Resumen:
Pronghorn (Antilocapra americana) is the only member of the Antilocapridae family, and differs from bovids, cervids and other ruminants. It is found in North American deserts and grasslands (Fig. 1). Pronghorn is the second fastest land animal but can run for much longer than cheetah. Antilocapridae evolved in North America and were a successful family thanks to digestive and temperature regulation evolutions. These evolutions probably were a response to climate becoming highly seasonal about 34 million years ago, with glaciations alternating every 41-100 thousand years with temperatures slightly warmer than today, and millennial cycles of 2oC local cooling (Maslin, 2009). Lacking equivalent temperature regulation equus including horses came close to extinction (Mitchell and Lust, 2008; Kulemzina et al., 2014).