On Tue, 27 Jan 1998 13:50:18 -0600, Kevin Koenig wrote:
[...]
>SJ>Interesting, scientific journals take a few weeks to get out to
>the antipodes, but I saw the following brief report on the web at
>http://www.nature.com/Nature2/serve?SID=5125902&CAT=TOC&PG=19980101 /
>toc.html (you will have to sign on for a free subscription):
I have now read the Nature and Science articles regarding this. The
pictures do not look anything like feathers to me. This is exactly
the same dinosaur, Sinosauropteryx, of which an earlier article in
SCIENCE had said:
"When John Ruben first laid eyes on a high-quality photo of the so-
called "feathered" dinosaur from China last year, he was stunned. It
wasn't the featherlike structures that riveted his attention-he
dismissed them as collagen fibers..." (Gibbons A., "Lung Fossils
Suggest Dinos Breathed in Cold Blood", Science, Vol. 278, 14
November 1997, p1229)
>KK>I mentioned the two articles that appeared in Nature because
>both mentioned "integumentary structures." The article,
>"Feathers, filaments and theropod dinosaurs" it mentions
>"Although few scientist have yet seen the fossil material, some are
>already incorporating Sinosauropteryx into models for the origin of
>feathers and bird flight."
All the Western paleontologists who have actually seen the
Sinosauropteryx fossils, including the palaeontological "dream team"
which examined the earlier Sinosauropteryx fossil, concluded that the
fibres were not feathers:
"The Sinosauropteryx specimen from the Yixian Formation in China
made the front page of The New York Times, and was viewed by
some as confirming the dinosaurian origins of birds. But at this year's
vertebrate paleontology meeting in Chicago late last month, the
verdict was a bit different: The structures are not modern feathers,
say the roughly half-dozen Western paleontologists who have seen
the specimens. The stiff, bristlelike fibers that outline the fossils lack
the detailed organization seen in modern feathers, says Alan Brush,
an ornithologist at the University of Connecticut Storrs, who
specializes in feather structure. Brush was part of a "dream teams
sent to China this spring by The Academy of Sciences in Philadelphia
to view the fossils." (Gibbons A., "Lung Fossils Suggest Dinos
Breathed in Cold Blood", Science, Vol. 278, 14 November 1997,
p1229)
Also, another group of Chinese researchers do not claim that they
are feathers:
"...Ji Qiang, director of the Chinese Geology Museum in Beijing,
insists that the fibers are "obvious primitive feathers." But a paper in
press at Nature by another group of Chinese researchers doesn't make
that claim, says Currie." (Gibbons A., "Plucking the Feathered
Dinosaur", Science, Vol. 278, 14 November 1997, p1229)
>KK>In the article, An exceptionally well-preserved theropod dinosaur
>from the yixian Formation of China" Feathers are not mentioned
>until the "discussion" portion of the article. "The integumentary
>structures are extremely interesting regardless of wether they are
>referred to as feathers, protofeathers or some other structure."
>KK>In my opinion I think it is safe to say that this new fossil represents
>co-evolution. Personally I equate this fossil to something similar to
>bats, flying lemurs and flying squirrels. Like these animals
>Sinosauropteryx may have evolved to fill an empty niche.
There is no suggestion in any of the articles that Sinosauropteryx
flew. So I cannot see how they were "similar to bats, flying lemurs
and flying squirrels", and fill the "empty niche" that these mammals
were later to fill.
>KK>I don't think it discredits the evolution of birds from reptiles either. I
>suppose one could use this fossil as a model as to how feathers
>*might* of evolved. (I am not familiar to genetic studies comparing
>scales and feathers. I learned something from this.)
The genetic evidence is that in just about every feature at the molecular
level, reptilian scales and feathers are not related:
"It has been a truism for most of this century that feathers are related
to reptilian scales. Various authors have argued that feathers are
derived directly from reptilian scales or possibly tubercles (Thulborn,
1987). It almost goes without saying that the scales on birds must
also be homologous to reptilian scales. If this homology exists then
one would expect similarities at all levels of organization....The
molecular evidence questions the simple, direct relation of the
specialized statures of birds to reptile scale. I will provide arguments
to show that reptilian scales and feathers are related only by the fact
that their origin is in epidermal tissue. Every feature from gene
structure and organization, to development, morphogenesis and tissue
organization is different. I believe that while there is phenotypic
similarity in some scales, that feathers are unique to birds and deserve
consideration as an evolutionary novelty." (Brush A.H., "On the
origin of feathers," Journal of Evolutionary Biology, 9, 1996, p132)
>KK>I thought the second article, An exceptionally well-preserved
>theropod dinosaur from the yixian Formation of China, was the
>more interesting as it sought to only describe this new find and
>then present ideas in the discussion portion.
