And it can comfortably cruise at 30 mph for up to five miles before slowing. Even young pronghorns just a few hours old can, if necessary, run up to 45 mph. Millions of years ago, the pronghorn developed speed to escape fierce Pleistocene predators like the dire wolf and prehistoric cheetah. But reports of pronghorns racing horsemen and even automobiles seem to suggest that maybe the pronghorn also races just for the sheer joy of it. Oxygen-and the special ability to process lots of it.
Pronghorns consume three times the oxygen of similarly-sized animals.
An oversized trachea or windpipe, huge lungs, and a large heart give the pronghorn the ability to consume large amounts of oxygen. Even pronghorn muscle cells are packed with mitochondria, allowing them to burn more oxygen. Pronghorns also run with their mouths open-not because they are tired, as many assume, but because it allows the animals to take in more air. In addition, pronghorn hooves are padded to minimize shock, and their leg bones are extremely powerful. Pronghorns are an ancient species dating back nearly 20 million years-the only survivor of a group of hoofed mammals that originated in North America, and one of the few living links with the Ice Age.