Heteromyidae

Heteromyidae is a family of small to medium-sized New World rodents in the order Rodentia. It comprises two subfamilies and several genera, including Dipodomys (kangaroo rats), Microdipodops (kangaroo mice), and the pocket mice genera Perognathus, Chaetodipus, and Heteromys. Members are distributed primarily in arid and semiarid regions of the Americas, from the southwestern United States through Mexico and Central America to parts of South America.

A defining feature is the presence of fur-lined external cheek pouches used to transport seeds and other food. In the hopping lineages (kangaroo rats and kangaroo mice), long hind limbs and a long tail support saltatory locomotion. Dentition is typical of rodents, with high-crowned molars adapted for grinding abrasive seeds.

Ecology and behavior: Most species are granivorous, with diets dominated by seeds and desert vegetation; some also eat green matter or insects. They are often nocturnal or crepuscular and many species live in shallow burrows or surface runways. Kangaroo rats, in particular, have efficient water-use biology and can survive with little free water.

Evolution and systematics: The family is part of the superfamily Geomyoidea and has a fossil record dating to the Oligocene–Miocene of North America, with diversification linked to aridification of habitats.