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Re: Scansoriality in Scansoriopteryx?



Michael Lovejoy (michael@palaeoproductions.fsnet.co.uk) wrote:

<Just a quick question to anyone who has an opinion: Why is
Scansoriopteryx thought of as arboreal? What evidence is there?  (HP
Jaime's post just confused me even more: arboreal feet and terrestrial
hands? Sounds more like a percher than a climber.)>

  The main reasons I have been given were that the arm was really long
with a physical adaptation seen in some primates or in birds, indicating
it was arboreal. I do not buy their reasons.

<PS Does this animal (or Epidendrosaurus) have an SLC? (or any other
evidence of arm-folding ability)>

  Here's the thing, there's a small carpal in the wrist of Czerkas'
specimen; it is semicurcula in form, and there's what appears to be a
trochlear groove, but it's not on the curved side but on the flat side. I
have restored this as a semilunate carpal, however, just to be safe. The
distal ends of the radius and ulna appear to be crushed, they are broadly
flattened with fracturing on the surface, and I do not trust their shape
more than I could throw the thing. If there was an arm folding ability, it
was minimal, and the glenoid faced ventrally, not laterally, and certainly
would not have permitted over-shoulder rotation of the arm as was
hypothesized by Zhang et alii for *Epidendrosaurus*. You would think with
a hand like that it would have folded better, but this may be due to its
possibly "non-adult" nature.

  My opinion...

  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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