September 30, 2016:

From text:

Thalattosauria is a clade of marine reptiles exclusively known from the Triassic (Nicholls, 1999 Nicholls, E. L. 1999). It remained poorly understood until the end of the 20th century, because the only records then known were from North America and Europe. In recent years, abundant, well-preserved thalattosaur material has been excavated in sediments of Middle to Upper Triassic age of southwestern China.

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All specimens of Xinpusaurus previously known were collected in the Carnian (Upper Triassic) deposits of Guanling County, Guizhou Province. Here, we report a new specimen from the Ladinian (Middle Triassic) of Xingyi City, Guizhou Province, collected during the 2011 excavation season by a collaborative team of the Geological Museum of Peking University, University of California Davis, University of Milan, and the Field Museum of Natural History (Chicago). It can be referred to the genus Xinpusaurus, but it differs in its anatomy from the other species in the genus. This is the first record of the genus Xinpusaurus in the Middle Triassic. In the following, we provide a detailed description of the morphology of this new species and present a phylogenetic analysis of Thalattosauria to test its relationships within this clade.

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The specimen is nearly complete except for the tail (Fig. 1), with a preserved length of 2.1 m. Including the estimated length of the missing distal part of the tail, the complete skeleton may have exceeded 3 m in length. The length of the skull may be estimated to exceed 42 cm, as indicated by the length of the mandible. This specimen is larger than any other known specimen of Xinpusaurus, in which the total body length is ≤ 2.38 m long, with a skull that is at most 34 cm in length (Yin et al., 2000 Yin, G.-Z., X.-G. Zhou, Z.-T. Cao, Y. -Y. Yu, and Y.-M. Luo. 2000. A preliminary study on the early Late Triassic marine reptiles from Guanling, Guizhou, China. Geology Geochemistry 28:1–23.

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The present report of X. xingyiensis, sp. nov., from the Ladinian Xingyi Fauna expands the distribution range of the genus both temporally and geographically, reconfirming the similarity between the Upper Assemblage of the Xingyi Fauna and the Guanling Fauna.