The Plundering Dog of Hagerman
One of the truly remarkable aspects of the fossil fauna of Hagerman is the wide variety of carnivores represented. Out of the 105 different species of vertebrates recorded, 14 are carnivores and include dogs, cats, bears and members of the weasel family. Of the two dogs found at Hagerman, one fits our idea of what a dog should look like, as it is the ancestor to our modern coyote. The other dog represents a lineage that has no living relatives but at one time was more widespread and diverse than the group we think of as the modern canids. This other group of dogs is known as the borophagines (boro = carrion or flesh and phagus = to eat) and at Hagerman is represented by the species Borophagus direptor.
In North America some of the borophagine dogs, including Borophagus, filled the ecological niche that is represented by hyenas in Africa today. Like modern hyenas, Borophagus had a proportionately large head which was broad and strong reflecting the powerful jaw muscles that would have allowed them to crush bones. Also like modern hyenas, the muzzle and jaw were shortened to increase the leverage of the jaw for bone crushing. Borophagus was not as large as today's hyena but was about the size of a small wolf.
Previous records of Borophagus at Hagerman have been scarce and knowledge of its presence has been based on a single upper canine and a jaw lacking teeth. During a project locating survey markers, the back portion of a left jaw of Borophagus was found with the large lower molar in place. This specimen will greatly add to our understanding of this species at Hagerman and permit more detailed comparison with specimens from other localities. We know that generally borophagine dogs increased in size through time. The Hagerman specimen is larger than its earlier ancestors but smaller than later species.
Borophagus direptor is the earliest species of Borophagus and besides Hagerman has only been found at two other localities: Coso Mountains in California, and Sawrock Canyon, Kansas. Its larger descendent Borophagus diversidens is better known and has been found at a number of locations.
This article originally appeared in The Fossil Record, May 1994
Did You Know?
The zebra-like horse fossil Equus simplicidens was originally named Plesippus shoshonensis by Dr. Gidley, Smithsonian paleontologist, who led the 1929 excavation at Hagerman. He felt the fossil was different enough to represent a new species distinct from any other fossil horses.