Re: Hone and Benton 2007 (their second paper)

[jrc <jrccea@bellsouth.net>]

----- 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