''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'', the ...

cartilaginous fish Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue ...

whose fossils are known from

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, the

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

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 territorie ...

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 of Mexico, and the Beshtyubin and Bissekty Formations of

Uzbekistan Uzbekistan (, ; uz, Ozbekiston, italic=yes / , ; russian: Узбекистан), officially the Republic of Uzbekistan ( uz, Ozbekiston Respublikasi, italic=yes / ; russian: Республика Узбекистан), is a doubly landlocked cou ...

. 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 include ...

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 diet of animals such as clams. 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, tear ...

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 characteristic ...

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

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

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 The common guitarfish (''Rhinobatos rhinobatos'') is a species of cartilaginous fish in the family Rhinobatidae. It is native to the eastern Atlantic Ocean and the Mediterranean Sea. It is a bottom-dwelling fish feeding on crustaceans, other inv ...

, by a difference of 8 years.

Fossils and age

See also

References

Further reading