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RE: 3 x Re: flight stroke (pretty short)



Graydon wrote:

> Which suggests to me that all the gliding models we've got to observer
> are wrong, and that things like the assisted vertical running hypothesis
> are on the correct track.


Most gliding-->flight models (those usually termed "trees-down") propose
that pro-avians had a lifestyle similar to modern gliding mammals (e.g.
"flying" squirrels, "flying" possums), and that gliding was used by
pro-avians to commute between trees.  Gliding is an extremely efficient form
of travel, and allows an arboreal mammal to get from one tree to the next by
bypassing the ground.  

However... gliding models in which the pro-avian leaps from the trees to the
*ground* are a totally different matter.  For one thing, they avoid the
assumption that gliding is simply a better way to commute between trees, and
therefore require that the ancestors of birds were obligately arboreal
(which they obviously were not, contra Feduccia).  

Among modern vertebrates, "flying" frogs (_Rhacophorus_) use gliding to get
from trees to the ground - and with their 'gliding' membranes located at the
*end* of their limbs, the emphasis is on maneuverability rather than
lengthening the flight path.  



Tim