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BCF ET CETERA
Recently, Jon Wagner and John Jackson have engaged in another discussion of
BCF versus ground up hypothesis. I posted a message to the list over a year
ago, detailing what problems I have with the BCF theory as detailed by George
Olshevsky in Omni four or five years ago.
I believe it was titled something like "A whole lot of trouble" or soemthing
similar (I'm sorry I can't be more specific with the title or URL, but browser
is totally broken and freezes my computer and I haven't been able to get that
dealt with yet) in October 1996.
In summery, I stated that I thought that the basic idea that tree dwelling
dinosaurs were the immediate precursors to birds and many of the flight
addaptations like the retroverted pubis, sternum, etc were due to the fact
that these animals were living in trees and jumping around using the feathers
that they already had (for insulation and display) to slow their falls and
direct their movement.
Now again, I state I agree the evidence for tree dwelling dinosaurs jives with
the anatomy of the dinosaurs more than strictly terrestrial dinosaurs do.
Even Padian and Gauthier's famous "maniraptorial power stroke" or whetever
they call it can be explained better in the context of living in trees.
John Jackson was right in questioning the usefulness of the power-clap in prey
grabbing. The anatomy just doesn't jive with it - the head is in the way, the
prey animal would have to be directly in front of it, and the arms aren't long
enough to grab anything but the distal tail of said prey animal. I don't have
refs or measurements on this, but I could easily draw a picture and scan it to
Now, instead of grabbing a prey animal, suppose that instead, it was grabbing
onto a tree trunk? Remember that in the mid-Jurassic when the power clap
first evolved, most of the trees had really really long trunks (conifers,
palms, cycads etc) with a general lack of large undergrowth branches, so the
main way to get up the tree is to climb up the trunk, rather than hang on
Imagine say a small Ornitholestes or Compsognathus looking animal stradling a
tree trunk, pulling up with its arms using the power-clap to keep it's hand
level, while flexing its arms and pulling its body up. I can draw pics of
that too and scan them if anyone wishes as well...
In any case, if any of you thought that I'm completely bananas for not talking
about Ornithopods, you're wrong. Does anyone out there have Galton's 1997
paper on Thescelosaurus pub'd in the Swiss Journal 'Revue Paleobiologie'?
This journal isn't even in georef and I would be eternally greatful to anyone
who could perhaps send it my way. I've got lots of stuff that I could send in
Like to a babe in his mother's robe,
Thou art enshrouded in my love.