† H. ballesterensis † H. gaylordi † H. hesperotiganites H. hydrochaeris H. isthmius The genus Hydrochoerus contains two living and three extinct species of rodents from South America, the Caribbean island of Grenada, California and Panama.

Molecular results have consistently suggested Hydrochoerus is most closely related to Kerodon (the rock cavies), and the two evolved from within the Caviidae.

[1] Based on use of a molecular clock approach, Hydrochoerus appears to have diverged from Kerodon in the late Middle Miocene (about 12 million years ago).

The fossil species inhabited Buenos Aires Province in Argentina (H. ballesterensis) and the Caribbean island of Grenada (H. gaylordi).

[8] Fossils of unspecified Hydrochoerus have been found in Late Pleistocene to Holocene sediments of Curití, Santander, at an altitude of 1,500 m (4,900 ft) in the Eastern Ranges of the Colombian Andes.