[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
re: pterosaur launching tactics
Mike and John [see addendum at the bottom of this letter],
and a copy [without images] to the dinosaur list:
I've attached lateral view images of four pterosaurs, each with its
own proportional configuration problems/solutions in getting around
MPUM 6009, as you can see, retains the long legs of its ancestors,
something all other pterosaurs lack. A pterosaur with such
proportions would have about as much luck with a quadrupedal launch
as a lemur.
Nyctosaurus and Arthurdactylus have such long wings proximal to the
fingers that it's hard to see how they could _not_ move about
quadrupedally. They look burdened by their wings. Any sort of launch
would appear awkward and perhaps, goony.
On the other hand, Quetzalcoatlus, IMHO, seems well equipped for
terrestrial locomotion, able to move about quadrupedally and to lift
its wings readily. It also seems to have the best proportions in the
hind limb and pelvis of the latter three to launch bipedally. In any
case, among the pterodacs, the ability to extend the wings laterally
while bipedal might have been sufficient to enable that first flap to
get airborne (without hind limb assist), and thus they may have been,
in a strict sense, launched by their forelimbs.
I might suggest that the relative brevity of the humerus in Q.
provides less leverage for forelimb launch, but perhaps you guys
don't rely strictly on this lever for your launch. Still, while I
don't discount it, I'd like to see your version before guessing wrongly.
Anyway, this is the database from which I'm working. Interesting
creatures. Answers don't come easy. All of us should work together to
With regard to the vampire bat, Desmodus, despite its remarkable
secondary abilities, phylogenetically, the muscularity and
configuration of the hind limbs is so out of touch with any sort of
standard tetrapod upright locomotion that there really is no hope for
the hind limbs to assist in takeoff. In this case, they act more like
the tail wheel of an airplane, keeping the butt off the ground. More
importantly, please note that the fingers of Desmodus are beneath the
humeral glenoid, the bat's center of gravity. The hindlimbs and its
toes are far from it, which is not the case in pterosaurs, as you can
see by the drawings. That's why in Desmodus the launch has to
originate with the forelimbs.
Addendum: I do note that in Q., like Pterodactylus, in the bipedal/
quadrupedal configuration, the fingers are also below the center of
gravity, the humeral glenoid. That is not the case with Nyctosaurus
and Arthurdactylus. So what works for Q. and P. may not work for N.