The more we think we know, the more foolish we really are. And foolish, or at least impetuous, might be the best way to describe our understanding of North America’s fastest land mammal: the pronghorn.
There was a time in the 1990s when scientists who study extinct animals began to spin a tale about why pronghorn are so dang fast; 60 mph fast. That speed seemed such a waste. Wolves top out in the 30s and coyotes creep into maybe the low 40s, so wouldn’t the high 40s be sufficient for speed goats? Why generate all that excess speed if there hadn’t been a predator fast enough to necessitate it?
The extinct, high-speed predator theory quickly went viral, or as close to viral as an arcane scientific theory could back in those pre-internet days. The theory was helped along by journalists and science writers — dudes like me — who found the extinct-speedsters narrative compelling. The idea that modern pronghorn — the last of nearly 20 species from the family Antilocapridae — were running from ghosts made it even more poignant.
America once had cheetahs, we learned, as well as long-legged hyenas and even short-faced bears with limbs almost as tall as one of the ancient North American humans who arrived on the continent via Beringia, the land bridge that connected Asia with North America during the Pleistocene ice age.
I might be exaggerating about the legs on those ancient bears, but not by much. Spud Webb would have had to jump to look one of those beasts in the eye so long as it remained on all fours. And Webb would have had to climb onto the shoulders of Shaquille O’Neal to get a good look at that cave bear’s belly button if it stood upright.
So, I’m not trying to suggest those extinct speedsters were all a hoax. Surely, Miracinonyx, the North American cheetah that was more of a long-legged puma, gave pronghorn a good reason for their haste. But Miracinonyx probably wasn’t as fast as modern cheetahs, and the high-speed arms race between the extinct North American cats and pronghorn may not have been as closely contested as thought.
Maybe that doesn’t matter. I watched a video the other day of a pack of young wolves hunting a pair of pronghorn, and dang if they didn’t almost catch one.
The hunt was on a hillside in Greater Yellowstone, on an edge between open sagebrush and timber. The wolves used that terrain to their advantage as they tried to pin down dinner.
Speed, in this case, wasn’t the deciding factor, until it was.
Near the end of the wolves’ pursuit, when I thought I was about to see something I didn’t think possible — a wolf bringing down a sprinting pronghorn — that speed goat kicked on its afterburners. Suddenly, it was as if the wolf was on a leisurely walk and no longer doing its best imitation of Usain Bolt winning gold. While most of the chase had been at speeds far below what the pronghorn could do, that burst at the end saved the animal’s life.
That pronghorn didn’t have to run 60 mph because a predator that ran 55 mph was hot on its heels. It had to run 60 mph because a pack of 30-mph wolves was closing in on a speed goat hemmed in by the hungry pack and timber that didn’t offer the easiest escape route.
The best theory of the case now is that Miracinonyx probably evolved from pumas, rather than African cheetahs evolving from Miracinonyx. And Miracinonyx wasn’t necessarily the pronghorn-specializing hunter the extinct-speedster theory suggested. But Miracinonyx was likely faster than anything pronghorn encountered on the ancient plains of North America, and like that pronghorn in the video that needed a turbo burst to escape those opportunistic wolves, 60 mph ain’t a bad trick when you need it.