Re: A note on pterosaur nesting behavior

[Mike Habib <habib@jhmi.edu>]

On Jul 24, 2009, at 7:29 AM, David Peters wrote:

> Imagine a bat baby buried.
> The wear and tear on the wing and hind limb membrane as it escapes  
> its burial chamber would be problematic.

I'm not sure that's actually true, and even if it is, it may not be  
applicable to pterosaurs, which seem to have possessed a wing membrane  
with rather different material properties from those of bats.  There  
are living bats that dig and scramble around on the ground, so  
membrane wings are not as much a hazard as it might seem.


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

How so?


> 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?


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

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