Hyaenodon ("hyena-tooth") is the type genus of the Hyaenodontidae, a family of extinct carnivorous fossil mammals from Eurasia, North America, and Africa, with species existing temporally from the Eocene until the middle Miocene, existing for about 26.1 million years.[1] The various species of Hyaenodon competed with each other and with other hyaenodont genera (including Sinopa, Dissopsalis, and Hyainailurus), and played important roles as predators in ecological communities as late as the Miocene in Africa and Asia and preyed on a variety of prey species such as primitive horses like Mesohippus and early camels.[2] Species of Hyaenodon have been shown to have successfully preyed on other large carnivores of their time, including a nimravid ("false sabertooth cat"), according to analysis of tooth puncture marks on a fossil Dinictis skull found in North Dakota.[3]