Like living animals, fossil remains of once-living animals are classified and grouped according to their relationships to each other and to their ancestors.
Gene studies suggest the capybara should be in their own family, Hydrochoeridae, separate from the cavy's family, Caviidae. (Rowe & Honeycutt 2002)
Several generic names have been suggested for living capybara: Hydrochaeris and Hydrochoerus are used most often. (Mones & Ojasti 1986)
Many taxonomists name three capybara subfamilies. (McKenna & Bell 1997)
Prado et al (1998) note there are currently four subfamilies, but two of them are not valid according to cladistic analysis.
Hay (1923) named Hydrochoerus pinckneyi fossils from South Carolina.
In 1926 Hay placed Hydrochoerus pinckneyi in the new genus, Neochoerus. (Kurtén 1980)
Mones and Ojasti (1986) note that many references to Hydrochoerus (=Hydrochaeris) in paleontology literature for North America should actually be Neochoerus and that only one South American fossil species of Hydrochoerus can be distinguished from the living capybara.
Capybara and other animals similar to cavies may have originally arrived in South America from Africa. (Wyss et al 1993)
Ancestors of modern capybara are the cavy-like rodents (cavimorphs)
Capybara family (Hydrochoeridae) needs revision (Deschamps et al 2007)
Geologically oldest capybaras are found in 9 million year-old rocks (Late Miocene) in Argentina (Deschamps et al 2007)
The capybara family was quite diverse during the Miocene and Pliocene; by Pleistocene times it had declined significantly. (Prado et al 1998)
Neochoerus is the most common extinct capybara in North America between 3.6 million years ago (Pliocene) and the end of the Pleistocene (Mones & Ojasti 1986)
A new 2.6 to 3.7 million year-old (Late Pliocene) species of Hydrochaerisdiscovered on island of Grenada in the Caribbean Sea
Late Pleistocene record of Hydrochoeridae in southern California near Oceanside. (Deméré 2005)
Family: Hydrochoeridae - capybaras
Genus: Neochoerus (Hay, 1926)
Species: Neochoerus pinckneyi - Pinckney's Capybara (of North America) (extinct)
Genus: Hydrochaeris (Brunnich, 1772)
Species: Hydrochaeris holmesi - Holmes' capybara (extinct)
Species: Hydrochaeris gaylordi - Gaylord's capybara (extinct)
Species: Hydrochaeris hydrochaeris - capybara (extant)
Species: Hydrochaeris isthmius - Panama capybara (extant)
Casteñada & Miller (2004)
Deschamps et al (2007)
Flynn et al (2005)
Kaspar & McClure (1976)
McKenna & Bell (1997)
Mones & Ojasti (1986)
Prado et al (1998)
Rowe & Honeycutt (2002)
Wyss et al (1993)