 The holotype of the younger species "O. leptodon" was found with both tusks "in situ", the right one long, the erupted portion , the left tusk was only but a wear facet indicates that it was erupted.The skull of "O. leptodon" differs from that of "O. peruvianus" in the absence of a premaxillary foramina and the presence of a dorsal fossa (shallow depression) on the premaxilla.This fossa suggests the presence of a melon in "O. leptodon", an organ either absent or strongly reduced in "O. peruvianus".