''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
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. 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
''Chelus orinocensis'', the Orinoco mata mata, is a species of freshwater turtle found in northern South America in the Orinoco, upper Rio Negro– Branco and Essequibo basins, and in Trinidad. It was split off from the very similar '' Chelus ...
'' 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
The Castilletes Formation (, N1c) is a fossiliferous geological formation of the Cocinetas Basin in the northernmost department of La Guajira, Colombia. The formation consists of fossiliferous mudstones, siltstones and medium-grained to conglome ...
, Cocinetas Basin
The Cocinetas Basin () is a small sedimentary basin of approximately in northeasternmost Colombia. The wikt:onshore, onshore pull-apart basin is located in the departments of Colombia, department of La Guajira Department, La Guajira at the border ...
, 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
Matamata () is a town in Waikato, New Zealand. It is located near the base of the Kaimai Ranges, and is a thriving farming area known for Thoroughbred horse breeding and training pursuits. It is part of the Matamata-Piako District, which takes ...
'' – Amazon mata mata
*''Chelus orinocensis
''Chelus orinocensis'', the Orinoco mata mata, is a species of freshwater turtle found in northern South America in the Orinoco, upper Rio Negro– Branco and Essequibo basins, and in Trinidad. It was split off from the very similar '' Chelus ...
'' – Orinoco mata mata
*†''Chelus colombianus
''Chelus'' is a genus of large freshwater turtles found in tropical South America. Formerly considered to be a monotypic genus, it now consists of two extant species after '' Chelus orinocensis'' was identified in 2020 from a genetic analysis. ...
'' – Columbian mata mata (Early-Late Miocene)
References
Taxa named by André Marie Constant Duméril
{{turtle-stub