From: Betty Cunningham <bettyc@flyinggoat.com>
Reply-To: bettyc@flyinggoat.com
To: dinosaur@usc.edu
Subject: Re: bauplan convergence
Date: Fri, 16 Jun 2000 19:53:24 -0700
#4 -parachuting just doesn't mesh for me as a reason for developing
proto-flapping.
Consider this; a glider wouldn't want to flap as it throws off stability
and control of a glide. I picture the early aviators pumping away like
mad on their flapping machines as they leap off of cliffs and just
basically plummeting a lot (sure, weight was a major factor then, but
the flapping just didn't aid the plummett one dang bit).
A gliding animal wants fairly immobile wing positions to parachute
with. A flying animal needs to flap and parachutes both.
An animal that is already flapping to attract females or to scare away
intruders is a prime candidate to have leaping out of trees or leaping
up in the air WHILE FLAPPING and thus accidentally discovering flight,
than a creature that simply leaps out of a tree with the intention of
getting to the ground.
Gravity can get ANYBODY to the ground that leaps out of a tree.
Gravity, air, and a little extra skin on the arms gets you parachuting.
But parachuting doesn't require that you flap.
-Betty Cunningham
Stanley Friesen wrote:
> I didn't say I thought it was viable - it just came closer than most
other
> alternatives.
>
> My own preferred *hypothetical* sequence is something like:
> 1. Development of protofeathers for a combination of insulations and
> display. (essentially, self-reinforcing feedback), leading to:
> 2. Enlarged display/brooding feathers on the arms.
> 3. Development of a scansorial/arboreal lifestyle in a small form,
allowing:
> 4. Co-option of display feathers as a parachute/proto-wing.
> 5. Elaboration of new function by natural selection for improved aerial
> safety/agility.
--
Flying Goat Graphics
http://www.flyinggoat.com
(Society of Vertebrate Paleontology member)
-------------------------------------------<,D,><