Extinct and Extant Pronghorns, America’s Psuedo Antelopes

One species of pronghorn still races across the wilderness areas of the American west where along with bison they’re considered icons of the short grass prairie.  But during the Pleistocene and Pliocene, there were at least 14 species of pronghorns prancing the plains of North America from what is now Florida to California and from Mexico to Canada.

The only species of pronghorn still extant–Antilocapra americana.  Note just 2 prongs.  Some extinct species had 4 or even 6 prongs.

Every species of extant and extinct pronghorn required short grass prairie and/or scrub habitat.  Modern day pronghorns get skittish any time they’re near any trees, no matter how small the wooded area is.  They like to be able to see around them for great distances, so they can use their incredible running ability to keep considerable space between themselves and predators.  Pronghorns can run from 62-70 mph and can maintain top speed for long distances, enabling them to cover 5 miles in 5 minutes.  Many a disapointed group of pioneers went hungry after unsuccessfully stalking the wary fleet-footed mammals.  However, some learned an old Indian trick that took advantage of the creature’s overbearing sense of curiousity.  It’s possible to lure pronghorns to within gun shot range by flashing shiny objects at them.  Like just about every large mammal species, populations of pronghorns plummetted following European colonization, though with modern game management, they’ve rebounded to sustainable levels.

Pronghorns are (or in the case of the extinct species were) characterized by having horns with deciduous sheaths, and they have distinctive teeth and skull ridges.  They’re all browsers of shortgrass prairie plants, carefully picking the most nutritious plants from the available forbs growing among the grasses.   They originally evolved from Merycodonts which were a family of Miocene-age ungulates.  Pronghorns never crossed the Bering landbridge to Asia, unlike horses and camels, and they never penetrated into South America–probably because of their strict habitat requirements.  Some species lived in southeastern North America during the Pliocene and early Pleistocene, but they’ve been absent from the region since the mid-Pleistocene (for at least 1 million years) when the corridor of scrubland habitat became interdicted with woodlands, most likely along the Mississippi River.  This prevented recolonization of the region when habitat conditions may have again become more favorable.  By the late Pleistocene all remaining pronghorn species were restricted to western North America.  Some species are known from only a few specimens while others are represented by many fossils.  The following is a summary of all the species of pronghorns that paleontologists know lived in North America over the past 5 million years.

Prentices’s Pronghorn (Ceratomeryx prenticei)–a poorly known Pliocene species.

Mathew’s Pronghorn (Capromeryx furcifer)–a small 4-horned Pliocene-Late Pleistocene species that was 2/3rds the size of a modern day pronghorn.  It’s fossil remains come from California and Florida.

Skinner’s Pronghorn (Capromeryx arizonensis)–Lived from the Pliocene-Mid Pleistocene.  Specimens have been found in Arizona and Florida (Sante Fe, Inglis).

Diminutive Pronghorn (Capromeryx minor)–A late Pleistocene species that weighed just 20 lbs.  Bjorn Kurten believed it lived much like smaller African antelopes such as klipspringers which hide among rocks and shrubs.  Its remains have been found at Rancho La Brea and other western sites.  At Rancho La Brea it apparently was far more common than the modern day pronghorn which also lived in the region then.

Reconstructed skeleton of the Diminutive pronghorn (Capromeryx minor), an extinct species estimated to weigh ~20 lbs.

Mexican pronghorn (Capromeryx mexicana)–A late Pleistocene species found in Mexico that was about the same size as the diminutive pronghorn.

Schuler’s pronghorn (Tetrameryx shuleri)–A large 4 -horned pronghorn of uncertain age.  Its fossil remains have been found in Texas at the Dallas sandpit.

Skull of Schuler’s Pronghorn (Tetrameryx schuleri), an extinct 4-pronged species of pronghorn.  Fossil remains of this species come from the Dallas sandpit in Texas.

Irvington Pronghorn (Tetrameryx irvingtonensis)–A mid Pleistocene 4-horned species.  Same size as the modern pronghorn.

Knox’s pronghorn (Tetrameryx knoxensis)–Little is known about this species.

Mooser’s pronghorn (Tetramyrex mooser)–An early Pleistocene species found in central Mexico.  It was 4-horned.

Tacubaya pronghorn (Tetramyrex tacubayensis)–Another Mexican species with 4 horns.

Hay’s pronghorn (Hayoceros falkenbachi)–A 6 pronged species the same size as the modern day pronghorn.

Conkling’s pronghorn (Stockoceros conklingi)–It was stockier than the modern day pronghorn but was intermediate in size between that species and the diminutive pronghorn.  During the Pleistocene it roamed the mountains of Mexico and New Mexico and was adapted to rugged terrain.

Quentin’s pronghorn (Stockoceros onusrosagris)–A pleistocene species that lived in Arizona.  Slightly smaller than the modern pronghorn.

Garcia’s pronghorn (Antilocapra garcia)–A Pliocene species ancestral to the modern day pronghorn.  Its fossil remains come from Florida.

American Pronghorn (Antilocapra americana)–A Pleistocene and Holocene species.  The only surviving species of pronghorn.

Cheetahs and wolves preyed on pronghorns during the Pleistocene.  The former was the only animal fast enough to outrun them over short distances; packs of the latter could wear down pronghorns suffering from malnutrition or injury.

Reference:

Kurten, Bjorn

Pleistocene Mammals of North America

Columbia University Press 1980

Tags: Antilocapra american, Pronghorn, Stockoceros, the diminutive pronghorn