origins of flight

[brushes2@juno.com]

Donolisters,

I?m not sure that this has not been previously discussed on this list,
but it is important. Ken Dial (University of Montana) had extended his
work on flight to look at locomotor behavior in newly hatched birds.  His
work is based on studies of 3 species of post-hatchling precocial
Gallinaceous birds (Chuckar Partridge, Japanese Quail, Ring-neck
Pheasant).

The model combines high-speed video and Doppler radar to study the daily
progress of vertical and horizontal accelerations of flight and
terrestrial locomotion and morphometrics of wing development. (wing
loading, feather growth).

Even 1 day old chicks jump vertically, vigorously beat their featherless
forelimbs, and swing their hind limbs through an arc similar to that used
during over-ground running when trying to escape being handled.
Throughout development the forelimbs produce significant aerodynamic
forces that assist the legs. These activities enable birds to ?run
vertically? and achieve substantial heights against such rough surfaces
such as rocks, cliffs, and tree trunks.

Dial labels this the ?Assisted Vertical Running Hypothesis? and considers
it an alternative to either the Arboreal (tree-down) or Cursorial
(ground-up) hypotheses. He points out that both these hypotheses are
dominated by paleontological evidence which fails to adequately address
the incremental adaptive stages necessary to achieve fully developed
flight mechanics. The maneuvers in ?Assisted Vertical Running? are both
consistent with fossil data and provides incremental adaptive plateaus
along the ontogenetic projection that leads to fully developed avian
flight mechanics. It is interesting to note that from the very beginning
the 2 locomotor modules produce different patters fore and aft but are
coordinated by the nervous system. The forelimb uses the musculo-skeletal
pattern of flight even before the flight feathers appear.

I?m not sure that this has been formally published. My information is
based on an abstract presented at the SICB meeting. The work is unique in
that it includes some of the first actual measurements on the acquisition
of the locomotor capabilities that lead to flight. 

Cheers,

Alan


brushes2@juno.com