A doctoral student from Pennsylvania has confirmed that there was once a hyena-like dog that roamed North America 12 million years ago.

The fossil of the extinct species called Cynarctus wangi, was unearthed in Maryland and was described as a canine with massive jaws capable of crushing bone.

It belonged to subfamily Borophaginae that were endemic in North America for 33 million years and was classified as one of the top predators of their network during its time.

The borophaginae dogs evolved to eat bones from very large prey species. They became colossal creatures, the largest dogs the world has ever seen, naturalist Scottie Westfall noted.

The study's lead author, Steven E. Jasinski, a student in the Department of Earth and Environmental Science in Penn's School of Arts & Sciences, said these ancient dogs are believed to behave like the hyenas of today.

There are currently four known species of hyena today: the spotted hyena, the striped hyena, the brown hyena and the aardwolf. Hyenas are bold and intelligent hunters that have the ability to eat bones, teeth and even hooves. National Geographic describes spotted hyenas as "hardy beasts that are also skilled hunters that will take down wildebeest or antelope." Possessing sharp eyesight and hearing that can help them track their preys. They are also good runners and are able to run distances without wearing their selves out. 

Despite its strong jaws, the researchers believe C. wangi did not just feed on meat to survive but as well as plants and insects.

Initially, the researchers thought the fossil is just one of the commonly found fossils that belonged to species called marylandica, which had been found in older sediment in the same area. Further investigation led them to concluding that the specimen represented a distinct species new to science.

C. wangi represents the first known carnivore from the Choptank Formation in Maryland's Calvert Cliffs region.

The researchers claim that the fossil provides them with a glimpse of what prehistoric life was like on the land of North American's East Coast.

"Most fossils known from this time period represent marine animals, who become fossilized more easily than animals on land," Jasinski said in a statement. "It is quite rare we find fossils from land animals in this region during this time, but each one provides important information for what life was like then."