North America Used to Have its Very Own Hyena

Think of a hyena, and you'll probably picture a giggly beast loping across the east African savanna—or, if you’re really up on your mammalogy, one of the other three hyena species that roam Africa and the Middle East. But you could just as easily envision a hyena much closer to home, trotting around the rocky terrain of Arizona. That's right: For a time, America had its very own hyena.

The beast’s introduction to paleontologists began in 1901. That year, workmen at the Val Verde Copper Mines in Anita, Arizona were poking around nearby limestone exposures when they came across a wealth of broken fossil mammal bones. News of the find got out to paleontologist B.C. Bicknell, and the legendary fossil hunter Barnum Brown even came out from New York to pick up a few specimens in 1904. The haul included the remains of squirrels, pocket gophers, pronghorn, and what at first looked to be jaw fragments from a big cat.

However, for reasons unknown, no one rushed to describe the fossils. Eventually the bones made their way to what’s now the National Museum of Natural History, and it was there that paleontologist Oliver Perry Hay determined that the fossilized feline was really something else. The cusps and troughs of the preserved teeth—telltale clues for mammal paleontologists—allowed Hay to figure out the jaw had belonged to a hyena, the first and only species of its kind to make it to North America.

This was enough to give the extinct carnivore its own distinct title. Hay chose Chasmaporthetes ossifragus, writing: “The name of this [genus] makes allusion to the Grand Canyon, whose beginning this animal may have witnessed.” (New geologic estimates have pushed the formation of the Grand Canyon much further back in time, but the poetry still clings to the title.)

But how did the hyena get to North America, and how did it live?

After Hay’s initial description, Chasmaporthetes specimens of different species were found in Africa, Europe and Asia. These specimens track this hyena’s origin in the Old World before, sometime between 5 and 3 million years ago, it traveled over the Bering Land Bridge. From there, the beasts got as far south as northern Mexico and as far east as Florida.

Even though the American species was first to be named, Chasmaporthetes fossils found in Africa, Europe and Asia are more complete. According to Zhijie Jack Tseng, an expert on fossil carnivores at the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, only a few isolated teeth, skull fragments and limb bone pieces have been found. “I would say no more than 30 percent of the skeleton of Chasmaporthetes is known” from America, Tseng says.

Still, it’s enough to know that Chasmaporthetes really was a hyena that mingled with America’s ancient fauna. For a time, between 3 and 1.5 million years ago, hyenas coexisted with sabercats, bone-crushing dogs, mastodons, pronghorn and other mammals that made North America a mix of the strange and the familiar.

We know what Chasmaporthetes looked like mostly because of finds elsewhere. Compared to today’s spotted hyenas, fossils show, this extinct species was a bit smaller and lacked the hunched posture. Instead Chasmaporthetes had proportions more like a wolf, “with relatively elongated foot bones indicative of increased running capability compared to spotted hyenas,” Tseng says. In other words, this was a running hyena—even better-suited to chasing down prey over long distances than even today’s spotted hyena is.

And much like its modern relatives, Chasmaporthetes had an impressive bite. “A study of skull mechanics by my Spanish colleagues and I demonstrated that the skull of Chasmaporthetes was just as capable of handling bone-cracking forces as spotted hyenas,” Tseng says. Chasmaporthetes may have crunched bone less often than modern hyenas because of its smaller size, but it nevertheless was capable of turning a carcass to splinters.

Chasmaporthetes wasn’t the only carnivore capable of such feats during its heyday. The continent was also home to wild dogs capable of running down prey and busting bones. “Hyenas and canids seem to have had a multi-million year competition for dominance,” Tseng says, “and dogs were ultimately victorious.” Exactly why the hyenas died back, though, is a mystery. It may be that the dogs were simply more adept at catching prey, outcompeting Chasmaporthetes.

The very last of their kind seem to come from the 1 million year old deposits of El Golfo, Mexico, on the southern part of their range. This may have been a last refuge from the wolves that made their way back into North America and were chasing down the same prey.

Still, the hyena had a good run. The geographic span of Chasmaporthetes fossils from Africa to Europe to Asia to North America “makes them one of the most widespread carnivorans of all time, only dwarfed by canids such as the red fox,” Tseng says. And there may be much more of them yet to find. “The fact that all Chasmaporthetes fossils in North America are found in the southern U.S. and northern Mexico is likely a result of a big geographic gap in the hyena fossil record,” Tseng says. The hyenas must have ran across through the Pacific Northwest and the Great Plains to reach their haunts throughout North America.

“It really is a shame they are extinct,” Tseng says, “because I would love to see a globally distributed hyena living today.” Time will tell. Perhaps, if today’s hyenas survive the Sixth Extinction our species are intent on creating, they could spread across the continents at some future time. Imagine that for a moment, standing on the North Rim of the Grand Canyon to hear the eerie whoops and giggles of hyenas returning to claim the southwest once more.

Riley Black | | READ MORE

Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Scientific American.