A new species of the Late Triassic rhynchosaur Hyperodapedon from the Santa Maria Formation of south Brazil

A new rhynchosaur, Hyperodapedon huenei sp. nov., is described from the Upp er Triassic Santa Maria Formation of the Parana Basin, Brazil. The holotype is an almost complete skull and mandible, collected at Inhamanda, in the s tate of Rio Grande do Sul, Brazil. The diagnosis of the genus Hyperodapedon Huxley is revised to include not only H. huxleyi Lydekker and H. gordoni H uxley las generally accepted), but also the new species described here, var ious specimens usually assigned to 'Scaphonyx fischeri' Woodward, and 'S'. sanjunensis Sill. H. huenei sp. nov. exhibits a number of plesiomorphic fea tures and appears to be the least derived species of Hyperodapedon, forming a sister taxon to the remaining members of the genus. A preliminary phylog enetic analysis for the more derived rhynchosaurs is presented. 'Scaphonyx' sulcognathus Azevedo and Schultz represents the sister taxon of Hyperodape don, while 'Rhynchosaurus' spenceri Benton is considered to be a more deriv ed Middle Triassic rhynchosaur.