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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
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.
Whereas the bovid page
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.
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. :-)