Qianxisaurus chajiangensis (Cheng et al. 2012) Middle Triassic sauropterygian, based on a virtually complete articulated skeleton (manus digits poorly ossified).
Cheng et al. 2012 nested Qianxisaurus as derived from a sister to Wumengosaurus, a taxon that nested closer to thalattosaurs, ichthyosaurs and mesosaurs in the large reptile tree. The Cheng et al. (2012) study had some odd nestings including Kuehneosauridae (rib gliders) a little too close to turtles and thalattosaurs. The large reptile tree widely separated these taxa, as befitting their utterly distinct morphologies.
The large reptile tree nested Qianxisaurus between Pachypleurosaurus, Cartorhynchus and Lariosaurus. Pistosaurus nest as an outgroup in the Cheng et al. (2012) tree, but nest as a sister to Simosaurus in the large reptile tree, a major difference.
The upper temporal fenestrae were small, smaller than in Pachypleurosaurus. The retroarticular process was smaller than in related taxa. The teeth of Qixiansaurus are unusual with a slightly constricted peduncle and short conical crowns.
Despite the small size of the ilium at least four sacrals were present. The strap-like scapula was fused to the anterior coracoid. Large clavicles and osterior coracoids anchored the scapula. The clavicles were broader laterally.
The complete reptile family tree is here.