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Re: Jeholornis - long-tailed bird in today's Nature



  Well, not seen the paper, but i will be up to the advocate Tim has
offered and suggest this disclaimer, to advocate ajn alternate hypothesis
to a dino-bird link. The animal is a theropod dinosaur, small that evolved
several convergent features in common with birds, but it is clearly not a
bird as it lacks feathers. Note that in the Yixian, all birds have
feathers or are clearly modified in way only associated with feathers or
flight, such as a long pygostyle, large sternae, etc. Quite obviously,
this animal evolved convergent arm structure with birds, not because of
flight, but because the animal had a need to exapt its limbs for grabbing
things, á la Ostrom's series, or for arboreal scampering, which is seen in
many primates that similarly evolve very long arms with needs for
opposability in the foot and a balancing tail. It does not in the least
advocate an origin for birds from theropods.

  Now, having said this, note that I am not an advocate for the
non-dinosaurian origin of birds, but I do like thinking on the other side
of the coin.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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