''Colosteus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of colosteid

tetrapod Tetrapods (; ) are four-limb (anatomy), limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant taxon, extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (p ...

from the Late Carboniferous (late Westphalian stage) of

Ohio Ohio () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Of the List of states and territories of the United States, fifty U.S. states, it is the List of U.S. states and territories by area, 34th-l ...

. Its remains have been found at the Linton site in

Saline Township, Ohio Saline Township is one of the fourteen townships of Jefferson County, Ohio, United States. The 2010 census found 1,353 people in the township, 933 of whom lived in the unincorporated portions of the township. Geography Located in the northeas ...

, where it is one of the most common tetrapods, and at the Five Points site in

Mahoning County, Ohio Mahoning County is a county in the U.S. state of Ohio. As of the 2020 census, the population was 228,614. Its county seat and largest city is Youngstown. The county is named for a Lenape word meaning "at the licks" or "there is a lick", ref ...

. It was an elongate, aquatic form with a flattened and pointed head, greatly reduced limbs, two

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

ry tusks, and heavy scalation. It would have reached about 1 m (3.2 ft) in length. It was originally described by

John Strong Newberry John Strong Newberry (December 22, 1822 – December 7, 1892) was an American physician, geologist and paleontologist. He participated as a naturalist and surgeon on three expeditions to explore and survey the western United States. During the C ...

in 1856 as a new species of the palaeonisciform fish

'' Pygopterus''. In 1869,

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 intereste ...

erected a new genus of " batrachian", ''Colosteus'', containing the species ''C. crassicutatus'', ''C. foveatus'', and ''C. marshii'', based on Linton material lent to him by Newberry. Cope later realized that the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

of his ''Colosteus crassicutatus'' was also the holotype of Newberry's earlier ''Pygopterus scutellatus'', and combined the two as ''Colosteus scutellatus''. ''Colosteus foveatus'' was later determined to be a junior synonym of '' Isodectes obtusus'', and ''Colosteus marshii'' was given its own genus, '' Ptyonius''

References

Extinct animals of the United States Carboniferous tetrapods of North America Fossil taxa described in 1871 Taxa named by Edward Drinker Cope {{paleo-amphibian-stub