silvestrosaurus is an extinct aquatic genus of lariosaurine nothosaurid sauropterygian known from the middle triassic (anisian-ladinian boundary) of monte san giorgio, southern switzerland. it contains a single species, silvestrosaurus buzzii, originally considered to be a species of the closely related "lariosaurus". the species was named by tschanz in 1989, based solely on the holotype pimuz t/2804 comprising the skull, the lower jaw, and a dis-articulated partial postcranial skeleton. "cyamodus hildegardis" tooth bearing elements were found in the stomach region of the specimen. the holotype was collected at punkt 902 of monte san giorgio, from layer 97 of the grenzbitumen zone, dating to the anisian-ladinian boundary of the middle triassic. kuhn-schnyner (1990) reassigned the species to its own genus, creating the combination "s. buzzii". the generic name honors a church near the collection locality of the holotype, dedicated to saint sylvester, a pope during the reign of constantine the great, and from greek "saurus", meaning "lizard", a common suffix for genus names of extinct reptile.