Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
Back to prehistory … and from those charming little proto-mammals, we jump now to a fearsome bunch of their descendants! These are the Entelodonts, commonly known as Terminator Pigs or Hell Pigs. I've already covered Cypretherium in its own article, but I enclose its picture here again for comparison with the other two.
Entelodonts weren't really pigs, though they look pig-like with their barrel-bodies, huge heads and short necks. They are sometimes considered relative of pigs, but some scientists consider them to be more closely related to hippos, dolphins and whales. They were distinct as a family already by 38 million years ago, the middle Eocene, and likely evolved in Asia. At their peak, they were abundant in Europe, Asia and North America, but never seem to have reached Africa. They went extinct in the early Miocene, about 16.3 million years ago.
The name 'Entelodon' means 'perfect (or complete) teeth'. Their teeth were indeed wondrous, they were some of the toothiest land mammals around. But actually this refers to their dentition being complete, meaning they had a full set: incisors, canines, premolars and molars, without any gaps. This is 'primitive' compared to most living hoofed mammals, who for instance miss some of the teeth like the canines or eye teeth, the incisors (especially on the upper jaw), and frequently have large gaps or diastema interrupting their tooth rows. Entelodonts had general-purpose teeth, with huge incisors, long and sharp, curved canines, and low but sturdy, multi-cusped cheek teeth. They could have chewed plants, macerated meat, and even crunched up bones.
Also characteristic of entelodonts were their huge skulls. The largest species had skulls of almost a metre/yard in length, larger than that of the extant hippopotamus or the white rhinoceros. Most of the skull was mouth, and the jaws could likely open very wide. They did not have the flat snouts characteristic of pigs, but rather blunt muzzles, perhaps with a wet dog-like snout. Two features stand out. All the ones we know, had huge, flaring cheekbones (technically termed jugals). These likely were attachment sites for very strong jaw muscles. They also contributed to the animals' intimidating appearance. Second, most entelodonts also had strange, wart-like bony knobs in pairs along the margins of their lower jaws. These might also have supported muscles, but I am personally not sure, because their position towards the front of the jaw would give muscles attached to them a very weak leverage for jaw-closing. More likely, they were for display. Together with the pointy cheekbones and excessive teeth, these would enhance the fearsome face factor (to use the proper scientific term) even more. Entelodonts had tiny brains for their size, but the olfactory bulbs (dealing with the sense of smell) were comparatively large, meaning that scent would have been important to them.
Behind the skull, the body was short, deep and powerful. Long vertebral processes in the neck and shoulder region likely supported a hump of thick muscles and tendons to lift the heavy head with. The forequarters were much more heavily built than the hindquarters. The tail was short and thin.
The legs of entelodonts were surprisingly slender. Most of the muscle moving the legs were in the upper portions. The feet had only two functional toes, tipped with hooves. This means that they were likely fast runners for their bulk. Nothing living at the time could have predated on adult entelodonts, so the running capability would not have been for escaping predators, but for catching their own prey.
That entelodonts were predators we know not just from inferences from their builds and dentition. There is also other evidence. Bones of various herbivorous species, from rhinos to small camels, were found with bite marks on them that likely were made by entelodonts. 'Caches' of bones of the small camel Poebrotherium (treated in my entry on ancient camels were found, suggesting that these were a store of meat by an entelodont (likely Archaeotherium to last into lean times. There has even been a trackway found, interpreted as showing a Subhyracodon (a small rhino) being chased by an Archaeotherium.
Apart from hunting their own prey, entelodonts might also have fed on carrion. In addition, their generalist dentition would have enabled them to feed on a variety of plant foods, should they be unable to attain the more nutritious meat. Their running adaptations show that they likely inhabited plains, but they might also have entered and lived in forests to some extent.
Here are three representative entelodonts. Cypretherium, the smallest well-known species, I've covered already (link above). Archaeotherium or 'ancient beast' is the one most abundantly known from fossils. It lived in North America from the late Eocene to the late Oligocene epoch, quite a successful run. Indeed it was quite a successful runner, as noted above likely capable of chasing down fleet-footed prey. Archaeotherium varied in size from as big as a pig to the size of a cow. I based my picture of it here on a famous reconstruction by noted paleo-artist Charles R. Knight.
The last one, Daeodon ('dreadful tooth'), was the last surviving entelodont in North America (and perhaps anywhere). It is sometimes known by an alternative name, Dinohyus ('terrible pig'). It was the size of a bison (or as uncultured Americans might call it, a buffalo). This also makes it the largest entelodont known. Its huge skull reached 90 cm/1 yard in length. Daeodon had comparatively less flaring cheeks than Archaeotherium, and the knobs on its lower jaws were smaller, too. It likely lived similarly to other entelodonts. It was rivalled, but likely not exceeded, in size by the earlier-living, Asian Paraentelodon.
A few other entelodont species are known from rarer and more fragmentary remains. The very earliest include Eoentelodon from Asia and Brachyhyops from America. Both were rather small. Entelodon itself, for which the whole group was named, lived in Europe and was similar to Archaeotherium, but is known from far less complete fossil material. It was the first one to be described, in 1846.
Entelodonts suffered from the rise of large and well-adapted carnivores, who outcompeted them for hunting, while other new, large ungulates such as deer and antelopes became much better at browsing or grazing. Their strange and imposing forms vanished from the landscape, and nothing quite like them was ever seen again.