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Re: Steadman's review of Mesozoic Birds
From: "Tim Williams" <firstname.lastname@example.org>
Subject: Re: Steadman's review of Mesozoic Birds
Date: Fri, 30 Jan 2004 12:38:57 -0600
David Marjanovic wrote:
> >The debate over whether the magnetite contained
> >in the Martian meteorite is indeed biogenic
> >(and therefore indicative of past or present life on the Red Planet)
"Therefore"? We'd still have to rule out contamination -- colonization of
the meteorite by bacteria while it was lying around on the Antarctic ice.
IMHO that's quite likely what happened.
This is off-topic, so I'll be brief. (Then again, I started it.)
Terrigenic contamination is unlikely, since the crystals are buried in a
carbonaceous matrix that is itself of Martin composition. The debate has
long since shifted to whether the crystals are of abiotic or biogenic
It is the way Feduccia keeps up his
hypothesis. For example, it is plain obvious from all of his writings that
he has no good working knowledge about dinosaurs.
This is painfully true. Some of his statements about dinosaur anatomy or
paleoecology date from the 1960's. Like David, a lot of the assertions
made by Feduccia and Czerkas and Olson make me cringe. Many of the
assertions have been contradicted over and over again, and in a multitude
of papers (many of which have appeared in such obscure journals as Nature
and Science and American Novitates).
Further, there are the internal inconsistences of his 'hypothesis'. For a
long, long time Feduccia was convinced that the osteological similarities
shared by dromaeosaurids and primitive birds were due to convergent
evolution. Then dromaeosaurids turned up with honest-to-God feathers.
Woops. Suddenly Feduccia was sidling up Czerkas' hypothesis:
dromaeosaurids and birds were closely related after all, but neither evolve
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If I understand Feduccia's stance correctly, his actual contention is not
that dromaeosaurs are related to birds but that forms like Microraptor are
related to birds, and not related to dromaeosaurs. It makes little
difference, one supposes, but nonetheless.
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