In its abstract, all the article claims is that "Both specimens have
interesting integumentary structures that could provide information
about the origin of feathers." (Chen P-j, Dong Z-m & Zhen S-n, "An
exceptionally well-preserved theropod dinosaur from the Yixian
Formation of China", Nature, vol. 391, 1998, p147)
Also, it points out that there is a Spanish theropod which has
similar fibres:
"Integumentary structures have also been reported in the theropod
Pelecanimimus 24 from the Lower Cretaceous of Spain. These
consist of subparallel fibres arranged perpendicular to the bones, with
a less conspicuous secondary system parallel to them. As described,
they seem to be similar to the integumentary structures of
Sinosauropteryx." (p151)
and that:
"...much more work needs to be done to prove that the integumentary
structures of Sinosauropteryx have any structural relationship to
feathers, and phylogenetic analysis of the skeleton clearly places
compsognathids far from the ancestry of birds." (p152)
>KK>Even in the discussion (I thought well written BTW) it mentioned "
>... feathers, protofeathers, or some other structure." Indeed the
>way these integumentary structures are described I thought of the
>hollow shafted hairs that polar bears possess or hairs like those of
>a hedgehog or, from Stephen's own continent, the hairs of an
>Echidna.
This is exactly the point. There are many animals which have unusual
integumentary structures. For years evolutionists have been claiming
that reptile scales are proto-feathers:
"One of the classic arboreal scenarios was developed by Gerhard
Heilman in his well known book The Origin of Birds. Heilman, as an
advocate of the arboreal theory, envisaged a gliding stage preceding
the development of true powered flight. The original ancestor, he
suggests, was a terrestrial runner: `By the friction of the air, the outer
edges of the scales become frayed, the frayings gradually changing
into still longer horny processes, which in course of time become
more and more featherlike, until the perfect feather is produced. From
wings, tail and flanks, the feathering spreads to the whole body."
(Heilman G., "The Origin of Birds", 1926, pp200-201) (Denton M.,
"Evolution: A Theory in Crisis", 1985, p204)
>KK>I'm not implying that they are hairs or that Sinosauropteryx is
>somehow related to mammals. I'm saying the integumentary
>structures are similar to those I mention above. From these
>observations I can say that the filamentous structures do not
>necessarily have to be protofeathers but rather an adaptation of
>some sort.
I thought Unwin's article was appropriately sceptical:
"This brings us to the critical question: are these structures some kind
of 'protofeather'?...any argument for homology between the feathers
of birds and the integumentary structures of Sinosauropteryx needs to
be supported by more than general similarities in structure and
position. High- resolution microscopy and biogeochemical tests might
provide some answers, but they will not solve all of the problems.
Moreover, if Sinosauropteryx bears proto-feathers, we might expect
similar (or perhaps even more feather-like) structures to have been
present on at least some of the- theropods that are more closely
related to birds than is Sinosauropteryx (Fig. 2). Exceptionally well-
preserved remains of the integument are now known for two of these
dinosaurs-the ornithomimosaur Pelecanimimus", and a small,
unnamed maniraptoran theropod from Brazil 12. In both cases,
however, there is no evidence of the filamentous structures found in
Sinosauropteryx." (Unwin D.M., "Feathers, filaments and theropod
dinosaurs", Nature, vol. 391, 1998, pp119-120)
I repeat that I would have no problem if it could be shown that
birds originated from theropods like Sinosauropteryx, but it
seems to me that there are a number of problems to be solved
first before it can be said that they did.
God bless,
Steve
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Stephen E (Steve) Jones ,--_|\ sejones@ibm.net
3 Hawker Avenue / Oz \ Steve.Jones@health.wa.gov.au
Warwick 6024 ->*_,--\_/ Phone +61 8 9448 7439
Perth, West Australia v "Test everything." (1Thess 5:21)
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