Re: Brontornis again

["Jaime A. Headden" <qilongia@yahoo.com>]

  Cristoph wrote:

<<So a bird would only need a jaw that is sufficient
to TAKE UP the food - this is why even large
vegetarian birds like ostriches and moas, only have
small heads: They don't need a larger head for their
kind of food.>>

  and Ron Orenstein wrote:

<Actually, this is untrue. There are quite a few
frugivorous and seed-eating birds with very strong
bills and large heads - any number of finches, for
example, or parrots.>

[snip]
 
<Of course the bill of a large macaw or cockatoo can
be a very powerful tool indeed; a hyacinth macaw can
break your arm without trouble.>

  Consider the size of the food item/s relative to the
body or head of the animal in question.

  Relatively small animals taking food items the size
of their heads or larger are going to have large
beaks, and the harder the food relative to the size of
the skull, the larger the aquisitive apparatus, and
the more strongly determined the device for rendering
the item for consumption (and pardon for the
tech-speak, but I'm coming out of a paper-writing
session, and well, some of you know how it is, but
this is the easiest way of saying it all --- just pull
out a dictionary if you have trouble :) ). But, the
size of the animal in question is close to six feet,
two meters, and this means, if it's head is between 1
and 1.5 feet long, or .28 and .32 meters, then hard
nuts and fruit rinds are not the item in question. For
this, a small skull and jaw would be sufficient to the
task, for the relative forces being exerted on the nut
would be so much more than a smaller nutivorous
animal, by exponents.

  I've seen the jaw of *Brontornis*, this "thunder
bird," and compared to something like *Andalgalornis*,
it is much more wide and with robust rims, suggesting
greater forces were applied to the sides than along
it, or at the tip, as in many birds of prey (hence the
narrow beaks). To me, Cristoph's suggestion of a
bone-cracker, as in hyenas, is more plausible than a
coconut-cracker.

  Additionally (here I go again), vultures do not
require such robust bone-breaker jaws because they do
not exert the cracking forces with their jaws in the
first place; king vultures and lammergeiers are the
most specialized bone-breakers, and both go about it
similarly. They either crack stones against the bone
(using tools, in the kings) or drop the bone from
great heights (as in the lammergeiers), to get at the
marrow. They are, by the way, quite successful at it.
This suggests similar innovation in other "smart"
tool-using creatures as sea otters, raccoons, crows
and many other passerines, etc.


=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
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