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Re: Dino sex and therm tally rant (and feather origins thrown in)



Bettyc wrote:
> jamolnar@juno.com wrote:

> > Yes.  Turtles, snakes, lizards, etc have rubbery-shelled eggs.  

There are some lizards, especially certain (but not all) geckos that lay
hard-shelled eggs. They are soft and sticky when first laid, but they
soon harden and often adhere to the surface they are deposited on. There
are also some lizards such as some (but not all) skinks that are
viviparous. Perhaps there was this kind of diversity among the
dinosaurs. 

>>  Are there fossil turtle eggs?
> Would we be sure if they were or were not turtle eggs if there were no 
> embryos?

There have been eggs attributed to tortoises found in the Oligocene
sediments of the White River Badlands of the American west. I saw one
specimen in a private collection that contained bones that were visible
in the broken end of the specimen, but I am doubtful if it was ever
studied to confirm that it was from a Chelonian. The abundance of
terrestrial tortoises in the same sediments as the eggs, especially
those of Stelemys nebraskensis, and the fact that the fossil eggs are
spherical (characteristic shape of Chelonian eggs) is probably why these
eggs are assumed to be from tortoises. I think I recall seeing photos of
snake and crocodilian eggs from the Tertiary somewhere in Europe. I'm
sure if some dinosaurs did lay soft, leathery eggs, they would fossilize
under the correct conditions. Are there any eggs known from any
non-dinosaurian Mesozoic (or even earlier) animals that may have been
soft shelled?   

-- 
Adam Black
Wildlife Art of the Tertiary & Pleistocene
paleoart@digital.net
Archer, Florida