Ischyrhiza is an extinct genus of sclerorhynchoid ray from the Late Cretaceous (Cenomanian-Maastrichtian).
It had a large, toothed rostrum closely resembling that of a modern-day sawfish. Despite formerly being classified within a family of extinct sawfish-like rays known as Sclerorhynchidae,[1] phylogenetic analyses indicate that Ischyrhiza, Schizorhiza, and Onchopristis form a distinct clade that groups closer with the extant family Rajidae, which contains the true skates, possibly rendering the suborder Sclerorhynchoidei paraphyletic.[2]
Fossils of the genus have been found in Canada, the United States, the Aguja Formation of Mexico, the Bissekty Formation of Uzbekistan, the Tamayama Formation of Japan, the Dukamaje Formation of Niger, the El Molino Formation of Bolivia, the Quiriquina Formation of Chile, and the Chota Formation of Peru.[3] [4]