In 1981, Dr. Robert Hunt of the University of Nebraska uncovered a large carnivore den complex in a nearby hill. The dens had been mainly inhabited by wolf-sized animals called beardogs, the largest carnivores in existence 19 million years ago. Burrowed into ashy sediment that filled an earlier waterhole, these chambers contained numerous fossil skeletons and represented the oldest known denning behavior of large carnivores. Inside were scavenged bones of juvenile rhinoceroses, camels, and oreodonts, probable food sources for the beardogs. The presence of a juvenile and an adult female beardog in the same den chamber suggests the dens were used to care for the young. Some inhabitants probably died simultaneously, perhaps by drowning during a flood or dying in a drought, and sediment later filled the dens and preserved them for discovery millions of years later. Located near the waterhole periphery and burrowed six feet down, the den chambers were similar in size to those of modern wolves and hyenas. Daphoenodon was the largest of the five carnivores found in the dens; besides Daphoenodon, another beardog, a giant wolverine, a small marten, and a tiny fox-like dog were discovered.