GRAY, Tenn. (WJHL) — The extinct species is called Borophagus, meaning “gluttonous eater” — and now researchers have learned the giant bone-crushing dog was present at the Pliocene-era Gray Fossil site.

The confirmation of a humerus (upper arm) bone of the species means the site is now confirmed to have had two species of “terrestrial apex predators,” or land animals atop the food chain, as well as alligators, another apex predator. The remains of at least one sabertooth cat also have been discovered at Gray.

Artist’s illustration of the ancient bone-crushing dog which was likely very similar to the Gray Fossil Site dog. Artwork by Mauricio Antón.

“With two large predators on land and alligators in the water, herbivores at the site would have had to be on high alert,” East Tennessee State University (ETSU) masters paleontology graduate Emily Bōgner said in a news release.

Bogner, currently a doctoral student at the University of California-Berkeley, and ETSU associate professor of geosciences Joshua Samuels conducted the research. The pair published a study on their findings in a recent Journal of Paleontology issue.

According to a Cambridge University Press article published July 25, the discovery marks “the first occurrence of this genus in a heavily forested ecosystem.”

Samuels said researchers hope to find additional evidence to tell them more about the species’ behavior and lifestyle at the site, which has different characteristics than most places in North America that Borophagus has been discovered. The 50 or so other sites where Borophagus has been discovered in the U.S. are typically grassland-dominated.

“Since the lifestyle of these dogs is thought to be similar to hyenas, I would also like to see bones that had been cracked open by Borophagus at the site,” Samuels said. “That could help us to understand what they were actually eating in the ancient Appalachian forests.”

Researchers estimate this specimen weighed in at between 115 and 160 pounds, a similar size to the largest wolves living today. The discovered bone has large areas where muscles once attached, making it likely that it was a powerful ambush hunter, whereas most wolves are pursuit predators.

The ambush hunting strategy of bone-crushing dogs might have been particularly well-suited for hunting large herbivores in the ancient forests of the Appalachian Mountains, researchers said. The presence of just one bone, so far at least, leaves many questions unanswered.

Emily Bōgner (left) and fellow student Julia Schap (right) during their time as graduate students in ETSU’s Paleontology Program. Photo from Josh Samuels.

“The limb proportions of Borophagus are a conundrum to researchers,” Bōgner said. “Having more limb bones would be a big help in understanding how these bone-crushing dogs moved.”

According to the Cambridge article, the specimen was estimated to be between 8 and 12 months old based on characteristics of the bone. It is located at ETSU’s Museum of Natural History.

The article also states that because of the Gray Fossil Site’s age “the conspicuous absence of Borophagus from the (site) was previously noted by multiple researchers.”