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Re: Cheekless and lipless dinosaurs...



Birds have no cheeks or lips and have absolutely no problem drinking
water.
Neither do crocodiles, snakes, turtles, or lizards.  Of the groups that
flank Dinosuaria (birds and crocs) none have lips or cheeks.

Of the dinosauria we have SEVERAL species that are known to have been
beaked.  Stegosaurs, ceratopsians, hadrosaurs, oviaptors were all
beaked.
I've been told that the AMNH has a life size set of skulls (ceratopian
and another) that are mechanical and show how the teeth meet to chew
very efficiently WITHOUT THE NEED for fleshy cheeks.  It's even been
proposed that the tiny holes on the head of T rex were possibly where a
beak-like piece went on.

Dinosaurs do not have the range of motion to chew as a mammal does. 
They can't roll the jaw from side to side -say in the typical
cud-chewing motion of a cow.  Dinosaurs could ONLY go up and down, so
teeth were staggered along the jaw to keep food in place to be chewed. 
They didn't NEED lips and cheeks like us loose-faced mammals to keep
from spitting out our food.

Larry's right-you're being mammal-centric

-Betty Cunningham

Christopher Srnka wrote:
> Just read an article in my local newspaper about a paper presented in
> Utah by Larry Witmer, an anatomist at Ohio University. According to the
> article, Witmer claims carnivorous dinos didn't have lips, but rather
> scales covering the teeth, as in modern lizards. He also says "We have a
> very mammalized view of the world. We're mammals, and we have cheeks,
> and cows and sheep and horses have cheeks. And so we see dinosaurs as
> being very similar to that. But today we have herbivorous reptiles and
> birds, and none of these guys have cheeks." The article goes on to say
> that Witmer feels that herbivorous dinos had extended beaks, like eagles
> or turtles, and there is an accompanying illustration of a Leptoceratops
> depicting a very odd-looking beak on the dino. Because of the lack of
> "cheeks" in the illustration, the dino appears to be grinning, and the
> beak covers the whole of the lower jaw and portions of the upper jaw.
>     Has anyone else heard about this paper (apparently it was just
> presented yesterday)? Witmer claims that the scientists he has explained
> this to have been "very convinced".
>    Wouldn't the lack of cheeks present some problems in drinking water,
> among other things?
> -Chris Srnka