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Re: ABSRD BAND on Sinornithosaurus feathers




Thomas,
Since you are interested in what tunes the ABSRD BAND might be singing in response to the Sinornithosaurus paper, here is a posting by a very vocal (but anonymous) member of that group (from sci.bio.paleontology):


"Having read the paper, I would say that the authors have not succeeded in showing that Sinorithosaurus has feathers. Unlike what Jones et al. did with Longisquama feathers, Xu et al. have not shown that Sinornithosaurus' integumentary structures have a hollow core, a calamus, or pulp caps. They have not shown that these structures are follicular in origin. Unlike Caudipteryx, there is also no evidence that Sinornithosaurus has wing feathers. The model of feather development proposed by Prum, and illustrated in fig. 6 of this paper, also makes no adaptive sense. If every stage in the evolution of a morphological structure has to be adaptive, then it is difficult to fathom how a simple hollow cylinder or a pine needle-like branching structure can be functional in an animal.
It is also much easier to evolve the intricate interlocking barbules of avian feathers from a solid sheet (in other words from the type of feathers with solid vanes found in Longisquama) through a process of weight reduction than it is to build the vane up from a clump of loose filaments. Insects, bats and pterosaurs fly with membrane wings, so a solid sheet is the norm for wings; bird wings are also functionally solid sheets. It is therefore foolhardy to fly with wings made from interelocking filaments, not knowing a priori whether the interlocking structures are strong enough or structurally sound enough to serve functionally as wings. To paraphrase Feduccia, such attempts by a theropod to fly may result in a grease spot on the ground. It makes more sense for a volant animal to glide and then fly with solid sheets of feathers and for some descendants of such animals to then experiment with weight reduction methods that would not compromise either the strength or the structural integrity of the wings. Those that succeeded with weight reduction would then be more fit since it will drastically reduce the amount of energy needed to fly.
It is interesting to note that some cladists (in the recent debate in Science; thanks to Rick Toomey for calling attention to that issue) argue that Longisquama does not have feathers despite the fact that such features as hollow core, calamus, pulp caps and follicular origin have been demonstrated by Jones et al. Yet other cladists are willing to believe that Sinornithosaurus has feather homologs despite the fact that none of these features found in both avian and Longisquama feathers has been found in Sinornithosaurus' integumentary structures. It is quite obvious that the cladists are influenced primarily by their cladograms, rather than by the structural similarities between avian feathers and Longisquama feathers. Lastly, Sinornithosaurus simply lived too late to have anything to do with feather origins. In sum, this paper is interesting speculation, but little else."


**********************************************************
From: "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>
Reply-To: tholtz@geol.umd.edu
To: "dinosaur" <dinosaur@usc.edu>
Subject: Martin on Sinornithosaurus feathers
Date: Thu, 15 Mar 2001 09:56:41 -0500

Greetings,

For those interested, I have come across the first reference so far from the
anti-dinosaurian origin of birds group. In an online Science News article
(URL is:
http://sciencenow.sciencemag.org/cgi/content/full/2001/307/3) (you may need
an online subscription to Science to see this: I'm not certain), Martin
states:


"They certainly do not tangle like wet down feathers."

As far as I've seen, that is it from Martin and the BAND.

              Thomas R. Holtz, Jr.
              Vertebrate Paleontologist
Department of Geology          Director, Earth, Life & Time Program
University of Maryland         College Park Scholars
              College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone: 301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661      Fax (CPS-ELT): 301-405-0796
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