Ischyrhiza

Ischyrhiza is an extinct genus of sclerorhynchoid ray from the Late Cretaceous (Cenomanian-Maastrichtian).^[1]

Ischyrhiza Temporal range: Late Cretaceous[1] PreꞒ Ꞓ O S D C P T J K Pg N
Ischyrhiza mira rostral spines
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	Rajiformes
Suborder:	†Sclerorhynchoidei
Genus:	†Ischyrhiza Leidy, 1856
Type species
†Ischyrhiza mira Leidy, 1856
Species
†I. antiquus †I. avonicola Estes, 1964[2] †I. marrocanus †I. mira Leidy, 1856[3] †I. stromeri †I. texana Cappetta & Case 1975 †I. serra Nessov, 1997 †I. nigeriensis Tabaste, 1963 †I. hartenbergeri Cappetta, 1975 †I. germaniae Weiler & Albers, 1964 †I. viaudi Cappetta, 1981 †I. antiqua (Leidy, 1856) †I. radiata (Clark, 1895)

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,^[4] 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.^[5]

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.^[6][7]

References

1. Williamson, Thomas E.; Kirkland, James I.; Lucas, Spencer G. (1993). "Selachians from the Greenhorn Cyclothem ("Middle" Cretaceous: Cenomanian–Turonian), Black Mesa, Arizona, and the Paleogeographic distribution of Late Cretaceous selachians". Journal of Paleontology. 67 (3): 447–474. doi:10.1017/s002233600003691x.
2. ESTES, R. (1964) Fossil vertebrates from the Late Cretaceous Lance Formation, Eastern Wyoming. University of California Publications in Geological Sciences, 49: 1–180, 73 fig., 5 pl.
3. Leidy (1856) - Notice of remains of extinct vertebrated animals of New-Jersey, collected by Prof. Cook of the State Geological Survey under the direction of Dr. W. Kitchell. Proceedings of the Academy of Natural Sciences of Philadelphia, 8: 220–221
4. "Fossilworks: Sclerorhynchidae". fossilworks.org. Retrieved 17 December 2021.
5. Villalobos‐Segura, Eduardo; Underwood, Charlie J.; Ward, David J. (2019). "The first skeletal record of the enigmatic Cretaceous sawfish genus Ptychotrygon (Chondrichthyes, Batoidea) from the Turonian of Morocco". Papers in Palaeontology. 7: 353–376. doi:10.1002/spp2.1287. ISSN 2056-2802. S2CID 210302939.
6. Ischyrhiza at Fossilworks.org
7. The Paleobiology Database accessed on 8/21/09