A Short-Faced Bear's Mammoth Picnic

The stench emanating from the putrefying mammoth carcass carried for miles.

Though kept out of the sun by the long shadows of the surrounding pine trees, the corpse reeked as the flesh, sinew, and bone of the mammoth's body were slowly parceled out into the ecosystem by scavengers. The woolly elephant's eyes had been pecked out long ago, and the intricate musculature of its trunk lay in tatters, but there was still plenty of meat to go around.

The grisly death site buzzed with activity as less magisterial creatures went about their dirty work. Black birds jostled for the best access to blood-caked fissures opened up in the mammoth's hide, insects injected the beginnings of the next generation into what would serve as both cradle and pantry, and bacteria continued their surreptitious breakdown of the stinking hulk. Yet the olfactory lure that such a rich source of fat and flesh had not gone unnoticed by other more imposing scavengers.

At a distance it was difficult to see. The dense ranks of trees obscured its approach as it loped through the forest. It was not in a hurry, it could not smell any others like itself around, but it was hungry. It let out low huffs as it walked, not out of physical exertion but of anticipation, announcing its approach as the squabbling birds fluttered to the safety of branches just out of reach.

Had it not been so formidable a predator it would have almost been a comical sight. It was an immense bear, larger than any of its living relatives, but it looked as if it had been made out of mismatched parts. Its front legs were extraordinarily long, placing its shoulders so high that the beast almost looked hunchbacked, and its face looked like that of a grizzly bear that had run head-first into a wall at speed. This was Arctodus, the short-faced bear.

The carnivore snuffled the air as it approached the fallen behemoth. That the meat was not fresh did not matter. Normally it would have to chase down its prey, but now all it had to do was defend its prize. Even if others arrived it still would have time to fill its belly with flesh, enough to last it at least a few days. After locating a wound on the mammoth's foot, one that exposed the rich pocket of fat inside, the bear set its powerful jaws to work.

This scene is imaginary, but it is based upon fact. A little more than 14,500 years ago both mammoths and short-faced bears lived in and around a prehistoric conifer forest that existed in what is now Virginia's Saltville Valley. Even better, in a new paper published in the journal Boreas, paleontologists Blaine Schubert and Steven Wallace describe evidence that at least one Arctodus may have had itself a mammoth picnic.

The Saltville site has been studied on and off for about a hundred years, and much of the material dug out of it (especially in terms of plants and small mammals) has yet to be described. Even so, the site has long been known for producing the bones of large herbivorous Pleistocene mammals. American mastodon, mammoth, musk ox, bison, horse, and elk bones have all been found at the site, but there has been no sign of any carnivores. (Or, if there were any carnivore bones found at the site, no one took the trouble to describe them.)

As Schubert and Wallace report, however, there is now evidence that at least two large carnivores lived in the same area at the same time. The most direct evidence comes from a partial right lower jaw bone with a molar tooth still embedded in it. It belonged to a very large bear, and the details of the teeth and shortening of the jaw (indicating a short face) allowed the researchers to narrow down their list of candidates to Arctodus simus, popularly known as the "short-faced bear." In fact, compared to other skeletons from this species, this individual from Virginia appears to have been especially snub-nosed.

The second line of evidence comes from mammoth bones found at the same site. The scientists describe several parts of a mammoth ankle and foot that were chewed on by carnivores. The question is, "What kind of carnivores did the damage?"

One of the bones, the calcaneus (or heel bone) was bitten completely through by a predator with a large canine tooth. Only two known Late Pleistocene carnivores were large enough to inflict this type of damage; the American lion (Panthera leo atrox) and the short-faced bear. As big cats typically avoid chewing on bones, however, the bear is the more likely culprit.* This is consistent with the results of radiocarbon dating carried out on the mammoth bones and the bear jaw. The two animals lived within about 340 years of each other, so it is likely that both coexisted in the same place at the same time.

*[The authors point out, however, that American lions are often found with broken teeth. This suggests that they more regularly bit through bone and chewed hard parts of carcasses than their modern relatives in Africa and India. Though no remains have been found of the American lion at the Saltville site, it cannot be ruled out as a suspect.]

Yet there are other mammoth bones that show a different damage pattern. An astragalus (ankle bone) from the same mammoth is marked by a series of cone-shaped depressions. These tooth marks are more consistent to damage done by a large wolf than a bear, and the authors hypothesize that a dire wolf (Canis dirus) chewed on this particular bone. This means that there were at least two large carnivores living in the vicinity of the Saltville site around 14,500 years ago.

But why would these carnivores have been gnawing on the mammoth's feet? Surely there were meatier parts of the mammoth's body that would have been preferred by these large scavengers. Contrary to what might be expected, mammoth feet probably had a fair bit of meat and fat on them. When their skeletons are reconstructed in museums mammoths look like they are standing on tip-toe, and in life they would have had a pad of flesh behind those foot bones to create a big, round foot as seen in living elephants. (See illustration above.) A mammoth foot would probably good eating for a hungry carnivore.

Even so, a foot may not be as enticing to a large carnivore as viscera from the body cavity or flesh that surrounded the limbs, so perhaps this particular mammoth died in a mud hole or other feature that covered most of its body. This would leave only a few bits (like the foot) sticking out above the surface. The authors note that the uncompletely-excavated mammoth skeleton, though unarticulated, is pretty well preserved and appears to have been covered quickly. If this was the case, then scavengers may have only fed upon what was poking above the encasing sediment. It may even be possible that the mammoth was completely buried, began to decay, and was only later partially uncovered by moving water or digging by scavengers.

Unfortunately our present perspective makes it very difficult to reconstruct such past events, but I still find this fossil evidence fascinating. We now have evidence that at least two, and maybe even three, species of large, extinct carnivores lived in what is now western Virginia only ~14,500 years ago. The chewed-up mammoth bones, whispers from the fossil record, speak to scenes from an ancient past that is just beyond our reach.

SCHUBERT, B., & WALLACE, S. (2009). Late Pleistocene giant short-faced bears, mammoths, and large carcass scavenging in the Saltville Valley of Virginia, USA Boreas, 38 (3), 482-492 DOI: 10.1111/j.1502-3885.2009.00090.x