The systematic revision of the genus Nothosaurus from the Germanic Triassic (Muschelkalk, lower and middle Keuper) results in the recognition of five valid species. These are N. edingerae, N. giganteus, N. juvenilis, N. marchicus, and the genotypical species, N. mirabilis. The holotype of Conchiosaurus clavatus from the base of the middle Muschelkalk is unequivocal evidence of the synonymy of Conchiosaurus with Nothosaurus. Since Conchiosaurus has priority, it must be declared a nomen oblitum to preserve the genus name Nothosaurus. Intrageneric relationships of the species as reconstructed by cladistic analysis match the stratigraphic distribution of the species. The first occurrence of the genus is Nothosaurus cf. N. marchicus in the early lower Muschelkalk; the latest occurrence is Nothosaurus edingerae from the middle Keuper (Gipskeuper). Paranothosaurus is a junior synonym of Nothosaurus and supports faunal interchange between the Germanic and Alphine Triassic at the time of the Anisian-Ladinian boundary.