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Re: pterosaur debate



DPterosaur@aol.com
<<1.  Are pterosaurs dinosaurs, ornithodires or derived eosuchians close to
protorosaurs?>>

Pterosaurs are definately Ornithodires.  They have in my opinion a 
place pretty darn close to the "accepted" definition of dinosaur (the 
most recent common ancester of the Saurischia and Ornithischia).  
Also, in my opinion, the definition of Dinosaur should be redefined to 
Bakker's.  I think that the "accepted" should be relabelled 
Eudinosauria.

<<2.  Were pterosaurs bipedal or quadrupedal or both?>>

Ooh.  I really have no idea.  I think that they probably stood around 
on two legs, and could sort of waddle walk.  If they needed to go 
faster on the ground, they could use their hands.  I am not sure why 
some such as Padian, claim that Pterosaurs were capable of running 
bipedally on the ground; hey, why run away when you can fly away?

<<3.  Were pterosaurs plantigrade or digitigrade?>>

Digitigrade.

<<5.  How was the pterosaur femur held, parasagittally and nearly 
horizontally, parasagittally and ventrally, or chiefly laterally?>>

In the earliest Pterosaurs, the femur was directed more downwardly 
(almost as much as in a dinosaur's), then reverted to a more 
sprawled stance due to arboral quadrupedalism.

<<6.  What was the function of the 5th toe of rhamphorhynchoids?>>

It held an "airbrake" sort of membrane that aided in landing; i.e. larger 
webbing area imbetween the toes.

<<7.  Did rhamphorhynchoids have a uropatagium between the hind 
legs?>>

Where between the legs?  Probably between the knees and the stomach and
between the ankles and the tail base.

<<8.  What was the exact shape of the pterosaur wing membrane 
and how was it tensioned?>>

The wing membrane extended to the hip, not at all in any way shape 
or form was it attatched to the legs; at all.  The Vienna specimen of 
Pterodactylus who's prepariters claim prove that the brachiopatagium 
reached to the knees does not prove a thing.  On the left, the wing 
finger is crossed over the leg so no detail can be seen.  On the right 
side, the knee is pointed straight into the leg, so of course it looks 
like it attatches there.  The Sordes specimens prove nothing either.  
If we are to believe it wholeheartedly, it shows that the wings 
extended way out in front of the hand, past the toes, and half way 
down the tail.  In Ranger Rick's Dinosaur Book (yes, it is a technical 
reference : ) there is a picture of Rhamphorhynchus on page 48 that 
shows the femur completely free of the wing membrane.  Since all 
Pterosaurs are skeletally almost identical (Ya, I know they're not 
exactly), it is logical to assume that all pterosaurs had similar wing 
membranes.  Also, in an upstroke, either the leg stays where it is in 
the wing and destroys the airfoil, or it gets dislocated.  They were 
stressed with what are called aktinofibrils.  They are little ridges on 
the underside of the wing that ran sort-of parallel to the body.

<<9. Why did the 5th toe and tail become reduced in 
pterodactyloids?>>

I think the tail got reduced because the head got big and they started 
to stear from the front, not the tail; therefore reducing the need for it.  
Since they steared from the front, they probably needed smaller 
airbrakes, so therefore, the toe got reduced.

<<10.  Are there any flightless pterosaurs?>>

Not that I know of.

<<* Explain the persistence of sharp and large foreclaws.>>

I don't know?  Maybe helped in dispatching prey, manipulating eggs 
and or chicks, mating aids.  Who knows?

Kevin Padian is a lurker on this list (I think).  If you get him pretty 
darn exited (say.. claiming that Pterosaurs couldn't flap), he might 
respond : ).

Peter "Hoping that Kevin Padian will join the discussion" Buchholz
Stang1996@aol.com