''Myledaphus'' is a genus of

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

cartilaginous fish whose fossils are known from

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, the

Midwest The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of the United States. ...

of the

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Olmos Formation The Olmos Formation is a Formation (geology), geologic formation in Mexico. It preserves fossils of plants, hadrosaurs, ceratopsians, tyrannosaurs and the turtle ''Palauchelys'' dating back to the Cretaceous Period (geology), period. See also ...

of the

Difunta Group The Difunta Group is a Group (geology), geologic group in Mexico. It preserves fossils dating back to the Cretaceous Period (geology), period. See also * List of fossiliferous stratigraphic units in Mexico External links

* Geologic ...

of Mexico, and the Beshtyubin and Bissekty Formations of

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. It was a

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does in ...

guitarfish that probably reached a length of , and had teeth adapted for a durophagous diet of animals such as

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two sh ...

s. Most taxonomic authories place the genus in the Rhinobatidae. Two species are known: ''Myledaphus bipartitus'', the type species, and ''Myledaphus araucanus'', named in 2019.

Fossils and age

The most common remains of this fish are

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, te ...

and

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characterist ...

. A study performed on ''Myledaphus'' vertebra from

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in 2013 revealed that ''Myledaphus'' had an estimated maximum age of 16 years. This means that ''Myledaphus'' had a shorter lifespan than that of the modern common guitarfish, by a difference of 8 years.

Fossils and age

See also

References

Further reading