Re: Origin of feathers

["Norton, Patrick" <Patrick.Norton@state.me.us>]

Two snippets from Matt Troutman's 4/19 post (and using up my 3 for the   
day!):

>There also is the problem about how it will develop the proper flight   
musclature ; ..most bipedal animals that move quickly ( macropodids )   
have their forelimbs tuck in so drag is not produced. Since, to be able   
to achieve maximum running potential you have to keep the forelimbs   
tucked in, there is no way that the animal could have achieved high   
speeds or develop strong musclature.<

I lived in the Sonoran desert of Arizona for a few years. One day I was   
lucky enough to observe a roadrunner stalk, fight and kill a rattlesnake.   
 Roadrunners (_Geococcyx californianus_) aren't well adapted for flight,   
but the way they use their tail and wings during hunting is remarkable.   
In the attack I witnessed, the roadrunner used its foot-long tail as a   
combination rudder and flap, swiveling it in order to change course, or   
raising it upright to use as a brake. The wings were outstreched during   
the attack, beating to fluster the snake and often to thrust the bird   
upwards or sideways a few feet out of striking range.

>Tennekes in '96 showed that it requires 4 times as much power for birds
to take off from the ground. This is another problem for the cursorial
origin of flight ; it requires animals to assume their maximum muscle
usage for primitve take-off. Even when the animal runs to get enough
speed to take off when it jumps it would stall too much for take-off!!!<

I think the assumption in most energetics studies that protobirds ran   
around trying to chase insects into the air is all wrong. A small   
cursorial archosaur with undifferentiated feathers occupying a niche   
similar to today's roadrunner would be a prime candidate for rapid   
modification of wing and tail feathers---not for flight--but to obtain   
aerodynamic advantages over prey during combat.  The hopping, bobbing,   
weaving, jabbing strategy of the roadrunner requires all the architecture   
of flight; yet they rarely fly. But the advantages those adaptations   
provide in a predator/prey confrontation are enormous. If  you're trying   
to get protobirds off the ground, don't think speed; think agility.