RE: paleonet Origin of birds

["Jack" <jpenkethman@xxxxxxxxxxx>]

If anyone has time for this: How can you tell whether it was the ancestor of
the flightless bird that could fly, or it will be the descendants that would
become capable of flight. In other words, how can you tell the direction of
evolution from a fossil?

Jack

P.S. The discussion here on the origin of birds answers a creationist
criticism that birds should have evolved, if they evolved at all, from
ornithicia and not from sauriscia as claimed. But enough of that!


-----Original Message-----
From: paleonet-owner@nhm.ac.uk [mailto:paleonet-owner@nhm.ac.uk] On Behalf
Of Dinogeorge@aol.com
Sent: Monday, April 11, 2005 3:02 PM
To: paleonet@nhm.ac.uk
Cc: Dinogeorge@aol.com
Subject: Re: paleonet Origin of birds


In a message dated 4/11/2005 12:48:57 P.M. Pacific Standard Time,  
tdemko@d.umn.edu writes:

>>Dr. Frances James, an ornithologist/ecologist from Florida  State
University, gave a talk here last week where she supposed that the  
Maniraptora, including oviraptors and dromeosaurs, were large 
flightless  birds. It seems that flightlessness has evolved in birds 
numerous times, and  its adaptations completely swamp the characters 
used in typical cladistic  analysis of bird-dinosaur relationships. She 
also was able to point out  several bird-specific (i.e. vestigial flight 
characters) features present in  some maniraptors.

It was almost convincing...I'd like to hear  more!<<
 
Well, I've been pushing this view for some 15 years now. There is indeed  
rampant convergence in dinosaur and theropod lineages as a result of
secondary  
flightlessness, making cladistic analysis very problematic. Think of moas,  
giganornithids, phorusrachids, etc., etc. Forelimb reduction and hindlimb  
enlargement, as adjuncts of secondary flightlessness, occurred repeatedly
in 
Cenozoic birds, why not also in Mesozoic birds?