[3] Xinpusaurus is a thalattosaur, a group of triassic marine reptiles with long, paddle-like tails and short legs with independently movable digits.

[1] Xinpusaurus bamaolinensis was described in 2003 from SPCV 30015, a complete skeleton with a well-preserved skull and jaws found in two isolated slabs.

[1] Inconsistencies within its description (such as reporting a quadratojugal, a feature unknown in thalattosaurs) have led to some confusion over its diagnosis, and a redescription would be necessary to resolve these issues and determine if it is a valid species or not.

A 2013 analysis showed that many of the traits initially believed to differentiate X. kohi from X. suni were inaccurate, either due to incomplete data, misidentification, or poor preservation.

This redescription provided additional diagnostic features and argued that the alterations were relatively minimal and that the posterior slab was almost certainly from the same individual as the anterior one.

Below is a cladogram based on that analysis:[4] Petrolacosaurus kansensis Youngina capensis Prolacerta broomi Miodentosaurus brevis Endennasaurus acutirostris Anshunsaurus huangguoshuensis Anshunsaurus wushaensis Askeptosaurus italicus Paralonectes merriami Concavispina biseridens Xinpusaurus suni Clarazia schinzi Hescheleria ruebeli Agkistrognathus campbelli Nectosaurus halius Thalattosaurus alexandrae Thalattosaurus borealis