 At total of three species has been identified with certainty in Chilean formations, "T. carolomartini", "T. natans", "T. antiquus" while the presence of "T. yaucensis" is judged likely.In 1995, the genus "Thalassocnus" was formally described with the species "T. natans", with a partial skeleton, MUSM 433, by paleontologists Christian de Muizon and H. Gregory McDonald."T.