''Pachyrhizodus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

that lived during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

in what is now Europe, North America, South America, and Oceania. Many species are known, primarily from the Cretaceous of England and the midwestern United States.

History and discovery

''Pachyrhizodus'' fossils were first collected from

Cambridgeshire, England Cambridgeshire (abbreviated Cambs.) is a county in the East of England, bordering Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the ...

in the 1840s and were very fragmentary, only a partial maxilla (SMB.9097) and were described as a species of ''Raphiosaurus'' in 1842 by

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owe ...

. The type remains of ''Pachyrhizodus'' consisted of a maxilla (BMNH 49014) from the Lower Cretaceous of Sussex, England and was originally thought to be a mandible that

Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history. Spending his early life in Switzerland, he rec ...

dubbed ''Pachyrhizodus'' in 1850,Dixon, F. (1850): Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex. – 422 pp.; London (Longman, Brown, Green & Longmans). with Frederick Dixon creating the species name ''basalis'' for the specimen. Over the next few years, many ''Pachyrhizodus'' species would be named only from England until in 1872,

Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested ...

described large remains from the

Smoky Hill Chalk The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil rich geological formation, known primarily for its exceptionally well-preserved marine reptiles. Named for the Smoky Hill River, the S ...

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...

of several new species. During the 19th century, several complete and partial skeletons of ''Pachyrhizodus'' were collected from England, many of which belonging to ''P. basalis'' and ''P. subulidens''.Forey, P. L. (1977)
The osteology of Notelops Woodward, Rhacolepis Agassiz and Pachyrhizodus Dixon (Pisces: Teleostei)
Bull. Brit. Mus. Nat. Hist. (Geol.), 28, 125–204. In 1899, Alban Stewart described the mandibles of another species, ''P. minimus'', from Kansas and it is the most commonly discovered species of ''Pachyrhizodus''. Since the 19th century, many complete skeletons and species have been described from many regions.Giersch, S., Frey, E., Stinnesbeck, W., & González González, A. H. (2010)
Pachyrhizodus caninus Cope, 1872 (Teleostei, Crossognathiformes) from the early Turonian of Vallecillo (Mexico).
''Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen'', ''258'', 219-228. ''P. caninus'' specifically has been discovered in the United States, Mexico, and New Zealand.Shimada, K. (2015)
Body form and paleoecology of the large Late Cretaceous bony fish, Pachyrhizodus caninus.
''Cretaceous Research'', ''52'', 286-291.

References

Bibliography

* * {{Taxonbar, from=Q7122211 Crossognathiformes Prehistoric ray-finned fish genera Cretaceous bony fish Cenomanian genus first appearances Maastrichtian genus extinctions Late Cretaceous fish of North America Cretaceous Canada Fossils of Canada Cretaceous United States Mooreville Chalk Late Cretaceous animals of South America Cretaceous fish of South America Cretaceous Colombia Fossils of Colombia Cretaceous fish of Europe Cretaceous England Fossils of England Cretaceous Sweden Fossils of Sweden Fossil taxa described in 1850