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Re: Belly Ribs



Daniel Bensen wrote-

> My question is this: How wide-spread are belly ribs?  Modern birds don't
> have them---when did they go away?  Do crocodiles have them?  What
> groups of dinosaurs have them?

Gastralia were lost in the (Jibeinia + Ornithothoracines) clade.  Both
confuciusornithids and Longipteryx have gastralia, as do more basal
theropods, herrerasaurids and Eoraptor.  Basal sauropodomorphs and
Gongxianosaurus have gastralia, but later sauropods (at least all
eusauropods) lost them.  I'm fairly certain all ornithischians lack
gastralia.

Steve Brusatte wrote-

>Are gastralia known from the feathered dinosaurs?  I really don't know, and
their presence >or absence may say something about the respiratory system of
theropods and perhaps >early birds.

Yes.  Sinosauropteryx, Caudipteryx, Microraptor and probably cf.
Sinornithosaurus have them.

David Marjanovic wrote-

>*Confuciusornis*? That's news to me. Did it really have gastralia?

Yes, both Confuciusornis and Changchengornis have gastralia.  Confuciusornis
has eight rows, described in details by Chiappe et al. (1999).  Some
specimens lack them though.

Mickey Mortimer