The naming of these first specimens was disputed , however . Leopold Fitzinger named the animal Batrachosaurus in 1837 . In 1841 , English palaeontologist Richard Owen referred to the genus as Labyrinthodon to describe its highly folded or labyrinthine teeth . Owen thought the name Mastodonsaurus " ought not to be retained , because it recalls unavoidably the idea of the mammalian genus Mastodon , or else a mammilloid form of the tooth ... and because the second element of the word , saurus , indicates a false affinity , the remains belonging , not to the Saurian , but to the Batrachian order of Reptiles . " Owen recognized the animal was not a " saurian " reptile , yet he also referred Jaeger 's Phytosaurus to the genus . Although the two genera both have similarly sized conical teeth , Phytosaurus was later found to be a crocodile @-@ like reptile . Additional material , including skulls , firmly placed Labyrinthodon as an amphibian . Jaeger also named Salamandroides giganteus in 1828 , basing it on partial occiput , or back portion of the skull . In 1833 , he described a complete skull of S. giganteus that had the same teeth as his Mastodonsaurus , making it the first known complete skull of a temnospondyl . Because Mastodonsaurus was named first , it has precedence over the other names as a senior subjective synonym . Batrachosaurus is still used as the name of an unrelated brachyopid temnospondyl .