Breakable dino eggs

[Phillip Bigelow <n8010095@henson.cc.wwu.edu>]

> Neil Clark <NCLARK@museum.gla.ac.uk> wrote:
>> One thing that worries me is how the eggs are laid in the first place.  If 
>> the eggs are so thin it is likely that the parent would have to squat to 
>> lay (because if it were dropped from any height, it would break!).  If 
>> the dinosaur had to squat, it is difficult for it to produce regular lines 
>> of eggs without the tail breaking them.  Even more difficult for a 
>> sauropod, I imagine :-)  I believe they may have dug a hole, or 
>> trench?, and squatted over it to lay the eggs.  I'm just thinking aloud 
>> here, but I have trouble imagining how the eggs are physically laid.

and Crpntr@ix.netcom.com (Kenneth Carpenter) wrote:
> 
> I agree, it is a problem that I have not satisfied myself with.  
> However, we do know they did it.  They must have squatted, or 
> kneeled back on their haunches.  Also, crocs and turtles sometimes 
> cushion the fall of the eggs with their hind feet.
  

   Eyebrows very highly raised at this point...
 
I must be missing something.  I thought it was common knowledge amoungst egg
people that turtle eggs are some of the least calcified of the reptilia
eggs. 
Turtle eggs are leathery and elastic.  There are good reasons for this. 
Because turtle babies have high infant mortality, a lot of eggs are laid.
In order to pack as many eggs as possible into the mother's ovi-chamber,
elastic eggs produce a tighter "pack" than do highly calcified eggs.
Elastic, leathery eggs have two other benefits: they don't break when they
are dropped from the ovipositor into the sandy pit; and they have extremely
high gas permeability.  High gas permeability is important in any eggs that
are buried (as opposed to those eggs that are brooded, which are exposed to
surface air in an open nest).  Buried eggs have a much smaller air
circulation around them than are brooded eggs.
  The thin, 2mm-thick shell of ?T. bataar may indeed be illusory.  Perhaps
the majority of the thickness of the shell was composed of elastic soft
tissue. The calcite we see in the shell is what remains after the leathery
part rotted away. 
  Crocodyle eggs have a lot of calcification, but are slightly more elastic
than is a chicken egg. 

 We _still_ don't know much about how these T. bataar eggs were deposited.
Since Carpenter doesn't buy the body incubation route for large dinos., that
leaves vegatative fermentation as the incubation heat-source.  In order for
vegatatative fermentation to work effectively, the eggs must be buried.  Now,
although crocodyles don't use vegatative fermentation for incubation, they
_do_ bury their eggs. 
In such case, the dino-experts should abandon using birds as modern analogs,
and instead, use crocodylians as egg-laying models.  And Larry Martin will
be proud!