RE: First dinosaur eggs found ready to lay in mothher

[Tim Williams <twilliams_alpha@hotmail.com>]

Jeff Hecht wrote:

> The pelvis of an oviraptor includes two eggs with shells in place, almost 
> ready to lay, showing that theropods had two working oviducts, in contrast 
> to the one of birds. It also shows that dinosaurs laid pairs of eggs in a 
> series of sittings to make a whole clutch, not a whole batch at once. The 
> paper is in the just-out Science; the story with photos is at
> http://www.newscientist.com/article.ns?id=dn7267

> From the article:

The fossil "is absolutely stunning", says Ken Carpenter of the Denver Museum 
of Nature and Science in the US. Capturing a moment so close to when a 
female dinosaur was to lay her eggs makes it "one of the most remarkable 
discoveries yet".

I couldn't agree more.

AFAIK, the condition in the vast majority of Mesozoic birds is unknown.  
Thus, one or more of the avialan clades (_Archaeopteryx_, enantiornithines, 
hesperornithiforms, etc) may have retained the twin-oviduct condition seen 
in oviraptorosaurs.  When did the single-oviduct condition first arose in 
Avialae?  Phylogenetic bracketing tells us the first neornithines had it - 
but we can't push the bracket down the tree any further (or can we?).

Cheers

Tim