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Re: Feduccia et al: No Evidence Fossil Feathers Are Really Feathers



Roberto Takata (rmtakata@gmail.com) wrote:

<Okay, _Caudipteryx_ caudal "feathers" is a supporting tissue that resemble
feathers to a *modest* degree?>

  It goes beyond that, but that's it essentially. That or *Caudipteryx*, as
predicted by Jones et al., is a bird. Ooooo.

  Two years ago, Lingham-Soliar used an ichthyosaur fossil and a shark
dissection to show overlying layers of collagen fibers creates an imbricating
pattern with faint under-fibers, strong over-fibers showing the layering and a
matched by angled pattern on the otherside of a division. He interpeted this as
evidence of a flap of collagen fibers in the skin being lifted up and lain
flat, or folded over, creating a "rachis" and "vanes". This is pretty damning
to the theory of feather preservation. The problem with this is twofold: 1) the
layering was obvious on both sides in the sampled tissues, but mainly in the
ichthyosaur, and 2) the evidence for producing a "vane" with a single "rachis"
was actually a strong fiber overlying a bed of weak fibers. The fossil evidence
for this shows a general alignment of all fibers in nearly the same orientation
over a bed of perpendicular fibers (i.e., the layers are imbricating). They do
not look like a vane, but this is a subjective interpretation of my own. 

  In the new paper, Feduccia et al. expand their data set to include some
terrestrial animals, rather than thick-fleshed, "net-skinned" animals (a
feature that has been linked in dolphins to improving the skin's resistance to
water flow and controlling the tubular body and is seen in the shark samples
but more importantly in scombrid fish (including tuna) ... see Pabst, D. A.
2000. To bend a dolphin: Convergence of force transmission designs in cetaceans
and scombrid fishes. _American Zoologist_ 40(1):146-155.)

  It argues that densely arrayed collagen fibres in Lingham-Soliar's
ichthyosaur are probably due to the THICK tissue layers between the surface of
the skin and skeleton that control the body shape and essentially enable it to
swim better. The perfect model for skin in terrestrial vertebrates? I think
not.

  So this leads us to the densely arrayed patterns in *Caudipteryx* remiges and
retrices, as well as those in a juvenlie specimen of *Sinornithosaurus*
("Dave") which Feduccia et al. claim exhibit the skin fibre condition of
non-featheredness, this despite later claiming that microraptors are avian
non-theropods (and missing that *Sinornithosaurus* is a microraptor based on
their own --earlier -- osteological evidence for avian identity, using Paul's
identification of the mdII-1 [my shorthand for the first phalanx of the second
manual digit] lateral flange). Here, these fibres are long, tapered, and
isolated from one another. But using "Dave" in which the thigh feathers are
apparently dense enough to show mild overlapping, they are separated tissues.
So, I ask, how did they get this way? Did minute layer of collagen get
separated via dessication one at a time, but eroding the underlying later to
preserve only the "rachis" and "vanes"? And why in "Dave" are these tissues
_impressions_? Yet *Microraptor* is unquestionably avian, because it "looks"
like it has wings.

  My only response is that if Lingham-Soliar are correct, then the tissue
structure shows that not just vanes of flesh and not feathers exist, but that
these animals are in fact marine and enclosed by a (now dessicated) tubular
fleshy structure and were in fact thunnoid in structure, as the dense tissues
MUST be collagenous packed layers that were flattened as the animal died, but
left only around the arms, legs and tail, and the rest were small fins of flesh
(around "Daves" head, an iguana crest!) or enclosed the head in a tube of
blubber.

  Perhaps my response to Lingham-Soliar (2003) is a bit late, but this paper
made me see that the obvious conclusion has not only been reached by the
author's but overlooked by them in the same breath, and never mentioned.

  Lingham-Soliar's papers on the topic, btw:

  Lingham-Soliar, T. 1999. Rare soft tissue preservation showing fibrous
    structures in an ichthyosaur from the Lower Lias (Jurassic) of England.
    _Proceedings of the Royal Society of London_, B 266:2367?2373.
  ______ 2001. The ichthyosaur integument: skin fibers, a means for a strong,
    flexible and smooth skin. _Lethaia_ 34:287?302.
  ______ 2003a. Evolution of birds: ichthyosaur integumental fibers conform to
    dromaeosaur protofeathers. _Naturwissenschaften_ 90:428?432.
  ______ 2003b. The dinosaurian origin of feathers: Perspectives from dolphin
    (Cetacea) collagen fibers. _Naturwissenschaften_ 90:563?567.

  And Pabst's paper cited above, as I checked, is available online, just use
scholar.google.com for all your pdf shopping needs. Cetaceans, as predicted by
Star Trek, really are the keys to the future!

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
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