| Scelidodon, Mylodontidae, Scelidotherium, Glossotherium, Nematherium|
Catonyx is an extinct genus of ground sloth of the family Mylodontidae, endemic to South America during the Late Pleistocene epochs. It lived from 126,000—10,000 years ago, existing for approximately 0.116 million years. The most recent date obtained is about 9600 B.P.
Catonyx was named by Ameghino (1891). It was assigned to Scelidotheriinae by Gaudin (1995).
Fossils have been uncovered in Brazil and Uruguay.