[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Horn Usage (was Re: Stateside Emus)



In a message dated 2/22/01 0:45:42 AM EST, NJPharris@aol.com writes:

>   The clue was something to the tune of "The only members of the deer family
>  in which both males and females have antlers are reindeer and these North
>  American relatives."

The answer of course would be "cabibou". Let's see if I can make this
post somewhere near relevant for the list.

Male caribou have much larger antlers than their female counterparts,
which they shed annually (I'm glad I spelled that last word correctly).
Although thei have defensive capabilities (mostly intraspecific combat),
their role is largely visual in nature. Large antlers impress females,
and can by visual means alone win fights with rivals (negating the need
to actually fight most of the time).

Female caribou, on the other hand, do not need visual displays. Their
antlers are more or less permanent, and much smaller. They use their
antlers to fight with other females long after the males have left the
herd. During the winter they need to protect what patches of food they
may find from other females in order for their growing offspring to eat.
Hence the female antlers served a more practical purpose, as opposed to
the flashy, over-the-top male antlers that are too expensive to maintain
and carry around all year long.

Perhaps this provides an analogue for the use of ceratopian horns? I'm
thinking that the smaller rostral horn (in conjunction with the beak) in
species such as Triceratops may have been for practical defense, while
the larger brow horns may have been mostly for show (but with some
degree of practicality). It would seem to be that the longer a horn is,
the greater degree of leverage they would have been subjected to at the
base during twisting or thrusting movements. A shorter, stouter horn, in
a more manoueverable position, would be far more practical. Perhaps the
large frill developed beyond the need for jaw muscle attachment into the
obscenely large thing it became in many species in order to provide a
counter-weight to help swing the tip of the snout about (with its stout
horn and sharp beak).

If Styracosaurus is a male form of Centrosaurus, then perhaps the
caribou analogy goes even further - both sexes having the practical
nasal horn, with only the males having the fancy-shmancy frill spikes to
impress the gals. It makes you wonder whether the dominant members of
some species (Styracosaurus, Torosaurus) had to be protected themselves
by the more practically built females from the attention of predators
(since I'm guessing they couldn't shed their sexual displays like
antlers).


-- 

____________________________________________________________

Dann Pigdon                   Australian Dinosaurs:
GIS Archaeologist           http://dannsdinosaurs.terrashare.com
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
____________________________________________________________