''Chelus'' is a genus of large freshwater

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

s found in tropical

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. Formerly considered to be a

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

, it now consists of two extant species after '' Chelus orinocensis'' was identified in 2020 from a genetic analysis.

Evolution

Fossils of the extinct †'' C. colombianus'' have been found in Venezuela, Colombia, and Brazil, including a skull dating to the

early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

(~ 16 m.y.) of the Castilletes Formation, Cocinetas Basin, in

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

. The fossil shows that the skull morphology of ''Chelus'' has been almost unchanged since the Miocene.

Species

There are two extant recognized species in this genus and one extinct species: *'' Chelus fimbriatus'' – Amazon mata mata *'' Chelus orinocensis'' – Orinoco mata mata *†'' Chelus colombianus'' – Columbian mata mata (Early-Late Miocene)

References

Taxa named by André Marie Constant Duméril {{turtle-stub