When he wasn’t hating his paleontology archrival in some tangible way, Edward Drinker Cope* was discovering and naming fossil fauna. In 1892 he found a dog-like creature with skeletal features suggesting its jaws could crush bones with impunity. These features included oversized premolars placed in a short, robust jaw, which provided wide attachment areas for muscles. Drinker named the beast Borophagus (gluttonous eater). Based on the presence and measurements of other skeletal parts found across North America, it roamed widely between 16 and 2 million years ago and weighed about 50 pounds. Its mighty bite force allowed it to occupy a unique ecological niche, presently represented in Africa by the spotted hyena. Because “Boro” could crack open large bones and savor the marrow within, it could stay back and let other large carnivores finish their meal and then enjoy their leftovers. Or maybe they hunted in packs as hyenas do, devouring large prey, bones and all, within a few frenzied minutes. In that case, Boro would have an advantage if it could snap off an entire leg and trot off to enjoy it in peace.
Because Drinker and subsequent paleontologists had just the bones, they were unable to determine anything about Boro’s behavior. Was it a hyena-like pack animal? A scavenger? A predator? Answers have come recently from a surprising source—its fossilized poop.
While boating on Turlock Lake, east of Modesto, California, an amateur fossil collector recognized a blob on the shore as a coprolite, scientific parlance for feces turned to stone. It had fragments of bone visible near the surface, so the collector surmised that the donor was a large carnivore, and Boro was the only known carnivore from that time in that area. He dug around and recovered 14 coprolites, which became the material for a 42-page scientific publication.
The fact that Boro and company dropped feces in clusters, which is how wolves and spotted hyenas mark territory, implied to the investigators that they were social animals and that the fossil collector had come across their outhouse. Computed tomography analysis of the coprolites revealed bone fragments that came from ribs or limbs of animals as large as 220 pounds, the size of today’s mule deer. Although some of the bone fragments were nearly 2 ½ inches long, most were in the quarter-to-half-inch range, which made the source generally unidentifiable, although one clearly came from a bird wing and another from a beaver jaw. The investigators suggest that Boro’s habit of crushing bone accelerated recycling of the contained nutrients into the food web and remark that no animal took Boro’s place following its extinction. Modern day carnivores living in the area (coyotes, foxes, cougars) do not have Boro’s bone-crushing capabilities, which indicates a fundamental shift in food web dynamics—quite a lesson derived from a latrine.