Creodonta ("meat teeth") is a former order of extinct carnivorous placental mammals that lived from the early Paleocene to the late Miocene epochs in North America, Europe, Asia and Africa.

[10] Creodonts were the dominant carnivorous mammals from 55 to 35 million years ago, peaking in diversity and prevalence during the Eocene.

[13] In Oligocene Africa, hyaenodonts were the dominant group of large flesh-eaters, persisting until the middle of the Miocene.

[14] While most were small-to-medium sized mammals, among their number was Sarkastodon, one of the largest mammalian land predators of all time, weighing an estimated 800 kg.

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.

[16] "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.

It stabilized in the mid-20th century as representing oxyaenids, hyaenodonts, mesonychids, and arctocyonids,[20] which were understood as the major groups of flesh-eating placental mammals that were not members of the Carnivora.

[21] More recently, "Creodonta" had been considered to be a nonvalid polyphyletic assemblage of carnivorous placental mammals (and not a natural group), and members of Creodonta being sister taxa to Carnivoramorpha (carnivorans and their stem-relatives) within clade Pan-Carnivora (in mirorder Ferae), split in two groups: order Oxyaenodonta as one group and order Hyaenodonta plus its stem-relatives (family Wyolestidae and genera Altacreodus, Simidectes and Tinerhodon) in the other.

[27] Polly has argued that the only available synapomorphy between oxyaenids and hyaenodontids is a large metastylar blade on the first molar (M1), but he believes that that feature is common for all basal eutheria.

[14] Among primitive creodonts the dental formula is 3.1.4.33.1.4.3, but later forms often had reduced numbers of incisors, premolars and/or molars.

The skull narrowed considerably behind the eyes, producing a distinct splanchnocranium and neurocranium segments of the cranium.

The larger animals, however, were not known until late in the Paleocene with the radiation of the oxyaenids,[12] such as the puma-sized Dipsalidictis and the probably bone-crushing scavenger Dipsalodon.

[35] Certain creodonts (Arfia, Prolimnocyon and Palaeonictis) seem to have experienced the dwarfing phenomenon during the Paleocene-Eocene Thermal Maximum seen in other mammal genera.

A proposed explanation for this phenomenon is that the increased carbon dioxide levels in the atmosphere directly affected carnivores through increased temperature and aridity and also indirectly affected them by reducing the size of their herbivorous prey through the same selective pressures.

[37] During the Central Asia Expedition of 1930 by the American Museum of Natural History, the largest creodont ever discovered was collected: Sarkastodon mongoliensis.

[15] Early creodonts (both oxyaenids and hyaenodontids) displayed the tribosphenic molars common for basal therians.

[39] A similar development can be seen by comparing Oxyaena, Prototomus and Limnocyon with the smaller, more generalized feeders among the creodonts.

However, there is no direct evidence that the existence of large Carnivora caused the extinction of these taxa, and in many cases (in Africa throughout the Early and Middle Miocene, and in North America and Eurasia during much of the Oligocene), hyaenodonts thrived in environments in which large carnivorans such as nimravids and (later) larger amphicyonids were also present as competitors.

Other speculations focus on their limb structure, which limited leg movement to a vertical plane, as in ungulates; they were unable to turn their wrists and forearms inward to trip, slash, or grab prey as some modern carnivores can.

This structure committed them to eating meat almost exclusively, which may have limited their ability to exploit mesocarnivore and omnivore ecological niches.