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Re: A note on pterosaur nesting behavior

Mike Habib wrote:

> are living bats that dig and scramble around on the ground, so  
> membrane wings are not as much a hazard as it might seem.

Bats that dig? Not aware of that. Even so, the key word here is "in" as in 
tunneling to the surface vs. "on". 

> > While all fossils are buried, the indications of the present three  
> > embryos do not indicate intentional burial.
> How so?

Flooding and vulcanism buried the three known eggs. 
> > If buried, evidently pterosaurs buried their eggs one at a time.
> This could be the case, but why do you think that need be true?

Mike, I'm arguing AGAINST the burial. I'm arguing that it need NOT be true. 
All present pterosaur eggs are singletons. IF they were intentionally buried, 
then these three, all distinct and widely separated taxa, were buried alone. 
That's a lot of work for one egg. Modern analogies? I can't think of any.
> > If lepidosaurs, the eggs could have been laid within a short time of  
> > hatching, which is the present indication.
> Life history variables are often quite plastic; 

Insert "over-generalization"  Let's stay specific.

I would hypothesize  
> that a short incubation time would be possible for many potential  
> phylogenetic positions.  Some birds have quite short incubation  
> times.  

And do they hatch ready to fly? No. 

Lepidosaurs take it even further, of course, with ovi- 
> viviparity and the like, but I would argue that the possible  
> incubation and nesting parameters has more to do with egg structure  
> and physiology than phylogenetic position (except to the the extent  
> that egg morphology happens to be phylogenetically constrained - which  
> is rather complicated).

Exactly my point. Egg structure is lepidosaurian. Therefore look in that 
direction for answers. 

My best to you, always,

> Cheers,
> --Mike
> Michael Habib, M.S.
> PhD. Candidate
> Center for Functional Anatomy and Evolution
> Johns Hopkins School of Medicine
> 1830 E. Monument Street
> Baltimore, MD 21205
> (443) 280-0181
> habib@jhmi.edu

David Peters