RE: pneumatization

[Toby White <augwhite@neosoft.com>]

Croc skulls as well.  I have a vague recollection that this goes deeper into 
the archosaurs but I can't track it down.

  --Toby White

On Friday, September 03, 1999 10:35 AM, Dinogeorge@aol.com 
[SMTP:Dinogeorge@aol.com] wrote:
> In a message dated 9/3/99 10:14:43 AM EST, jwillson@harper.cc.il.us writes:
>
> << The only known groups of tetrapods with pneumatization are:
>
>  1) Birds
>  2) Pterosaurs
>  3) Sauropods
>  4) Theropods
>
>  - right?
>
>  No mammals, no non-archosaurian reptiles? >>
>
> You can add small prosauropods to this list. Marsh described Anchisaurus as
> having hollow vertebrae and limb bones. I think Ammosaurus also, if memory
> serves me. I think dinosaurs originated as small animals with some degree of
> skeletal pneumaticization that was subsequently lost in the larger
> prosauropods and ornithischians (a possible apomorphy uniting the two groups)
>
> but developed more extensively in sauropods and theropods independently.