Re: Good mother dinos

[rowe@lepomis.psych.upenn.edu (Mickey Rowe)]

Martin asks (for someone else):

>> 1) How can you tell from fossilized bones whether any particular
>> species of dinosaur was a "good mother" or cared for its young?

For a more complete layman's discussion, see Jack Horner and James
Gorman's book _Digging Dinosaurs_.  In brief, you can infer from the
bones of juveniles whether or not they were capable of walking right
after they hatched, and you can look for complete eggs vs. fragments.

In the case of Maiasaura, there is evidence that when the young
hatched, their long bones weren't fully ossified, so the animals
couldn't support their own weight.  The obvious inference is that food
had to be brought to them until they outgrew that condition.
Secondly, Maiasaura nests almost never contain large pieces of
eggshells.  That's not the case in the hypsilophodont nests Horner has
excavated.  The inference here is that after the young hatched, they
hung out in the nest, and broke up the egg shells as they moved
around.  The hypsilophodonts apparently had fully ossified bones upon
hatching, so they clambered out of their shells and scooted right
away, leaving large egg fragments untrampled.

I'm sure I've forgotten other evidence, and possibly mangled the
above, but I think that's a fair start.

-- 
Mickey Rowe     (rowe@lepomis.psych.upenn.edu)