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Re: Psittacosaurus adult found with 34 juveniles



The Psitticacosaur integument, on-line:

http://www.senckenberg.de/pdf/gmayr43.pdf

And mentioned in:
http://www-hsc.usc.edu/~cmchuong/2003JEZAdapt.pdf

I was picturing the psittacosaur integument, described as ?bristles?, as being similar to hedgehog bristles (spines): stiff, yet flexible. Or perhaps they are more similar to Beipiaosaurus, only longer and thicker. Unknown at this point.

Dann Pigdon wrote:
>Evan Robinson wrote:
>
> Although they might, the psittacosaurs presumably do not incubate their eggs
> by sitting on them...


Perhaps not by sitting ON them - but a bristled tail wrapped around
them? I'm thinking of how wolves and foxes use their tails as 'blankets'
during cold weather.

Interesting idea. A large female cobra wraps her body around her eggs and assists in egg incubation by flexing her muscles and vibrating. Of course the Cobra?s eggs have leathery shells.! ?


How about those Early Cretaceous Hypsilophodontids down your way in southeastern Australia? Do workers still think that a lack of LAG lines indicates an elevated metabolic rate? (They were in the Antarctic circle at the time). How do you suppose that they kept their eggs warm enough to hatch? Is there any eggshell associated with them? No response required if unknown.

From: DinoBoyGraphics@aol.com
In response to issues rised to by Evan Robinson:

>>>It is possible that they all came from the one parent, the eggs could have been mass shelled at the same time. The psittacosaurs may not have yet fully developed the more avian ovary system of shelling one egg at a time<<<

I think it is likely that the eggs were all shelled at one time. I only suspect that they cannot come
from one parent because they would have to be a tenth the size (if not substantially smaller) to fit
into the body cavity of an adult of the size that is (apparently) represented by the skull on top of >the nest. It seems less likely, though certainly possible, that precocial young would still be in the >nest after such a large amount of growth. I therefore think it more likely (though hardly air-tight) >that the young were born closer in size to the that represented by the preserved animals, and >they came from different mothers. If we find complete eggs, it will obviously be easier to answer >this question (because birth size will be constrained).

Good theory. I would even buy into semi-precocial psittacosaurs. They could have fairly large eggs, belonging to multiple females.


As for the rushing water making a hole around the animals hypothesis...maybe, but the fine->grained lithology argues against such a high-energy depositional environment. Also, while there is >no color change to easily indentify the nest surface, the animals do seem to be physically >interacting with (e.g. their bodies conform to) a nest-shaped depression.

I thought that maybe there was rushing from the way they were said to be holding their heads up. As you have said after seeing it live, this does look like a nest grouping, even from the photograph. If this is a nest, and there was no transport, shouldn?t there be some eggshell? Or is there?


Hope that clarifies what I know about the specimen, as well as what I don't know (lots, alas).

Cheers,

Scott

Thanks,

Evan Robinson

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