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Re: pterosaur launching tactics
Without the images being available to me, I can't comment on specifics. I
do note in passing that either type Quetz would not have the power to launch
bipedally without special, transient conditions in the atmosphere (severe
wind gust, etc.). Quadrupedal launch does not require special condtions.
----- Original Message -----
From: "David Peters" <firstname.lastname@example.org>
To: "Dinosaur Mailing List" <email@example.com>
Sent: Monday, June 09, 2008 10:59 PM
Subject: 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. and A.