Cephalomyidae is an extinct family of caviomorph

Caviomorpha

Caviomorpha is the rodent infraorder or parvorder that unites all South American hystricognaths. It is supported by both fossil and molecular evidence.-Origin:...

 rodent

Rodent

Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

s from South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. The specific relationships of the family are uncertain, and affinities to both chinchilloid and cavioid rodents have been supported (McKenna and Bell, 1997; Vucetich et al., 1999; Kramarz, 2001, 2005). Most recently, Kramarz (2005) performed a phylogenetic analysis supporting a relationship to the Cavioidea, as represented by Eocardiidae

Eocardiidae

The Eocardiidae are an extinct family of caviomorph rodents from South America. The family is probably ancestral to the living family Caviidae , which includes cavies, maras, and capybaras and their relatives...

. McKenna and Bell (1997) questioned the validity of the family, placing the cephalomyid genera then known in Dasyproctidae

Dasyproctidae

Dasyproctidae is a family of large South American rodents, comprising the agoutis and acouchis. Their fur is a reddish or dark colour above, with a paler underside. They are herbivorous, often feeding on ripe fruit that falls from trees...

, but Kramarz (2001) subsequently reasserted the distinctiveness of cephalomyids.