Grad student discovers new species of fossil dog

About 12 million years ago, an animal roamed the coast of eastern North America, hunting deer- and pig-like relatives and eating a fair amount of plant material, as well. This coyote-sized dog, named Cynarctus wangi, had powerful jaws and broad teeth, and probably hunted in packs.
And until recently, researchers didn’t know C. wangi existed at all.
This new species of fossil dog was identified by Steven E. Jasinski, a doctoral student in the Department of Earth and Environmental Science in the School of Arts & Sciences, and his colleague Steven C. Wallace, a professor at East Tennessee State University and curator at the East Tennessee State University National History Museum at the Gray Fossil Site. Jasinski is advised by Peter Dodson, a professor of paleontology in the Department of Earth and Environmental Science and professor of anatomy in the School of Veterinary Medicine.
The fossil was discovered by an amateur collector along the beach under the Choptank Formation in Maryland’s Calvert Cliffs region. The collector donated the fossil to the Smithsonian Institution, where researchers presumed it was a known species of borophagine dog called marylandica.
When Wallace told his colleague about the specimen at the Smithsonian, Jasinski says his interest was piqued.
“I still thought it was probably referring to some animal that we were already aware of and knew,” Jasinski explains. “After quite a bit of research and deductive reasoning … that was not remotely what I thought.”
Crucial to Jasinski and Wallace’s discovery were marks on the fossil dog’s teeth. The team compared the fossil dog’s occlusal surfaces, where the bottom and top teeth meet, to those of known specimens. Jasinski says the teeth of the fossil dog had distinct marks, which indicated that this species had a much different diet than other species in the borophaginae subfamily.
“We were able to tell by what we had in front of us, this animal was … eating a different amount of meat than what was already known,” Jasinski says.
Unlike hypercarnivores such as present-day domestic cats, which eat about 95 percent meat in their diets, or dogs, which eat about 70 percent meat, Jasinski says the fossil dog actually had a diet that closely resembles that of a bear: One-third of C. wangi’s diet came from meat, and the rest came from insects, fruit, and berries.
Because there is relatively little left of the fossil dog, Jasinski says their knowledge about the species is limited. They can tell, however, that C. wangi was coyote-sized and represents one of the last surviving borophagines. It was likely outcompeted by ancestors of present-day wolves, coyotes, and foxes.
Jasinski, who is finishing his second year in the Ph.D. program, is focusing a large portion of his studies on predatory mammals through time, seeking to understand how those animals would have evolved and changed over the years. He hopes that looking at how those species have changed over time can help inform future efforts to save other predators, such as polar bears and tigers.
He also works as the acting curator of paleontology and geology at the State Museum of Pennsylvania in Harrisburg. Jasinski began as a volunteer, and credits former curator Robert Sullivan with introducing him to a new
world of paleontological research.
Coming to Penn was the next step in his career, he says, since a Ph.D. is almost a requirement in the highly competitive field—and the chance to work with Dodson, one of the world’s experts in paleontology, was a big draw.
As for the discovery of C. wangi (named for Xiaoming Wang, curator at the Natural History Museum of Los Angeles County and a renowned expert on mammalian carnivores), Jasinski says it underscores the importance of amateur collectors.
“Anyone can go out there and take part in the scientific process, even if they don’t know the end result,” Jasinski says. “They’re still a part of it.”
And this discovery will allow researchers to better understand what the world was like 12 million years ago.
“It allows us to understand how that time period compares to today, and we can use that to understand how things have changed from that time period to today,” he says. “It also informs us on the evolution of these animals. … It has direct bearing on the dog of today andhow they became what they are now.”


Fossil Dog