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Seymour's egg shell conductance assumptions?



Seymour's (Seymour, R.S. 1979. Dinosaur eggs: gas conductance through the
shell, water loss during incubation and clutch size. Paleobiology
5(1):1-11) paper is often cited as evidence that dinosaur eggs were
incubated under conditions of high humidity.  The argument goes that a
certain pore area lets in an amount of oxygen which is proportional to
the water it lets out.  And since they needed alot of oxygen they needed
alot of pores which, because they also allowed water out, would have
dessivated the embryo unless oviposited in high humidity, i.e., deep sand,
or vegetation mound.
But, according to Ralph Ackerman in a Turtle Egg paper, "water and
respiratory exchange may not be coupled at the shell in contrast to the
gas exchange reported for the avian egg..."

And this suggests to me that pore area in dinosaurs might tell us nothing
about the relative amount of different gases let in or out of an extinct
species shell.  Any comments appreciated on or off line.
Thank you.
John Bois.