''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 of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

, Olmos Formation of the Difunta Group of Mexico, and the Beshtyubin and

Bissekty Formation The Bissekty Formation (sometimes referred to as Bissekt) is a geologic formation and Lagerstätte which crops out in the Kyzyl Kum desert of Uzbekistan, and dates to the Late Cretaceous Period. Laid down in the mid to late Turonian, it is dated ...

s of

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. It was a freshwater

guitarfish The guitarfish, also referred to as shovelnose rays, are a family, Rhinobatidae, of rays. The guitarfish are known for an elongated body with a flattened head and trunk and small, ray-like wings. The combined range of the various species is trop ...

that probably reached a length of , and had teeth adapted for a

durophagous Durophagy is the eating behavior of animals that consume hard-shelled or exoskeleton bearing organisms, such as corals, shelled mollusks, or crabs. It is mostly used to describe fish, but is also used when describing reptiles, including fossil tu ...

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 shel ...

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, t ...

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 characteristi ...

. 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