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Friday, February 22, 2013

The Amazing Antilocaprid Artiodactyls

Time to learn another not-so-dark secret about me: I am entirely fascinated by the antilocaprids, better known as pronghorns. In the past, this family was rather huge, but sadly they are only survived by one species and five subspecies today: Antilocapra americana, the pronghorn antelope. Technically, the "surname" antelope is misleading, as pronghorns are not true antelope, a somewhat miscellaneous group in Bovidae. As mentioned earlier, there are five subspecies that are usually accepted (from O'Gara and Yoakum, 2004):

  • The Sonoran pronghorn, A. a. sonoriensis, native to Arizona and Sonora, Mexico. This pronghorn is endangered, estimated with 300 individuals left, a considerable boost from 2002 when there were only 14, but not much to be desired.
  • The peninsular pronghorn, A. a. peninsularis (they were not creative with names), also known as the Baja California pronghorn, for it (shockingly) being found in that narrow stretch of land. This subspecies is also sadly endangered, with ~200 left.
  • The Mexican pronghorn, A. a. mexicana is in addition to being found south of the border, can be found in the US as well. While under the IUCN, it falls under 'Conservation Dependent' it is luckily at lower risk and a gleam of hope for the species.
  • The Oregon pronghorn, A. a. oregona, found in Oregon, Idaho, Nevada, and California. This subspecies was actually first noted by Lewis and Clark (several Spanish explorers mentioned other subspecies prior, but these reports never made it much in the scientific world). They are almost indistinguishable genetically from other subspecies, probably hinting it as evolving recently if it indeed a separate subspecies.
  • The American pronghorn, A. a. americana, wielding a misleading name as all pronghorns are American and they always have been American ever since they first evolved. As with the Oregon pronghorn, their status as a separate subspecies is debated, but for this post, will remain separate.
The males are rather dashing.

And while these ungulates are rather odd compared to North America's cast of deer, bison, muskoxen, and peccaries today, the prehistoric forms actually delve into deeper vats of bizarreness. This is mainly due to their horns. Modern pronghorns have hatchet-shaped horns with prongs (the name suddenly makes complete sense). Prehistoric forms, probably as a result of a bet from a neighboring frat house, decided to go much more stranger with their horns and like people in the 80's, experimented with many different types.

Illingoceros, shown above, was one such pronghorn. Its horns resembled more of a modern markhor than they do their relatives today. Slightly larger than modern pronghorns, it completely lacked the characteristic hatchet horns. A cursory glance would almost lead one to believe it was a goat of some kind, or a fantastical unicorn. Shown below is Hayoceros, about the same size as Illingoceros, but with different headgear.

 Its horns more resemble the classic hatchet shape than the latter, but taking it to an extreme: two rather long horns jutting skyward, and a second pair with two prongs each jutting forward. The only ungulate today to naturally possess four horns is the Indian chousingha, or appropriately, the four-horned antelope. Would be a bad day for any predator who was stupid enough to corner this beast.

Above is Ramoceros, a small pronghorn relative that almost resembled a deer, especially from the perspective of the left one above. Also not much info on this one.

Aaaaaannnnndddd.......another one with barely any information on it. This antilocaprid, named Stockoceros also resembled a deer in some aspects.

Of course, pronghorns also experimented with size, like "pachyderms", moas, lizards, and other famous prehistoric creatures. Capromeryx was the ultimate byproduct of this, standing 2ft at the withers, almost half the height of modern-day pronghorns. It was extremely widespread, found in Texas, New Mexico, Nebraska, Kansas, and three Mexican states. Obviously it was doing something right.

From twisted horns to forked horns and hatchet horns and pygmies, the pronghorns have enjoyed a successful history for nearly 25 million years. But as touched on early, our only representative of this amazing family is dying out. Let's try and save it. Long live the antilocaprids.

None of the pictures provided belong to the author, except for the Illingoceros and Hayoceros, which were not illustrated by the author.

1 comment:

  1. Ilingoceros and Hayoceros were probably very fast pronghorns as well, and those horns quite interesting. Wonder how fast they were and if they had any true speed competition back then?