Entelodontidae

Entelodonts could get quite large, and in many cases are the largest mammals in their respective ecosystems. The largest entelodont known from a complete skeleton was Daeodon, a North American entelodont that could reach an estimated weight of 750 kg (1650 pounds), The snout was narrow and elongated, especially in later species. The cranium was robust, with strong zygomatic and postorbital arches forming the rim of voluminous temporal fossae, separated by a sharp sagittal crest. However, the rear of the skull was also much shorter than the snout, and the braincase was relatively small. Most of the braincase contributed to large paranasal sinuses and olfactory bulbs at the front, while the cerebrum was underdeveloped. Large olfactory bulbs are likely indicative of a good sense of smell. Moreover, the orbits (eye sockets) are oriented further forwards than in most artiodactyls, suggesting that entelodonts had binocular vision. Compared to other artiodactyls, the jaw was slender at the rear, with a short, triangular coronoid process which is shifted forwards. The mandibular condyle (jaw joint) is set back and below the level of the tooth row. 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. Teeth Similar to pigs, entelodonts retain a large number of teeth, a plesiomorphic trait approximating the ancestral condition for artiodactyls. They have a typical mammalian dental formula of 3.1.4.3 / 3.1.4.3, meaning that each tooth row has three pairs of robust incisors, a pair of large canines, four pairs of pointed premolars, and three pairs of relatively simple and flat molars. This unreduced, or "complete" dentition is the origin of the family's name, which is Greek for "complete teeth". The incisors are closely packed but do not develop a distinct straight chopping surface. They range from chisel-shaped in some entelodonts (Archaeotherium) to massive and rounded in others (Daeodon). The canines have thick enamel and are circular in cross section, unlike most artiodactyls. In older individuals, the tip of the upper canines are often heavily worn or even chipped off. Premolars are triangular when seen from the side, with a large and conical main cusp. They are elongated from front-to-back and widely-spaced, taking up a large portion of the tooth row. The molar teeth are bunodont, with very low and rounded cusps rather than shearing surfaces. Bunodont teeth are common in other omnivorous mammals, including pigs, bears, and humans. The upper molars have up to six cusps and a low crest (a precingulum) on the front edge of the crown. In all but the earliest entelodonts, the lower molars have only four main cusps. The front two cusps (the metaconid and protoconid) may be connected by a horizontal crest and are slightly larger than the rear two cusps. Postcranial skeleton The skeleton is fairly unspecialized in entelodonts. They retain typical artiodactyl skeletal traits, such as a double-pulley ankle joint and paraxonic ("even toed") feet with weight split evenly between the two middle toes. They had four toes on each foot, with the middle two forming small, pointed cloven hooves, while the remaining two were vestigial and likely not externally visible. In larger species, a bison-like spinal hump supported the weight of the heavy head. The limbs were long, and the radius and ulna were fused. Though not fused, the metatarsals (raised foot bones) were long and closely packed. The limb and hoof proportions are consistent with other hoofed animals that run well on open ground but are not built for high speed. ==Paleobiology==

Jaw movement and musculature 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 reinforced pterygoid, zygomatic, and postorbital areas would have supported the forces generated by the temporalis. The size and orientation of the temporalis is similar to carnivorans, where it corresponds to a strong and stable scissor-like (orthal) bite. The same adaptations useful for processing tough plant material would be equally useful for carrion and bones, which could have been major components of the diet for some entelodonts. Some entelodonts may have engaged in active predation, though the extent of this behavior is debated. Several species of modern pigs occasionally engage in predation, and even traditional herbivores like camels show dental wear consistent with scavenging. 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. The wide gape and low skulls of entelodonts would have assisted biting competitions, which are supported by fossil evidence. Large bite marks, including healed punctures, are common on skulls of various American entelodonts. These wounds are concentrated above the sinuses, and are only found on adult specimens. One could easily draw comparisons between these bite marks and the wide range of intraspecific competition over mates or territories in modern artiodactyls. One possible function for the anterior tubercles is as a support for toughened skin, which would have acted as a buffer or display feature during competitive behavior. ==Classification==

Early history The earliest entelodont fossils to be named were described within a short time frame in the 1840s. The first entelodont species known from good fossils was Entelodon magnus, a European species that was named by French paleontologist Auguste Aymard. There is some debate over when Aymard's description was first published; though most authors assumed it was written in 1846, a citation within the article suggests that it was not published until 1848. Auguste Pomel, one of Aymard's contemporaries, described another fossil as Elotherium around the same time. Pomel's volume was likely published in 1846 or 1847, albeit with surviving reprints dating to 1848. Entelodon and Elotherium are almost certainly synonymous, though fossils belonging to the latter name are fragmentary and have been lost, while those of the former were likely described later. 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. The confusion of priority between Entelodon and Elotherium is reflected in the name of their corresponding family. Edward Richard Alston coined the name Elotheriidae in 1878, while Richard Lydekker used the name Entelodontidae in 1883. As with Entelodon, nearly all paleontologists prefer Entelodontidae when referring to the family. 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). • †Paraentelodon • †Proentelodon? ==In popular culture==

's depiction of Entelodon (~1890s)|left|209x209pxIn popular media, entelodonts are sometimes nicknamed hell pigs or terminator pigs. Entelodonts appear in the third episode of the popular BBC documentary Walking with Beasts, where, in the program, the narrator always refers to the creatures as "entelodonts" rather than a more specific genus, such as Entelodon. The same creatures appear in another BBC production, the 2001 remake of The Lost World. Entelodonts were also the main focus of episode 4 of National Geographic Channel's show Prehistoric Predators in an episode titled "Killer Pig". The episode featured a number of claims unproven or disproven by science, such as Archaeotherium (identified as "entelodont") being the top predator of the American Badlands, and evolving directly into the even larger Daeodon (called "Dinohyus" in the episode). ==See also==