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Re: Egg sizes



>On Wed, 5 Nov 1997, Dann Pigdon wrote:
>
>       Since all eggs need oxygen to survive, I would suspect that the
> diffusive efficiency of any type of egg shell could only be stretched 
> to a certain limit, beyond which the surface area:volume ratio would be
> insufficient. 

Right, but couldn't elongation of the egg increase the surface to volume
ratio? Perhaps this design was used to allowable extremes.

> As far as hard shelled eggs go, the larger the egg
> the thicker the shell needed to prevent it from being too fragile.

Unless the porosity was able to keep up with the thickness of the shell.
The shell needs to be an "exoskeleton" of sorts, but also needs to supply
diffusion space between the air outside of the shell and the amnion. 

> Could this be why most dinosaur pubic openings were suspiciously small,
> relative to body size that is?

Could be - good point.  Clutches may have been the rule.  It would seem to
me to make more sense if the hatchling's sizes were somehow proportionate
to those of the parent, if parental care was involved.  Generally
speaking, the larger the critter that exhibits parental care, the fewer
and large the expected live offspring (I think that this is true).

>       The largest modern (well, almost) bird egg I can think of
> would be the Madagascan elephant bird. Although it is extinct the eggs
> are occationally found buried in sand dunes, which was apparently
> how they were incubated. It would be interesting to know whether any
> dinosaur eggs are known to excede this egg size.

Yep, and if there were none that did, what does that say about parental
care, etc.  

Matt

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Matt Fraser
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