altricial nestling bone fossilization

[david peters <davidrpeters@earthlink.net>]

To my question, I recently received the following answer from a noted bird 
expert at a major metropolitan museum (name withheld 'cause why should I drag 
him/her into this?). 

Q: Are altricial nestling bird bones sufficiently ossified to fossilize?

A: At later stages they might be under favorable conditions.

Still waiting for an answer from my bat expert. Not sure what the situation 
would be with dependent marsupial young. Any thoughts, references or discussion 
along these lines would be appreciated.

David Peters
St. Louis