A new specimen of Yunguisaurus (Reptilia; Sauropterygia) from the Ladinian (Middle Triassic) Zhuganpo Member, Falang Formation, Guizhou, China and the restudy of Dingxiaosaurus

Abstract A new articulated juvenile specimen of Yunguisaurus liae (GMPKU-P-1528) from the Ladinian (Middle Triassic) Zhuganpo Member, Falang Formation, Xingyi, Guizhou, China presents new morphological information on the relatively complete atlas and axis. The comparison of the all four Y. liae skeletons with the holotype (DMK 8) of Dingxiaosaurus luyinensis reveals that there is no morphological difference between the two species. The similarities include the similar orientation of the tarsals, the same value of the ratio of the distal width to the proximal width of the tibia and the ratio of the fibula length to the tibia length. The taxonomy of D. luyinensis , however, remains controversial. It cannot be distinguished from other pistosauroid taxa due to the lack of comparative portions of the skeletons preserved (e.g., Chinchenia , Kwangsissaurus ). It may turn out that D. luyinensis and Y. liae stand for the same species when more complete materials become available.