Creodonta

Creodonta ("meat teeth") is a former order of extinct carnivorous placental mammals that lived from the Early Paleocene (or Late Cretaceous) to the Late Miocene epochs in North America, Eurasia, and Africa. Originally thought to be a single group of animals ancestral to the modern Carnivora, this order is now usually considered a polyphyletic assemblage of two different groups, the oxyaenids and the hyaenodonts, not a natural group. Oxyaenids are first known from the early Paleocene of North America, while hyaenodonts hail from the late Paleocene, or Late Cretaceous, of Europe.

Creodonts were the dominant carnivorous mammals from 55 to 35 million years ago, peaking in diversity and prevalence during the Eocene. The first large, hypercarnivorous mammals appeared with the radiation of the oxyaenids in the late Paleocene. During the Paleogene, "creodont" species were the most abundant terrestrial carnivores in the Old World. In Oligocene Africa, hyaenodonts were the dominant group of large flesh-eaters, persisting until the middle of the Miocene.

"Creodont" groups had an extensive range, both geographically and temporally. They are known from the late Paleocene through the late Oligocene in North America, the early Eocene through late Oligocene in Europe, from the late Paleocene through late Miocene in Asia, and from the late Paleocene to the late Miocene in Africa. While most were small-to-medium sized mammals, among their number was Megistotherium and Sarkastodon, both of which were some of the terrestrial mammalian hypercarnivores. The last genus, Dissopsalis, went extinct about 10 million years ago.

Most modern paleontologists agree both "creodont" families are related to Carnivora, but are not their direct ancestors. It is still unclear how closely the two families are related to each other. In general, classification is complicated by the fact that relationships among fossil mammals are usually decided by similarities in the teeth, but the teeth of hypercarnivorous species may evolve similar shapes through convergent evolution, to deal with the mechanics of eating meat.

"Creodonts" share with the Carnivora, and many other predatory mammal clades, the carnassial shear, a scissors-like modification of upper and lower cheek teeth that was used to slice muscle tissue. This adaptation is also seen in other clades of predatory mammals.