The American pronghorn is an Ice Age animal that has survived a mass extinction event that wiped out most of its contemporaries.
The Pleistocene epoch is a series of Ice Ages occurred on Earth beginning about 2.4 million years ago until about 11,500 years ago. Global temperatures intermittently dropped very low, with periods of high temperatures in between.
Megafauna, or large animals like mammoths and giant sloths, existed during the Ice Age and went extinct during the late Pleistocene. Scientists aren't sure yet what caused the extinction of so many species within the same time period. It may be because of the extreme fluctuations in temperature, human intervention, or invasions of flora. It may be a combination of all these.
One Ice Age animal managed to outlast many of these megafauna. The pronghorn, which came into existence about 30,000 years ago, still roams certain places in the United States and Mexico. Interestingly, the pronghorn has mostly not changed since it first evolved tens of thousands of years ago. This is intriguing, since many large predators shrunk in size in order to adapt to changes in their environment. Scientists now want to know how the herbivorous pronghorn managed to live through a mass extinction event.
There had been two kinds of pronghorns—the smaller dwarf pronghorn, and the larger pronghorn that exists today. The dwarf pronghorn had gone extinct, which had puzzled scientists. Smaller animals had a better chance of surviving the extinction event, yet the dwarf pronghorn had died out.
Scientists now think that the failure of various plants to adapt led to the death of the dwarf pronghorn. Plants failed to grow, and the dwarf pronghorn wasn't able to find enough tree cover to hide from predators. The landscape of their habitat turned into open, grassy fields.
This change may have contributed to the survival of the larger pronghorn. Because they lived in flat grasslands, predators had nowhere to hide. Pronghorns were thus able to live in relative safety. With the extinction of their smaller relatives, they also had less competition.
In spite of managing to survive a mass extinction event and drastic changes in climate, pronghorns may not survive these present times. This Ice Age animal now faces what could be an even bigger threat to their species: humans.
There are five subspecies of pronghorns that still live in the US and Mexico. Three of these species—the sonoran, the peninsular pronghorn, and the Mexicana pronghorn—are endangered. Pronghorns also once roamed in Southern California, but humans had hunted that group to extinction. Their habitat also experienced destruction at the hands of humans.
About 700,000 pronghorns exist today, but these populations are in decline. However, zoos in both the US and Mexico are hard at work at saving wild pronghorns and their subspecies. The zoos are hand-rearing pronghorn fawns in Mexico, then transporting them to California to grow into adulthood.
It may take decades before the pronghorn population thrives again, but there is hope. Perhaps this Ice Age animal can survive yet another change in climate.
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