New Species of Thalattosaur Discovered

Chinese paleontologists led by Dr Tao He from the Zhejiang Museum of Natural History in Hangzhou have identified a new species of thalattosaur from a fossil found in the Xiaowa Formation of Guanling, China.

Reconstruction of a thalattosaur (Nobu Tamura / CC BY 3.0)

Reconstruction of a thalattosaur (Nobu Tamura / CC BY 3.0)

Thalattosaurs (meaning ‘ocean lizards’) were a group of prehistoric marine reptiles that lived during the mid and late Triassic period in North America and Eurasia. They resembled large, up to 13 feet (4 m) in length, aquatic lizards, with long, flexible bodies and short limbs.

Dr He’s team has described a new species of thalattosaur, named Concavispina biseridens, in the latest issue of the Journal of Paleontology.

C. biseridens is a nearly complete skeleton with the tip of the rostrum missing, and it is the largest known thalattosaur in terms of absolute skull length. The skull is 50 cm long and the distance from the broken tip of rostrum to the anterior margin of the orbit is 252 mm,” the team wrote.

C. biseridens is characterized by a long skull, measuring approximately half the length of presacral portion of the vertebral column, two rows of blunt teeth on the anterior part of the maxilla, and neural spines that have convex anterior or posterior margins and V-shaped notches in their dorsal margins.

Concavispina differs from all thalattosaurs except Xinpusaurus in that the anterior end of the maxilla is curved dorsally, less than five cervical vertebrae are present, and the proximal end of the humerus is wider than the distal end.

Concavispina biseridens (Jun Liu)

Concavispina biseridens (Jun Liu)

“Thalattosaurs have moderate adaptations to marine lifestyles, including long, paddle-like tails and slender bodies. C. biseridens has a very short neck as ichthyosaurs, but it has a long tail with a laterally compressed appearance due to the presence of relatively high neural spines and long chevrons.”

“The anterior teeth in Xinpusaurus are pointed and robust, while the posterior teeth are blunt and broad. In Concavispina the premaxillary teeth are pointed and slender, while the maxillary teeth are small, blunt, and anteriorly positioned. Xinpusaurus probably had the power to crush shells, while Concavispina could have eaten softer food such as fish and jellyfish,” said study first author Dr Jun Liu from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.

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Bibliographic information: Jun Liu et al. 2013. Osteology of Concavispina biseridens (Reptilia, Thalattosauria) from the Xiaowa Formation (Carnian), Guanling, Guizhou, China. Journal of Paleontology 87 (2): 341-350