Abstract
The first thalattosaur from the marine Middle Triassic of Guizhou Province, southern China, is described, and its phylogenetic relationships analyzed. The taxon, Anshunsaurus huangguoshuensis, was found to be the sister-taxon of Askeptosaurus italicus from the southern Alpine Triassic. The paleobiogeography of thalattosaurs, now known from the Middle and Late Triassic of China, Europe, and North America, is discussed.