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Re: Sheesh



----- Original Message -----
From: "K and T Dykes" <ktdykes@arcor.de>
Sent: Tuesday, October 24, 2006 9:32 PM

Why have no birds, or indeed -as far as is known- archosaurs (sensu sort of
traditional) never got around to giving birth to live young (sensu any way
anybody chooses)? [...]
My suspicion is that the hard and potentially sharp eggshell shards may be a
discouragement, but it's no more than a suspicion.

This could obviously be solved by evolving a soft shell (and then abandoning it altogether). The textbook explanation (...assuming there really is a textbook that mentions this question!) is that because archosaurs store the calcium the embryo needs in the shell and not in the yolk, the hard shell can't be abandoned, but I have no idea how testable this really is. It certainly sounds neat, however.