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Re: Tucson Tales III.



Stan Friesen wrote:

>Actually, the main reason that the cursorial theory was even
>considered is that Archeopteryx appeared to be a terrestrial
>runner, not a tree dweller.

You're being very kind to the "cladist" camp. To whom did Archie
appear to be a terrestrial runner and not a tree-dweller?
The ornithologists such as Martin and Feduccia have long maintained 
that Archie exhibited arboreal characters(not the least of which is 
flight feathers).  They refused to ignore the arboreal evidence in 
spite of the widespread acceptance of the therapod-bird hypothesis.
---
Stan Friesen wrote:

>A recent analysis of the foot structure of A. has cast doubt on this
>interpretation, sugggesting that A. was a percher - an arboreal
>biped.  This changes the balance, and suggests that the arboreal
>model is pefectly consistant with A. as an early bird, *and* with
>the dinosaurian origin of birds.

Everything you say here is consistent with Feduccia's study except 
the part about changing the balance and the part about the dinosaurian 
origin of birds. Feduccia never thought any balance needed changing,
he recognized the arboreal characters of Archie all along. This study
just adds one more arboreal character to an already extant list that
Feduccia and Martin have been expounding for years. Maybe it changed 
the balance for you and others, but to be fair, no balance needed
changing for the ornithologists. I wouldn't be surprised if the wild
cursorial theories that were becoming widely accepted actually prompted
Feduccia to pursue this line of research, all the time knowing in his
own mind that the evidence points to an arboreal Archie.

With respect to the dinosaurian origin of birds, Feduccia says:

"If Archaeopteryx lived in trees, it means that it evolved not from
dinosaurs as most paleontologists currently believe, but from some
tree-dwelling reptile, since dinosaurs lived on land and not in trees".
---
Stan Friesen wrote:
>
>I don't know, since those results you mentioned are all very recent
>are you sure the non-arobreal theory still has many adherents?

They haven't thrown in the towel yet, although Ostrom is softening
up a bit. He says "I think Alan has put together a very solidly based
study. I'm not set in concrete." (from Science News, Feb 6, 1993)
I can't find a reference at the moment but I recall either Padian or 
Gauthier coming out swinging against Feduccia's paper last year.
---
Stan Friesen wrote:
>
>Or perhaps he is so commited to his personal theory that he
>cannot see the contrary evidence?  Given Feduccia's evidence
>proper application of the cladistic method no longer necessarily
>implies a non-arboreal origin.  To claim that Padian's position
>is due to cladism is probably inaccurate.

I totally agree with this. The main point I've been driving at with
this whole thread is that you can't ignore evidence because it conflicts
with your preconceived ideas. I didn't mean to suggest that cladism
is to blame, actually I think cladistic studies are useful. It's what
you do with the information that counts. The "cladists" in this example
thought they could use their model to infer something beyond it's
scope. They ended up endorsing a cursorial origin of flight, something
that required that they ignore hoatzin-like wingclaws, upright posture,
flight feathers, and now perching-type footclaws in Archie. They also 
concocted some _very_ implausible scenarios for getting a running animal 
to evolve flight feathers. Padian's position is not due to cladism, but
rather the over-reaching conclusions he draws from his cladistic model 
and his disregard for contradictory evidence.
---