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Re: Hone and Benton 2007 (their second paper)
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Sent: Monday, June 04, 2007 9:04 AM
Subject: Re: Hone and Benton 2007 (their second paper)
Fair enough! Actually, the idea that Archaeopteryx didn't go up trees
terribly frequently, except to gain altitude for a launch does not bother
me at all. I was merely challenging the uncritical acceptance that
Archaeopteryx could fly...and will continue until someone bothers to test
John Ostrom asked me to do just that shortly before the Ostrom symposium
several years ago. If I remember correctly, some quickly done flapping
calculations indicated that it sould be capable of decent flapping flight
performance given a pectoral mass fraction of roughly about 7% (about half
that of a typical modern bird). It didn't glide too well -- about 2/3 the
gliding performance of a pigeon unless the tail was cascadable, in which
case performance would have been substantially improved. I have no idea
whether the tail was cascadable though. I also did some rather elementary
launch calculations that convinced me that it would be able to launch from
the ground without significant difficulty (though I didn't buy into the
Burger [sp??] ground effect vs. speed hypothesis). That said, I don't doubt
that Archie could get into a tree if he wanted to and don't doubt that he
could launch from there -- just don't see the need for it.
In point of fact Archaeopteryx almost certainly could go up some types of
trees. My problem is that there is little or no phylogenetic evidence
that supports this; that is, Archaeopteryx does not exhibit any
evolutionary specializations for arboreality relative to its ancestors.
Arguing that abroreal behavior "still may have happened" is all too often
a non-testable response to avoid looking at other hypotheses. Of course
it may have been true, but considering how many adapations later avians
show for living in trees, it sort of feels like special pleading to argue
that Archaeopteryx "could have" despite the lack of positive evidence.
Scott, I wholeheartedly agree with you about that.