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Re: Comparing T-rex to pterosaurs was (Re: pterosaur tracks from SVP)



Betty Cunningham wrote:
> Are you forgetting the rather stiff wings sticking to the rear of the
> pterosaurs?  These would not have been neatly folded into thirds and
> tucked into the body as birds do.  They'd stick out (to the rear) from
> the wrist at nearly a full extension length on each side.  The
> wingfinger struts probably acted as much as a counter balance to this
> animal's front end as the tail of T rex did to it's front end -bipedally
> or quadrepedally.
Looks to me like you still have the same excessively forward-pitching
problem, only now you mention that there's another factor involved:  I can
conceivably see how there might be as much bone compacted within the space
of the skull as there is spread across the  length of the two wing fingers
and a comparable amount of soft tissue adorning both at either end (I have
no data on this so I don't know, but personally including soft tissue I
think it's unlikely).  Anyhow, assuming one cancels the other out, you still
have a lifting area created by the skin wing membrane - one primarily aft of
the centre of gravity.  ANY gust of wind ahead of, behind or to the side of
this animal (as Dan touched upon) is liable to incline it's rear into the
air and it's nose toward the floor.  And woe betide it should try moving at
any speed like this - wing in ground effect would have a field day!  Okay so
this is an exxagerated scenario as I'm sure pterosaurs had more than enough
shoulder muscle control to balance this upward force on their wing tips, but
to what effect?  It's certainly not the most energy efficient state of
being.
She then said:
> Your comment about animals with reduced tails may be more reason to
> beleive these animals were quadrepedal. (and the quadrepedal tracks, of
> course.)
I'd say so, yes - it seems to me that to be a biped with limited neck
manouvrability, you HAVE to have a tail or bring your chest cavity directly
above your legs (for an example of this, look down)
> One note of interest from the talk -they couldn't get a rhemphoryncinoid
> of any type to walk succesfully in ANY of the 3 postures, only
> pterosaurs.
> The long tail was a problem in ALL postures they've tried.
Amazing!  Could this be the third wonder of the palaeophysician world?

Samuel Barnett