Chapter 1: The Pronghorn's Legacy

In the rugged terrains of the American West, a surprising remnant from the Pleistocene era still roams. If a sabertooth or a dire wolf were to chase after it, they would be long gone before their prey could even reach top speed. Yet, what sends shivers down their spines is the pronghorn, which scatters in alarm as a cheetah-like predator bursts into their midst.

The sleek feline, agile and built for speed like a greyhound, has singled out its target and, with laser-like focus, darts after it. The large cat lunges, aiming to catch her prey but only grazes the pronghorn's fur, sending wisps of hair spiraling down. The pronghorn, feeling the predator's hot breath, pushes itself to the limit, galloping at full speed, oblivious to everything but the impending danger. The feline has mere seconds of stamina left, but she is close! The pronghorn surges over a small rise and… vanishes.

In an instant, the predator finds herself tumbling into a treacherous pit cave, a fate shared by both the hunter and the hunted. This sudden plunge into darkness spares them from a protracted end, joining the many lives lost in this deep chasm, destined to be forgotten beneath layers of sediment.

Fast forward to today, and the only remnants of such chases are tales of the past. The cheetah, Acinonyx jubatus, stands as the reigning champion of speed, eclipsing all other land animals.

Common knowledge attributes the title of the fastest land creature to the cheetah, which can sprint at speeds between 109–120 km/h (68–75 mph). But who claims the title of the second fastest? Many might guess springboks or other African antelopes, but they would be mistaken. The pronghorn, or Antilocapra americana, native to North America, holds this impressive title, capable of running at 88.5 km/h (55 mph).

At first glance, it seems illogical for an animal to be equipped for such remarkable speed, especially when it can easily outpace any local predator. Bears? They can't keep up. Wolves? Not a chance. Pumas? Forget it. It appears evolutionarily counterintuitive for pronghorns to invest energy in speed when they already have the advantage. Animals typically stop evolving towards greater speed once they have a sufficient edge over their predators. So, what motivates the pronghorn?

The answer lies in the distant past, at the end of the last Ice Age, when the American cheetah, genus Miracinonyx, roamed the land. This period, which may seem far removed from today, is quite recent in the context of Earth's history. Until the extinction of the American cheetah, it seems that pronghorns and these big cats were engaged in an evolutionary arms race, each pushing the other toward greater speeds. In North America, the pronghorns that could outrun the cheetahs thrived and reproduced, passing down their speed-enhancing traits. Thus, the pronghorns' remarkable speed today can be traced back to their need to escape an ancient predator—essentially, they are still fleeing from ghosts.

How did cheetahs come to inhabit these regions? They didn't migrate from Africa; rather, the American cheetah is believed to be more closely related to modern cougars, having evolved similar traits due to similar environmental pressures.

This intriguing narrative remained largely theoretical until recently, when discoveries in Natural Trap Cave in Wyoming provided substantial evidence. Researchers uncovered American cheetah bones and conducted isotope analyses, revealing that these cats primarily preyed on pronghorns, while other predators at the site, like dire wolves and American lions, consumed far fewer.

I highly recommend watching the Paleotalks episode titled "Rappelling into the Pleistocene at Natural Trap Cave," which delves into this captivating research.

In this video, learn about the significant findings from Natural Trap Cave, including the relationship between pronghorns and the American cheetah.

While we can't measure the speed of a long-extinct cat, we know that Miracinonyx had two known species that inhabited various environments across North America, from the Appalachian mountains to the Grand Canyon. They were likely swift but adapted to diverse habitats.

In conclusion, the pronghorn's status as the second fastest land animal is a vestige of its ancient struggle against a fast, cheetah-like predator. Today, pronghorns thrive, able to outrun every threat in their environment, save for humans and their modern contraptions. With the extinction of their primary predator, the pronghorn emerged victorious in this age-old race.

In this video, explore what made the pronghorn so incredibly fast and how its evolutionary history shaped its adaptations.