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Re: The ground-nowhere hypothesis on the origin of bird flight



I suspect feathers played a number of roles in theropod/bird evolution. One 
sign of that is the diversity of feathers in non-avian theropods. 

One specific hypothesis I have been wondering about is the possibility that 
feathers may have served as a predator-deterrent or -discourager. An extreme 
possibility would be a dino/bird counterpart of a porcupine, but a more 
realistic one is that feathers simply get in the way of predators. I once 
watched a hawk eat a sparrow it had snatched from the neighbors' hedge, and saw 
that it took a long time to get rid of the feathers before devouring the 
remains. Giving a predator a mouthful of feathers rather than a mouthful of 
flesh could be an evolutionary advantage. Even if the prey didn't survive, the 
predator might be less interested in prey that took a long time to eat. 

I'm sure that wouldn't be the only reason to evolve large feathers, but it 
might have contributed to the growth of larger feathers that eventually were 
adapted for flight. And maybe somewhere in China there are fossils of 
prickly-feathered dino-birds. :-) 

At 11:04 PM -0300 10/8/09, Augusto Haro wrote:
>A little speculation about the elongation of the forelimbs in
>paravians and the development of remiges:
>
>If relatively small hyperextended claws are primitive for paravians,
>they may suggest some seriema-like predation in early paravians, which
>use this claw to hit small prey. In snake-killing birds, extending
>long feathered wings permit to fool venomous snakes by getting them
>trying to bite feathers. Feathers on the hind legs will have also
>added to the posibility the snake does not aim to the non-feathery
>part of the limb. Perhaps feathered extremities like those may imply
>an advantage against venomous prey in animals which could not perform
>flapping flight (if they really performed it). Of course, for this to
>represent a selective advantage, we should hypothesize the venomous
>stuff was some common food source.
>
>It only rests to know how many snakes, or some other venomous small
>vertebrate prey (mammals with venomous spikes on ankles? varanoids?),
>were there in the Late Jurassic/Early Cretaceous.
>
>Don't get angry... :-)

-- 
Jeff Hecht, science & technology writer
jeff@jeffhecht.com or jhecht@nasw.org
Boston Correspondent: New Scientist magazine
525 Auburn St., Auburndale, MA 02466 USA
tel. 617-965-3834  http://www.jeffhecht.com