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Re: Psittacosaurus adult found with 34 juveniles

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).

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.

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



Scott Hartman
Zoology & Physiology
University of Wyoming
Laramie, WY 82070

(307) 742-3799