''Ischyrhiza'' is an extinct genus of sclerorhynchoid

ray Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (g ...

from the Late Cretaceous and

Early Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (Mya) to the beginning of ...

. 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 Ganopristidae is an extinct family of cartilaginous fish from the Cretaceous belonging to the suborder Sclerorhynchoidei. While the name Sclerorhynchidae is often used for this family, it is a junior synonym of Ganopristidae. This family contain ...

, phylogenetic analyses indicate that ''Ischyrhiza,

Schizorhiza ''Schizorhiza'' is a fossil genus of cartilaginous fish, containing a single accepted species ''Schizorhiza stromeri''. Its fossils are found in rocks dating from the Campanian and Maastrichtian stages; it thus lived between about and million ...

'', and ''

Onchopristis ''Onchopristis'' is an extinct genus of sclerorhynchoid from the Cretaceous of North Africa, Europe, and North America. Its name is derived from the Ancient Greek ''ónkos'' ( ὄγκος, 'barb') and ''prístis'' ( πρίστις, 'saw' or 'sa ...

'' form a distinct clade that groups closer with the extant family Rajidae, which contains the true skates, possibly rendering the suborder

Sclerorhynchoidei Sclerorhynchoidei is an extinct suborder of rajiform rays that had long rostra with large denticles similar to sawfishes and sawsharks. This feature was convergently evolved and their closest living relatives are actually skates. While they ...

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

. Fossils of the genus have been found in Canada, the United States, the

Aguja Formation The Aguja Formation is a geological formation in North America, exposed in Texas, United States and Chihuahua and Coahuila in Mexico, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered f ...

of Mexico, the Bissekty Formation of Uzbekistan, the

Tamayama Formation The Tamayama Formation is a Santonian geologic formation in Japan. Dinosaur remains not referrable to the genus level are among the fossils that have been recovered from the formation.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517- ...

of Japan, the

Dukamaje Formation The Dukamaje Formation is a geological formation in Niger whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel, David B; et al. (2004). "Dinosaur distribution ( ...

of Niger, the

El Molino Formation The El Molino Formation is a Maastrichtian geologic formation pertaining to the Puca Group of central Bolivia. The formation comprises fine-grained sandstones and sandy limestones with stromatolites deposited in a shallow marine to lacustrine env ...

of Bolivia, the Quiriquina Formation of Chile, and the Chota Formation of Peru.The Paleobiology Database
accessed on 8/21/09

References

Prehistoric cartilaginous fish genera Cretaceous cartilaginous fish Paleocene fish Cretaceous–Paleogene boundary Cretaceous fish of Africa Cretaceous Niger Fossils of Niger Cretaceous fish of Asia Fossils of Japan Fossils of Uzbekistan Bissekty Formation Paleogene fish of North America Paleogene United States Cretaceous fish of North America Cretaceous Canada Fossils of Canada Cretaceous Mexico Fossils of Mexico Cretaceous United States Fossils of the United States Demopolis Chalk Prehistoric fish of South America Late Cretaceous animals of South America Cretaceous Bolivia Fossils of Bolivia Cretaceous Chile Fossils of Chile Cretaceous Peru Fossils of Peru Sclerorhynchoidei Fossil taxa described in 1856 {{Cretaceous-fish-stub