Entelodontidae is an extinct family of pig-like artiodactyls (even-toed ungulates) which inhabited the Northern Hemisphere (Asia, Europe, and North America) from the late Eocene[1] to the early Miocene epochs, about 38-19 million years ago.

The cranium was robust, with strong zygomatic and postorbital arches forming the rim of voluminous temporal fossae, separated by a sharp sagittal crest.

The mandibular symphysis (chin) was fused, and the pterygoid bones along the middle of the roof of the mouth were connected by a strong interdigitating suture.

[2][3][4] Similar to pigs, entelodonts retain a large number of teeth, a plesiomorphic trait approximating the ancestral condition for artiodactyls.

[2] The wide and tall temporal fossa allowed for a very large temporalis muscle, which extends from the side of the cranium to the coronoid process of the mandible.

The temporalis was not only large and strong, but also had a long moment arm (and thus higher torque) due to the coronoid process shifting forwards.

The masseter, which extends from the zygomatic arch to the lower rear corner of the mandible, is a major component of the chewing apparatus in herbivorous artiodactyls.

Moreover, the characteristic jugal flanges of entelodonts were covered with muscle scars on the inside, likely attachment points to strengthen the masseter.

Like entelodonts, these mammals use their equivalent projections as a means of providing extra space for the attachment of the masseter muscle, and develop robust cranial bars to resist the resulting forces on the skull.

They are only clearly correlated with the size of the individual, though a few taxa (Brachyhyops and Cypretherium) can be diagnosed by the absence of a specific pair of mandibular tubercles.

The use of the anterior tubercles is unclear; one speculative idea suggests that they served as an attachment point for strong lip muscles in particularly herbivorous entelodonts.

The mandibular condyle was convex and inserted into a strongly concave facet (glenoid) on the zygomatic arch, which would have restricted front-to-back (propalinal) jaw movement.

Unlike the diverse and fully herbivorous pecoran artiodactyls, entelodonts lack specializations for chopping and shredding grass and other particularly fibrous plants.

This conclusion was justified by its pattern of tooth microwear, run through a linear discriminant analysis calibrated by modern herbivorous and omnivorous mammals.

They would have been opportunistic omnivores, capable of digesting a variety of plant and animal matter and moderating their food preferences based on seasonal ability.

[3] In many entelodonts, the canine teeth acquire rounded wear surfaces at their tips, indicating regular use on hard material such as bones.

In some species the bases of the canines are scoured by smooth grooves, a trait consistent with abrasions from sediment-covered plant material such as roots.

[3] Daeodon is known to have had a distinctive type of "piecrust" tooth wear at the tips of the premolars, with a flat dentine surface surrounded by chipped enamel.

Fossils with large scrapes and puncture marks are found throughout entelodont-bearing sites in the American Great Plains, including a skull of Merycoidodon with an embedded incisor of the entelodont Archaeotherium.

Several species of modern pigs occasionally engage in predation, and even traditional herbivores like camels show dental wear consistent with scavenging.

[9] One of the most apparent examples of circumstantial evidence for predation is a fossil found in the White River Formation of Wyoming, representing a cache of partial skeletons and other remains of the early camelid Poebrotherium.

[10][11] Entelodon's tooth microwear showed no overlap with the modern brown bear (Ursus arctos), and it probably did not actively hunt large mammals as part of its normal diet.

[8] The jaw structure and estimated musculature hold numerous lines of evidence indicating that entelodonts could open their mouths unusually wide.

Male hippos engage in head-to-head "yawning" and jaw-wrestling contests, while females attack by approaching from the side and slamming their head into the opponent's body.

One could easily draw comparisons between these bite marks and the wide range of intraspecific competition over mates or territories in modern artiodactyls.

Nearly all historical and modern authors prefer to use Entelodon for the purpose of clarity, even though it would not take priority under strict rules of nomenclature.

Regardless, entelodonts were universally accepted as examples of "primitive" artiodactyls, with unspecialized bunodont teeth in contrast with the strong adaptations for herbivory present in the more "advanced" ruminants.

[14] Various names were erected to encompass living and extinct bunodont-toothed and non-ruminant artiodactyls, such as "Omnivoria" (Owens, 1858), "Bunodontia" (Lydekker, 1883) and "Nonruminantia" (Gregory, 1910).