Re: Shell-Shocked

[Dann Pigdon <dannj@alphalink.com.au>]

Rob Meyerson wrote:
> 
> Is it possible that, by developing hard-shelled eggs, the protodinosaurs 
> gained the advantage they needed to dominate the planet (a hard shelled egg 
> is harder for a nest robber)?

One advantage of hard shelled eggs is that they allow an adult animal to
incubate them directly. Sitting on a soft shelled egg does not sound like such a
good idea to me. Hard shelled eggs can also be moved about, whereas soft shelled
eggs must remain in the same position or else the embryo dies (when eggs are
collected in the wild they usually have a dot of ink placed on top of them to
indicate their orientation). Perhaps there is also a size factor: hard shelled
eggs can be bigger than soft shelled varieties.

So either dinosaurs developed hard shelled eggs to aid in direct incubation
(with small warm-blooded early dinosaurs sitting on them), or it was an
adaptation to allow larger egg sizes. I wonder how the varanid Megalania handled
things? Would it have layed many small eggs? Could it have been vivaporous?
Otherwise the size-based theory goes out the window.

-- 
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        Dann Pigdon
        GIS Archaeologist
        Melbourne, Australia

        Australian Dinosaurs:
        http://www.geocities.com/capecanaveral/4459/
        http://www.alphalink.com.au/~dannj
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