Reconstructing a monster bear
Several years ago I was approached by the BBC and asked to produce an accurate reconstruction of the giant short-faced bear, Arctodus simus, to be used by a team of 3D artists in order to create life-like animations of the animal. I had drawn Arctodus before but this project required a more in-depth approach, so I set to review all the available information about the anatomy and body proportions of this amazing ursid.
I consulted with paleontologist Paul Mattheus from the university of Alaska in Fairbanks who sent me his Phd thesis along with a wealth of data about the giant bear. With all those figures and measurements I put together a detailed reconstruction of the beast’s skeleton, based mostly on the nearly complete specimen from Fulton County in Indiana, but complemented with bits from other findings. One especially nice skull from Alaska allowed me a detailed restoration of the animal´s head.
In this collage you can see my drawings for the reconstruction of Arctodus simus, from a working sketch of the skeleton to a restoration of the animal’s musculature and soft-tissue outline and a detailed rendering of the head
The creature that emerged from those drawings was quite impressive. With especially long limb bones, it attained a shoulder height of 1.75 meters -while standing on all fours the animal’s eyes would be level to yours! The reconstructed head had a short face indeed, but on top of that the head looked relatively small for the animal’s massive body. Seen from the front, Arctodus also looked tall, narrow and small-headed relative to a modern brown bear.
The next step was to set the animal in motion. The relatively long limbs of Arctodus led some paleontologists to infer that it would be a good sprinter, a very active predator catching speedy prey on the run. But Mattheus’ analysis of the giant bear’s anatomy led him to a different conclusion: Arctodus would move around at moderate speeds with an efficient pace, with more endurance than speed, which in his view was an adaptation for covering huge distances in search of carrion that it would then appropriate using its huge bulk to expel other predators. In other words, the giant short-faced bear would have been a kleptoparasite. Even its great stature when standing on its hind legs would allow it to scan the horizon for any sign of a recent kill.
This second batch of sketches shows the pacing walk of Arctodus and the bipedal posture it would adopt now and then to scan its surroundings. Finally there is a full-color rendering of the living animal
Was that the real ecological niche of Arctodus? Well, if the dentition of an animal is our main guide to inferring its diet, then Arctodus was not a specialized scavenger, for one thing it didn´t nearly have the refined adaptations of a hyena for cracking bones. The teeth of Arctodus were, in spite of differences in detail, bear teeth, and that means a broad-spectrum diet. It could certainly steal kills from most predators around it, but it could also consume vegetable matter and kill its own prey now and then. Its wide distribution in North America indicates a considerable habitat tolerance, and probably a high degree of adaptability, but not enough to survive the wholesale extinction of large mammals at the end of the Pleistocene. As a result, now we need to resort to paleobiological reconstruction if we want to have a reasonable idea of what it looked like and how it behaved. Sad, but better than nothing!