Heteromyidae

Heteromyidae is a family of rodents comprising kangaroo rats, kangaroo mice, pocket mice and spiny pocket mice, with about 59 species across six genera. The family is endemic to the western United States, Mexico, Central America and northwestern South America, mostly in deserts and grasslands, though the genus Heteromys extends into tropical forests. Heteromyids carry fur-lined external cheek pouches for transporting seeds, along with partially fused neck vertebrae, short forelimbs and enlarged auditory bullae; kangaroo rats have continuously growing teeth while pocket mice have rooted molars.