Re: Wedel's paper

[HPB1956@aol.com]

Katarina Katarinaki wrote:

> I believe that this suggests that the airsacs did
> emerge very early in archosaurian evolution and was
> perhaps lost secondarily in some taxa. This may also
> give us the physiological basis for why dinosaurs were
> able scale up so well in comparison to mammals or
> modern reptiles. Has anyone produced revised mass
> estimates based taking the airsacs into account?

Gregory Paul answered this question for sauropods earlier on this list. 
I think his remarks cover also early archosaurs which may have been
less pneumatic than early sauropods.

> Someone brought up the issue of seriously overestimating mass of sauropods by 
> failing to account for high sacs. Nein, nein, nein. Even in super pneumatic 
> birds air-sacs drive specific gravity down to 70-75%, and no sauropod was 
> anywhere near as filled with air spaces (long bones solid, sacs probably did 
> not line the sides of the belly as in flying birds). Air sacs probably 
> decreased sauropod density only 5-10% (this varied between species since 
> primitive ones were less pneumatic than latter). Since an individual animal 
> can normally vary in mass by 30% in a given year the air space issue is 
> actually rather trivial.

> G Paul

Cheers


Heinz Peter Bredow