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I was looking at "Diatoms to Dinosaurs" today and the book
confirmed what I started thinking after reading sections of "On Growth
and Form" : That sauropod vertebrae, by virtue of their extensive
excavations, are in effect I-beams. I think it was page 87 and a cross
section of Camarasaurus. Even if the overall mass of the bone was not
reduced, the strength would have been increased. Tubular bones serve the
same purpose, they are in effect circular I-beams.
This isn't of course all the answer, as things like Compsognathus
have hollow bones too and they were not under the pressures to increase
the strength-to-weight ratio that birds were (unless George is right) nor
the pressure to increase this ratio that sauropods would have been. But
it is part of it I'm sure.
It also had a little picture detailing the truly extensive
variety of patagia connecting feet to wings and feet to tail in the
Chiroptera; it does not seem unlikely that pterosaurs could have been
I am still trying to figure out the Chinese longfeather bird. I
had originally thought of the african whidda (widow?) birds which have
very long tails used to attract females. However, they are not that similar.
That bird has barbules all the way down the rachis, and a thin, flexible
rachis, quite unlike the very stiff-looking, mostly bare rachi of the
longfeather bird, and something like four, not two of these feathers. The
resplendant quetzal is much the same. The standard-winged nightjar seems
quite similar but the rachi are very flexible (and they are on the wings).
The longfeather birds, again, had rachi that looked quite stiff and did
not appear to be bending at all, and appeared rather thick as I recall.
Both birds shared this feature so they would both probably have to be males
if it were a sexual feature- not impossible. For all I know it
was just a breeding form of Confuciusornis, I didn't take a good look at
the skull and I saw a restoration of that bird with a similarly short
tail. But if no dimorphism appears, it could concievably be aerodynamic, a
double version of the rhamphorhynch tail. That would be weird. We will
see in a few months I imagine, and I'd tend to go with it as a sexual
feature but I'd be open to the aerodynamic possibility. But would TWO
long horizontal -----------------<<<<<<>
"tails" like this ( they actually were angled apart a bit ) be very good
for maneuvering? I suppose it might work similarly to the forked tail of
the swallow if that's aerodynamic (is that dimorphic?).