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Nature's pterosaurs


What I found to be of interest in these 2 papers was the following. In
the Argentinian egg the shell was calcified,and structurally similar to a
modern bird egg, but thinner. In the fossil from China the shell was
described as leathery. This is much more in line with the eggs of modern

If it is valid to assume both specimens are pterosaurs and therefore
related, how significant does this difference become. There have been
numerous studies on the physiology of Ca and the proteins in avian
eggshells, not as much on why reptile shells are different. The
assumption has been that the leathery condition is basal and the
calcified shell derived. There reports put both systems in the same group
with all the implications of metabolism of Ca, vitamin D, and the
included proteins. There would also be mechanical and behavioral
differences associated with the hatching process. Astonishing!



Alan H Brush
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Mystic, CT. 06355
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