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Re: Daddy day-care: dinosaur fathers guarded the eggs

--- On Thu, 12/18/08, Janet m vandenburgh <van02@cox.net> wrote:

> From: Janet m vandenburgh <van02@cox.net>
> Subject: Daddy day-care: dinosaur fathers guarded the eggs
> To: "Dinosaur@usc.edu" <dinosaur@usc.edu>
> Date: Thursday, December 18, 2008, 7:38 PM
> http://www.msnbc.msn.com/id/28302741/
> updated 59 minutes ago
> WASHINGTON - By Will Dunham
> You can call it dino daddy day-care.
> Scientists who examined the fossilized remains of three
> types of
> medium-sized dinosaurs found with large clutches of eggs
> have concluded that
> the males rather than the females seem to have guarded the
> nests and brooded
> the eggs.
> Writing on Thursday in the journal Science, they said this
> behavior is seen
> in certain existing species of birds. Scientists believe
> birds evolved from
> small, feathered predatory dinosaurs more than 150 million
> years ago.
> The three types of dinosaurs, Troodon, Oviraptor and
> Citipati, lived roughly
> 75 million years ago and were theropods -- the primarily
> meat-eating group
> that also includes monstrous beasts like Tyrannosaurus rex
> and
> Giganotosaurus.
> "There are a lot of characteristics that we once
> thought were unique to
> birds that are turning out not to be -- that they first
> arose in their
> theropod ancestors," Montana State University
> paleontologist Frankie
> Jackson, one of the researchers, said in a telephone
> interview.


>From the article:


"Florida State University paleobiologist Greg Erickson said there was no 
evidence of medullary bone -- the extra bone that breeding female birds and 
dinosaurs use to make eggs -- or evidence of another process by which female 
reptiles such as crocodiles acquire mineral salts to make eggs."


I don't buy it. 

Why would one expect to see either of these processes in an animal that was 
found watching eggs that were already laid? Medullary bone and the other 
(unfortunately unnamed) process occur in gravid animals, not ones that have 
already laid their eggs.