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Re: DINOSAUR digest 3468



--- dinosaur@usc.edu wrote:

> Subject: Re: Oviraptor=Parrot?
 
First: typical parrots are seed-eaters, not
fruit-eaters. Parrots concentrate on seed interior.
Frugivores eat soft parts of fruit and have different
adaptations.

> because the jaws seemed overly built
> for such delicate things as
> eggs. 

Animal the size of Oviraptor could break any eggshell
without special adaptations. 

> Indeed, two prongs in the top of the jaw,
> inset from the sides and formed
> from the maxillary bones where they fold beneath the
> vomer (which subsequent
> researchers would continue to refer to as "teeth").
> The problem, as shown even
> later by David Smith, was that what Osborn had
> pointed to as prongs in the
> holotype of *O. philoceratops* were in fact
> ectopterygoids. Be it so, Osborn
> would be borne out for identifying at least an
> animal suited to crushing
> shelled food. 

Nice, so predator theory is falling.
  
>   Along with the embryo, two tiny skulls Mickey
> previously mentioned of "baby"
> *Byronosaurus* (originally thought to be
> dromaeosaurids before an adult skull
> of *Byrosaurus* was recovered) were associated, and
> these were considered to
> pertain to food brought by the nesting parent to
> feed soon-to-hatch babies. 

Many birds are vegetarian as adults but feed animal
food to nestlings. 

For example, many finches and sparrows are
seed-eaters, but bring insects to nest. Asian
hornbills are fruit-eaters, but succesfully hunt small
animals to feed chicks.

> However, following Barsbold, we know that
> oviraptorids skulls, like turtles but
> unlike parrots, tend to the akinetic, without mobile
> snouts or palatal
> elements. 

If oviraptorids could manipulate food with their
hands, it would compensate for akinetic skull.

 
> unlikely that fruits were their preferred foods, as
> these do not tend to be
> ample foods on the ground, since parrots (for most
> of the African ones at
> least) are cliff or canopy dwellers who feed in the
> regions of fruit abundance
> -- in trees. 

Every seed must fall to the ground to germinate. So,
unless there was a niche of seed-eating pterosaurs,
oviraptorids could feed on ground or with limited
climbing.  

> Furthermore, it is hypothesized (Zweers et al) that
> the most primitive
> form of feeding in birds was a so-called
> 'catch-and-throw' method, in
> which a food item is grabbed and thrown into the air
> to be
> subsequently swallowed.  Maybe a similar method
> existed in advanced
> theropods such as oviraptors?

I always thought it is not phylogeny-related, but
common to long-billed birds with short tongues. No
need for throwing food if you have beak so short as
parrot or oviraptorid.
 
>>So when another
> biomech discussion rears its
> > "ugly" head, 

Why ugly? If I had trime to study dinosaurs I would be
biomechanist. There is no other way to learn how these
critters really lived, what they could do, would they
eat lawyers whole or just nibble pieces?... ;-)

> > Cheetahs have much more extreme cursorial
> adaptations, don't they? Plus, the
> > beak really looks all wrong for this...
> 
> Oviraptor has relatively short stocky legs for a
> coelurosaur of its size. It's on the dromaeosaurid
> end of things, not on
theavimimid-caenagnathid-troodontid-ornithomimid-tyrannosaurid
> part of the spectrum.
 
I was suggested by some reconstructions which show
unusually skinny, long-legged animal. Short beak would
increase biting force. But now seed-eating seems more
plausible.
 
Jerzy


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