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Re: Bovids vs. Antilocaprids (resend)



Now in contrasting the differences between
Bovidae and Antilocapridae the only really useful
charachteristic is the shedding of the keratin sheath
on the horns. Can paleontologists tell by looking at
fossils if the sheath was shed or not?

I don't know. But I think it doesn't matter. The info comes from http://animaldiversity.ummz.umich.edu/site/accounts/information/Antilocapridae.html, which says:



Their most distinctive feature is their horns, which are like those of bovids in that they consist of a keratinous sheath over a bony core, but differ because the keratinous sheath is shed periodically (annually in males, irregularly in females). These horns are erect and consist of two branches or prongs, a short branch extending forward and located around halfway up the horn, and a longer, backwardly directed tip.

The skulls of pronghorns are also distinctive. They lack a sagittal crest. A complete postorbital bar is present, and the orbits are large and placed far back on the skull, behind the level of the last molar. A vacuity (space) separates the nasal from the lacrimal on each side of the rostrum. The lacrimal canal is inside the orbit and has a single opening.
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Whereas the bovid page http://animaldiversity.ummz.umich.edu/site/accounts/information/Bovidae.html says:


The skulls of members of this family lack sagittal crests. A postorbital bar defines the rear of the orbit. The lacrimal canals of bovids have a single opening, and it lies within the orbit. Pits in front of the orbits, called preorbital vacuities, are often present.
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So shame on the authors for not telling autapomorphies apart from plesiomorphies, but if you ever find an artiodactyl skull with a would-be antorbital fenestra (?!?), regard it as a pronghorn.

Perhaps most importantly, I don't think there's any reason to regard the lists copied above as exhaustive!!!

Forward this at will. :-)