Daeodon the Terminator

How the Terminator Pig is thought to have looked like!
Image Credit: Max Bellomio, https://commons.m.wikimedia.org/wiki/File:Daeodon_shoshonensis_.png

Daeodon is an animal that has had a lot of rather intimidating nicknames associated with it over the years. These have ranged from the “Terminator Pig” (which makes me think of a pig wearing sunglasses and travelling through time on a mission to destroy!) to the “Hell Pig” (which suggests a giant boar rising from a fiery pit accompanied by heavy metal!). Even its name “Daeodon” translates as “Dreadful Teeth”, a name that would strike fear into the hearts of dentists everywhere. But what was Daeodon really like? And did it deserve its reputation?

Daeodon belonged to a now extinct branch of the “artiodactyls”, a mammal group that also contains pigs, horses and even whales, known as the Entelodontidae, or “Entelodonts”. In life Entelodonts would have looked superficially pig-like with a long snout, hooved feet, tall shoulder hump, short tail and a round body. The “terminator” and “hell” parts of its nicknames stem from its huge size, Daeodon was the size of a bison, and it’s grotesque looking face which possessed side flanges, bony bumps and fearsome looking teeth. However despite appearances the Entelodonts’ closest relatives are not actually pigs. A study published in 2009 by Michael Spaulding, Maureen O’Leary and John Gatesy found that, whilst studying the ancestry of the artiodactyl group, they were more closely related to the whippomorpha subgroup (which contains hippos, whales and dolphins) than modern pigs. This has changed some reconstructions of entelodonts into a more bulky animal than previously thought, more akin to a land-based hippo than an oversized pig. So maybe the famous nickname of “terminator pig” should now be “terminator hippo”, which is just as horrifying considering how aggressive and dangerous modern hippos are! Entelodonts were a very successful group of mammals. First evolving in Mongolia roughly 40 million years ago during the Eocene they diversified into multiple different species that spread into Europe and North America during the Oligocene and Miocene. Daeodon was in many ways the culmination of this line, being not only the largest entelodont but also one of the last.

The skull of Daeodon showing its strong build and differentiated teeth.
Image Credit: Matt Celeskey, https://commons.m.wikimedia.org/wiki/File:Daeodon_skull.jpg

Roaming the plains of North America from 25-18 million years ago, Daeodon lived alongside a weird menagerie of life consisting of animals both familiar and unfamiliar. Alongside the ancestors of today’s horses and camels were extinct animals like the Chalicotheres, relatives of horses that walked on their knuckles like gorillas and possessed large claws that they used to pull down vegetation, and Hyaenodonts, mammalian carnivores that belonged to the now extinct Creodont group. Standing 1.8 metres tall and weighing roughly half a tonne Daeodon would have been an imposing animal in this environment. The distinctive flanges on its 3 ft. long head covered large cheek bones and were anchor points for large jaw and neck muscles, giving it a very powerful bite. Despite its fearsome appearance however, Daeodon was an omnivore. It possessed differentiated teeth just like in humans; gripping incisors at the front, large canines in the middle and crushing molars at the back. This enabled it to eat almost anything it came across including roots and tubers, fruit, leaves and meat. It would have been a very effective scavenger as a highly developed sense of smell would allow it to locate a carcass accurately from a distance, tracking the smell in a zig-zagging fashion. Furthermore its large size would have enabled it to drive off other animals from the kill. Make no mistake however, Daeodon would have dabbled with hunting live prey as well. It is thought to have been an ambush hunter, using its large size and powerful jaws to overpower and crunch through prey. But it’s not just other animals that Daeodon would have fought. Puncture marks found on the skulls of other entelodont species have shown that they fought each other, whether for mates, territory or both. So in many ways, given its large size and omnivorous lifestyle, Daeodon might have had a similar lifestyle to a modern day Grizzly Bear. Sadly this magnificent beast isn’t around today to give Grizzly Bears a contest. The last Daeodon went extinct around 18 million years ago. This coincided with the first emergence in North America of the large Bear-Dog Amphicyon (see my Amphicyon blog for more!), which had migrated from Asia. This predator, while smaller, was swifter and most importantly; more intelligent. As a result it seems to have partly out-competed Daeodon. Combining this with a climate which was becoming drier as the Miocene progressed resulted in Daeodon being driven to extinction, leaving only their fossils as remnants of a once widespread group.

Speaking of these fossils, the first Daeodon fossils were discovered in 1879 by the American fossil collector Edward Drinker Cope. Cope is a big name in the field of palaeontology, being responsible for the discovery of many extinct species such as the sauropod dinosaur Camarasaurus and the sail backed stem-mammal Dimetrodon. He is also known for his bitter rivalry with fellow American fossil hunter Othniel Charles Marsh. The two were locked in a race to discover and describe the most new species in a rivalry that has been termed “The Bone Wars”. When Cope examined Daeodon he determined it to be a member of the perissiodactyls, a group of mammals that contain modern day Zebras and Rhinos. It was only in 1909 when it was found that this wasn’t the case and it was actually an artiodactyl. For a long time Daeodon wasn’t the most widely known entelodont, with Dinohyus (meaning “terrible pig”) taking that title. However later it was found that Dinohyus and Daeodon, and another entelodont named Ammodon were actually one and the same animal. Because the rules of species dictate that the first name given to a species is the one that is kept Daeodon was the winner out of the three, with Dinohyus and Ammodon becoming synonyms.

A skeletal of Daeodon, showing how the bones all fit together and how big the animal was compared to a human.
Image Credit: bLAZZE92, https://blazze92.deviantart.com/art/Daeodon-shoshonensis-419367474

Entelodonts were a bizarre group of mammals, with Daeodon being the most eye-catching and iconic of them all. It dominated the North American landscape and while its size and power certainly earns it the “Terminator Pig” nickname (minus the pig part of course) that was only one side to it. As well as being a big and intimidating hunter and fighting for what it wanted, Daeodon would have eaten its greens, rolled happily in the mud and napped peacefully in the sun!

References/Further Reading

Spaulding, O’Leary and Gatesy 2009 paper on the family tree of artiodactyls, including who Entelodonts are most closely related to

Spaulding, Michelle et al. “Relationships of Cetacea (Artiodactyla) among mammals: increased taxon sampling alters interpretations of key fossils and character evolution.” PloS one vol. 4,9 e7062. 23 Sep. 2009, doi:10.1371/journal.pone.0007062

Joeckel 1990 paper on entelodont paleoecology and jaw function

Joeckel, R. (1990). A functional interpretation of the masticatory system and paleoecology of entelodonts. Paleobiology, 16(4), 459-482. doi:10.1017/S0094837300010198

A blog, written by Joe Sawchak and published on the Carnegie Museum of Natural History website, about a life size model of Dinohyus named “hyus”. This model was characterised by the weirdly human eyes!

Sawchak, Joe, “Dinohyus: “Terrible Pig” in more ways than one”, Carnegie Museum of Natural History, carnegiemnh.org/dinohyus-terrible-pig-in-more-ways-than-one/

An article, written by Vasika Udurawane and published on Earth Archives, about the rise of the “Terminator Pigs”

Udurawane, Vasika, “Terminator pigs: Rise of the entelodonts”, Earth Archives, 2016, eartharchives.org/articles/terminator-pigs-rise-of-the-entelodonts/

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