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Re: Thou Shalt Not Climb!



--- mariusromanus@aol.com wrote:

> It still looks as if we are using the derived state
> as evidence... very 
> akin to saying, "Whales never used their back legs
> in aqueous 
> locomotion, since as we all know, whales today use
> flukes."
> 
> So, what I'm wondering, is how did selection take
> place for 
> pre-perching birds that were landing in trees with
> zero adaptations for 
> such?

+++++++++++++++++++++++++++++++

How about those long, counterbalancing tails in
Archaeopterygiformes? Having that counterweight might
have allowed for grasping toes to be more than enough
to allow them to stay on a branch without the need for
opposability.

The opposable hallux might have evolved in tandem with
the shrinking tail. Offhand I don't think that's what
the evidence shows. Regardless, this part would be
easy  enough to test. Admittedly it would be nice if
we had a better record of tail loss in birds.
Currently, things seem rather polar. We have long
tailed _Archaeopteryx_ and _Rahonavis_ on one end, and
the tail-less rest of Aves on the other.

Anyway, there's one thought.

Jason

"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." - Alfred S. Romer


      
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