motani, Da-Yong Jiang, Guan-Bao Chen, Andrea Tintori, Olivier
Rieppel, Cheng Ji & Jian-Dong Huang (2014)
A basal ichthyosauriform with a short snout from the Lower Triassic of China.
Nature (advance online publication)

The incompleteness of the fossil record obscures the origin of many of
the more derived clades of vertebrates. One such group is the
Ichthyopterygia, a clade of obligatory marine reptiles that appeared
in the Early Triassic epoch, without any known intermediates. Here we
describe a basal ichthyosauriform from the upper Lower Triassic (about
248 million years ago) of China, whose primitive skeleton indicates
possible amphibious habits. It is smaller than ichthyopterygians and
had unusually large flippers that probably allowed limited terrestrial
locomotion. It also retained characteristics of terrestrial diapsid
reptiles, including a short snout and body trunk. Unlike more-derived
ichthyosauriforms, it was probably a suction feeder. The new species
supports the sister-group relationships between ichthyosauriforms and
Hupehsuchia, the two forming the Ichthyosauromorpha. Basal
ichthyosauromorphs are known exclusively from south China, suggesting
that the clade originated in the region, which formed a warm and humid
tropical archipelago in the Early Triassic. The oldest unequivocal
record of a sauropterygian is also from the same stratigraphic unit of
the region.

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