They evolved to become considerably larger than their predecessors, and filled a wide range of niches in late Cenozoic North America, from small omnivores to powerful, bear-sized carnivores, such as Epicyon.

The Borophaginae begins with a group of small fox-sized genera, such as Archaeocyon, Oxetocyon, Otarocyon, and Rhizocyon, in the Orellan through early Arikareean stages.

Often generically referred to as "bone-crushing dogs" for their powerful teeth and jaws, and hyena-like features (although their dentition was more primitive than that of hyenas), their fossils are abundant and widespread; in all likelihood, they were probably one of the top predators of their ecosystems.

According to Xiaoming Wang, the Borophaginae played broad ecological roles that are performed by at least three living carnivoran families, Canidae (which they were a part of), Hyaenidae, and Procyonidae.

Borophagine taxonomy, following Wang et al.[5] (million years=in existence) Cladogram showing borophagine interrelationships, following Wang et al., figure 141:[5] Hesperocyoninae Caninae Archaeocyon Oxetocyon Otarocyon Rhizocyon Cynarctoides Phlaocyon Cormocyon Desmocyon Paracynarctus Cynarctus Metatomarctus Euoplocyon Psalidocyon Microtomarctus Protomarctus Tephrocyon Tomarctus Aelurodon Paratomarctus Carpocyon Protepicyon Epicyon Borophagus According to an analysis of the fossil record of North American fossil carnivorans, the decline of borophagines from a diversity of about 30 species 15 million years ago to extinction was largely driven by competition with felids and canines.