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RE: Velociraptor scavenged azhdarchid pterosaur



On Tue, Mar 6th, 2012 at 11:43 AM, Jaime Headden <qi_leong@hotmail.com> wrote:

> While I would like to echo Dann's comments regarding assumptions of diet in a 
> "typical herbivore"
> such as *Protoceratops andrewsi*, I'd like to note that the general arguments 
> for rendering it a
> herbivore are both traditional and compelling. There really isn't that much 
> that tells us that
> protoceratopsids like *andrewsi* _didn't_ dominate their diet with plants of 
> some sort. I _like_
> the idea of a omnivore for it, but the reasoning here is actually pretty weak 
> as it is based
> largely on the invocation of not assuming diet due to plasticity in diet of 
> living so-called
> "herbivores," especially pigs and ruminants.
> 
>   Just as we should never assume a *Tyrannosaurus rex* is not a strict 
> carnivore (and few
> scientists have done so), we should not assume any typical "herbivore" is 
> one, including
> hadrosaurids. But just as with hadrosaurids, there are more compelling 
> reasons to claim they 
were
> primarily herbivores that no matter how much of their diet was sprinkled with 
> eggs or grubs or
> small multituberculates, a Djadokhtan protoceratopsid probably _did_ prefer 
> plants to meat. And
> just as a tyrannosaur wouldn't turn its nose down to a free, weakly guarded 
> carcass, I doubt a
> Djadokhtan protoceratopsid would turn its beak down at a free egg or carcass. 
> There's a lot to
> say on the issue of any consumer to not get shoe-horned into strict herbivory 
> or strict
> carnivory, but also not to presume that omnivory, if possible, was likely and 
> that the animal
> would be a generalist.

Well said (or typed, as the case may be).

There are however some features of Protoceratops that would seem to indicate 
something other 
than strict herbivory was practiced.

The hooked and narrow beak is more reminscent of a bird of prey than that of 
any avian herbivore. 
Those prominent 'canine' teeth immediately behind the beak are also somewhat 
reminiscent of a 
tomial tooth.

Hadrosaurs almost scream 'herbivore' with their expanded tips of the jaws and 
batteries of grinding 
teeth, however the very narrow and deep beak of Protoceratops, combined with 
teeth that seem to 
have had more of a shearing than grinding action, would seem to suggest they 
were not mass-
guzzlers of plant matter in the manner of modern grazers. That doesn't preclude 
them being fussy 
browsers like antelope though.

The forward-facing eyes with what appears to be an excellant degree of 
binocular vision is also not 
what you would usually expect from a strict herbivore. Although if the main 
line of defense amongst 
ceratopsians was the powerful beak, then foward-facing eyes might have 
facilitated defensive 
lunging (behaviour that may have increased the likelihood of the horns of later 
ceratopsians being 
selected for). Then again, an ability and an inclination to rend flesh can be 
useful for both defense 
against predators, or for occasionally playing predator (or scavenger) yourself.

Protoceratops is sometimes known as 'the sheep of the Cretaceous', but perhaps 
they were more 
like Cretaceous suids? It's a pity that stomach contents haven't been found for 
them (as far as I'm 
aware).

-- 
_____________________________________________________________

Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
_____________________________________________________________