Echimyidae (from Ancient Greek ἐχῖνος (ekhînos), meaning "hedgehog", and μῦς (mûs), meaning "rat, mouse") is the family of Neotropical spiny rats and their fossil relatives. This is the most species-rich family of hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully arboreal to terrestrial to fossorial to semiaquatic habits. They presently exist mainly in South America; three members of the family also range into Central America, and the hutias are found in the West Indies in the Caribbean. Species of the extinct subfamily Heteropsomyinae formerly lived on Cuba, Hispaniola, and Puerto Rico in the Antilles.
Characteristics
In general form, most spiny rats resemble rats, although they are more closely related to guinea pigs and chinchillas. Most species have stiff, pointed hairs, or spines, that presumably serve for protection from predators.
Many echimyids can break off their tails when attacked. Losing the tip of their tail is reportedly common. This action may confuse predators long enough for the spiny rat to escape. Unlike the tails of some species of lizards, however, the tails of spiny rats do not regenerate. Therefore, the tactic can only be used once in an individual's lifetime.
Most spiny rats are rare and poorly known, but a few are extremely abundant. Various species are respectively terrestrial, arboreal, or fossorial. In general, the arboreal forms are most rat-like in appearance, whilst the burrowing species are more gopher-like, with stocky bodies and short tails. Most species do poorly in conditions of high heat and aridity and are restricted to regions with abundant water. They are almost exclusively herbivorous.
Systematics
The current taxonomic content of the family Echimyidae has been reshaped over time, and its organization into coherent units stems from two realizations. The first is that cladistic approaches applied to morphological characters showed that many traits used to...
