Unusual tetrapod teeth from the Upper Triassic Chinle Formation, Arizona, USA
Two teeth collected from the Upper Triasssic Chinle Formation of northeastern Arizona are described here and named Kraterokheirodon colberti gen. et sp. nov. These teeth are novel in having an occlusal ridge with six cusps and a posterior shelf lacking dentine. Evidence for thecodont implantation of the root suggests amniote affinities for these teeth. They do not match any teeth known for basal vertebrates or basal tetrapods. Although the teeth display some affinities with "traversodont" cynodonts, there are significant differences that preclude a referral to this group. These teeth most probably represent an unknown tetrapod clade and document the presence of a large amniote previ- ously unknown from Late Triassic terrestrial faunas.