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Re: Big = Old = Advanced?




On Mon, 1 Sep 1997, Bettyc wrote:

> Couldn't a larger species (than either emus or ostriches) afford
> to carry the eggs till the eggs where in a very developed state, then
> lay them with a very short incubation period?  Birds don't do this
> because birds fly and even the ones that don't would still have the
> mechanism to keep weight off the body by laying eggs at the earliest
> possible time in the development cycle.  Why would dinosaurs need this
> mechanism in the first place?  They never flew (DinoGeorge not
> withstanding-dinosaurs were laying eggs before they <possibly> became
> arborial)

I think this is unlikely at least for large non-avian dinosaurs.  Firstly,
there was an oviraptor fossil (I have ref. if needed) which showed that
their eggs were made very similarly to birds, i.e., the eggs are made,
laid, made, laid serially and not , like turtles, all at once.
Yes, that is only one dino.  But there are good reasons why this is
unlikely for all.  If all dinosaurs eggs were shelled, I wouldn't
think they could survive the jiggling that goes along with sprinting away
from predators etc.  Also, bigger eggs come up against a surface
area/volume problem.  Big eggs gotta breathe fresh air.  At least I think
this is true.  But don't some sharks do something like this?  

> eh nope-genetically this doesn't make sense.  It takes the same parts to
> make a chimp as a human, or nearly 98% identical parts.

2% of genes can equal more than 2% of parts.  A single regulatory gene,
for example, can lead to a whole suite of different characteristics.
Also, chimps are much more related to humans than birds (for example) are
to turtles.