GRAY, Tenn. (WJHL) — Millions of years ago, ancient creatures known only by the remnants left behind roamed what we now know as the Tri-Cities, and researchers continue to uncover fossilized remains at the Gray Fossil Site that help paint an idea of what life looked like before modern-day humans.
The region is home now to black bears, deer, bobcats and plenty of smaller creatures such as squirrels, various bird species and opossums — but what did wildlife look like 4.5 to 5 million years ago during the early Pliocene epoch? And what predators were at the top of the food chain?
With the recent discovery of bones that belonged to an extinct genus called Borophagus — a giant bone-crushing dog — News Channel 11 set out to learn more about the lost life that lived on the land that would later become Northeast Tennessee.
Dr. Joshua Samuels works as an assistant professor of geosciences at East Tennesee State University and a research curator at the National History Museum and Gray Fossil Site. He studies the evolution of mammals — primarily rodents and carnivorans — and interactions among ancient animals.
“Many animals at the site are different from what lives here today, but their anatomy suggests they were well-suited for life in the ancient forests of the Appalachians,” Samuels said. “Many of the animals are adapted for climbing and feeding on forest plants. That agrees with evidence from fossil plants at the site, which suggests oak-hickory-pine forests were present here 5 million years ago.”
The scientist revealed that the fossils found at the Gray Fossil Site are thanks to a prehistoric sinkhole lake discovered by Tennessee Department of Transportation (TDOT) workers in May of 2000 during construction.
Borophagus remained at the top of the food chain alongside several other primitive predators, including sabertooth cats and alligators, according to Samuels. The sabertooth cat remains unidentified as only a few fragments of its skeleton have been found, according to Samuels, who also revealed the ancient dog has been confirmed by a single specimen as well.
“The bone-crushing dog is estimated to have weighed between 115 and 160 lbs., the sabertooth cat almost certainly weighed over 200 lbs., and the alligators were quite similar to their living relatives,” Samuels said. “The wolverine may have weighed as much as 60 lbs.”
Samuels said aside from the larger predators, ancient Appalachia hosted an ecosystem of carnivores of all sizes, including wolverines (Gulo sudorus), hawks, owls and plenty of snakes.
“There are also some other animals that would serve as predators, but they are better thought of as omnivores (eating plants and animals), like the bear (Plionarctos sp.), red panda (Pristinailurus bristoli), and badger (Arctomeles dimolodontus),” Samuels said in a written statement.
The most common predator in the Gray Fossil Site is the ancient alligator, which likely lived in the sinkhole lake that would later preserve the fossils. On the other side of the food chain, tapirs — which look similar to pigs but with a trunk — are the most common remains found at the site. Researchers believe the herbivores were a popular meal for the predators.
Samuels deemed the sabertooth cat as the most dangerous predator, but if the bone-crushing dogs hunted in packs as do wolves today, the Borophagus would have posed the biggest threat to prehistoric prey.
“Other herbivores like peccaries, camels, horses, and relatives of deer would also be likely prey,” Samuels said. “The biggest animals at Gray, mastodons and rhinos, would probably not be common prey for these predators but may have been scavenged.
“Wolverines are known to kill animals much larger than themselves (like deer), but more often feed on carrion and smaller mammals like rabbits. The red pandas probably fed on a mix of small animal prey and plant matter (fruit and seeds). Each of the predators would be considered an ambush hunter, meaning they would pounce on prey from cover. That makes sense given the plant fossils at the site point to a forest environment with lots of understory vegetation (lots of places to hide).”
The wide array of findings at the Gray Fossil Site belonged to creatures that lived alongside one another several million years ago, according to Samuels. Climate changes over time led some of the ancient animals to relocate to more suitable living conditions. Others died out.
“The extinction of many animals at Gray is probably a consequence of climate and habitat changes over time,” Samuels said. “The time period preserved at Gray 5 – 4.5 million years ago is prior to the start of the Pleistocene Ice Ages, which resulted in colder and drier conditions all over North America.
“As conditions changed, animals that adapted to those changes thrived, while others either became extinct or live in other places today (like alligators in the Southeast United States or wolverines in northern habitats). Many large animals, like mastodons, became extinct at the end of the last ice age, which coincided with a warmer climate and the spread of humans in North America.”
However, a handful of fossilized species at the Gray Fossil Site have descendants that remain in Northeast Tennessee. These include beavers, squirrels, chipmunks, moles, shrews, bats, turtles and frogs. To learn more about the continuing discoveries at the site, click here. For a complete list of animals, plants, fungi and algae found at the Gray Fossil Site, click here.