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Re: Hone and Benton 2007 (their second paper)

----- Original Message ----- From: <dinoboygraphics@aol.com>
To: <twilliams_alpha@hotmail.com>; <dinosaur@usc.edu>
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 it.

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. JimC