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Re: Terrestriality is a bias



In a message dated 6/11/00 3:38:04 PM EST, dannj@alphalink.com.au writes:

<< It seems that birds are unique amongst actively flying vertebrates in
 that the hind legs have been kept quite separate from the flight
 surfaces. I suspect this is no accident. I think that early flying birds
 were decended from creatures that spent as much time on the ground as in
 the air, to the point that their hind legs remained important
 structures. Hence, bird flight could have developed from both the ground
 up AND trees down at the same time, which would explain why neither
 theory has gained strongly against the other. >>

A good set of hind limbs can help an arboreal animal if it is ever grounded, 
of course, and good running ability would be very useful in ground-level 
takeoffs once the forelimbs have evolved into wings. I have no problem with 
this kind of "ground up" scenario; I do have problems with "ground up" 
scenarios that do not admit to a substantial arboreal (or scansorial, if you 
like) history for bird ancestors.