A new species of the rare batomorph genus Hypolophodon (?latest Cretaceous to earliest Paleocene, Argentina)

Abstract

Isolated teeth of a new species of the rare batomorph genus Hypolophodon were found in Paleocene beds of the Lefipan Formation (Maastrichtian-Paleocene) of southern Argentina. The new species H. patagoniensis differs from the type species H. sylvestris in the absence of an occlusal tranverse crest on the crown of unworn teeth and of a broad and rounded central uvula on the lingual face of the crown; and in the presence of a lower boundary of the enameloid smooth on all crown faces, many expanded basoapically striae on all sides of the root, and a deep root. It differs from the Eocene species H. dockery in the larger size, the less widely separated root branches, the presence of root foraminae or striae, the absence of uvula, and the deeper crown. The new species material, the two teeth from Jaguel Formation, and an indeterminate tooth of Hypolophodon from the Lower Cenozoic of Chile represent the sole records of the genus in the Southern Hemisphere. The shark fauna helped to date the bearing beds.