A new H yperodapedon ( A rchosauromorpha, R hynchosauria) from the U pper T riassic of I ndia: implications for rhynchosaur phylogeny

A new species of the rhynchosaur genus H yperodapedon , namely H . tikiensis, is described from well‐preserved skeletal elements that were collected from the U pper T riassic T iki F ormation of I ndia. H yperodapedon tikiensis is diagnosed on the basis of several cranial and postcranial features including longer than wide basipterygoid process, crest‐shaped maxillary cross section lateral to the main longitudinal groove, deeply excavated neural arches of mid‐dorsal vertebrae, long scapular blade, a pronounced deltopectoral crest, proximal humeral end much broader than distal end, iliac length greater than iliac height, equal pre‐ and postacetabular iliac lengths and circular femoral cross section. Two distinct morphotypes of the maxillary tooth plates can be discerned, which are attributed to ontogenetic variations. A maximum‐parsimony analysis was carried out to show that the order R hynchosauria is characterized by nine cranial and one postcranial character states. The analysis reveals that O tischalkia elderae is invalid and the basal forms, H owesia and M esosuchus, are closely related. The M id‐ T riassic genus A mmorhynchus is more derived and forms a sister group to the L ate T riassic subfamily H yperodapedontinae. I salorhynchus and T eyumbaita are basal to the pandemic genus H yperodapedon . Twenty‐four characters that are not homoplasious document major patterns of skeletal evolution in rhynchosaurs. From laterally oriented scapula and slender propodials, the postcranial skeleton evolved into a more robust form as is evident from nearly vertical scapula and increase in the robustness of the propodials. Shortening of the femur is noted in the derived L ate T riassic forms as exemplified in H yperodapedon gordoni , H yperodapedon huxleyi and H . tikiensis .