Re: Viviparous dinosaurs? and egg sites.

[Shaun Sinclair <ssinclai@gpu.srv.ualberta.ca>]

On Tue, 7 Feb 1995, Skip Dahlgren wrote:

> In regard to the question of T. rex eggs and the vast size difference between 
> hatchling (dare I say "chick"?) and adult, is it possible that either they 
> laid larger eggs than those which have been found, or that they bore live 
> young instead?  The latter would certainly be advantageous to a large 
> carnivore, whether social or solitary, whether it gave maternal care or not, 
> since such young most likely would not require a nest or shelter for any 
> significant period of time after birth, and would be better able to travel 
> and feed themselves (or keep up with their mother/family group).  Is there 
> any evidence to support such a hypothesis, and regarding which species?  Any 
> info would be appreciated.  :)
> 

        I would think that live birth would be more advantageous for the 
herbivores. In modern mammals, the carnivorous animals tend to have 
"nesting" behavior (ie. the give birth in a den, etc.), and care for 
their young for long periods of time (at least until the next breeding 
season). This is because of the need to teach the young the skills needed 
for survival. The herbivores, on the other hand, tend to drop their young 
"on the run" as it were. The young are required to get up and start moving 
almost immediately or are abandoned (in many cases). They are also 
required to become independent much more quickly.


        It is interesting that the eggs previously attributed to 
herbivorous dinosaurs are now being attributed to carnivorous ones. To 
what extent is this the case? Is it just with a few sites, or is this a 
broader rethinking? Are their any references out there for further 
reading on this?

        One last question...Is the attribution of an egg site to either 
of a carnivorous or herbivorous dinosaur based on the lay-out of the eggs 
and nest? I seem to recall Horner's egg mountain site being raised mounds 
with central depressions in which the eggs were arranged in concentric 
circles. I believe that this is also the layout for the "Devil's Coulee" 
egg site, and possibly for the Mongolian egg sites as well. If I am not 
mistaken, these sites are all attributable (and verified by embryos) as 
being herbivores. Is the linear pattern described in earlier posts being 
attributed to carnivors based on this difference in layout or is there 
more here?

Shaun
ssinclai@gpu.srv.ualberta.ca