Patagium attachment Was: Re: Pterosaur.net

[mhanson54@comcast.net]

Lately I'm seeing claims made like this, and this quotation from the 
Pterosaur.net site has piqued my interest:

"The more basal, paraphyletic “ramphorhynchoids” had a broad uropatagium 
that linked across the two hind limbs. By contrast, the pterodactyloids 
had a uropatagium that was split, such that a roughly triangular 
membrane ran along each hind limb [figure 3a]. The uropatagium would 
have had several uses during flight."

This seems to imply that the uropatagium did not attach to the tail. I 
am wondering where the evidence for this comes from. It seems that the 
only specimen that could potentially be interpreted as having a free 
tail is the Sordes pilosus holotype, however, there is a peculiar fold 
down the centre of the patagium that could be interpreted as the region 
on which the tail originally attached, and due to decay it fell off. 
Also, I am interested in how the long bony struts in the final caudal 
vertebra of Pteranodon is interpreted if the tail is unattached. 
Additionally, what would be the aërodynamic implications of a free tail?