While driving the National Bison Range, I found several small groups of Pronghorn Antelope (Antilocapra americana), some at very close range. Here are a few images I made of these mammals:
Pronghorn are not really antelope, but in a family by itself (Antilocapridae). But the name has stuck with them.
Per Wikipedia, each “horn” of the pronghorn is composed of a slender, laterally flattened blade of bone that grows from the frontal bones of the skull, forming a permanent core. Skin covers the bony cores, but in the pronghorn it develops into a sheath of keratin, which is shed and regrown on an annual basis. Unlike the horns of many mammals, the horn sheaths of the pronghorn are branched, each sheath possessing a forward-pointing tine (hence the name pronghorn). The horns of males are well developed.
The pronghorn can run exceptionally fast, being built for maximum predator evasion through running, and is generally accepted to be the fastest land mammal in the Western Hemisphere. The top speed is very hard to measure accurately and varies between individuals; studies indicate it can run 35 mph for 4 mi (56 km/h for 6 km), 42 mph for 1 mi (67 km/h for 1.6 km); and 55 mph for .5 mi (88.5 km/h for .8 km). An impressive beast!