Re: News: New feathered dinosaur specimen strengthens dino-bird link.

On Fri, 25 Sep 2009 15:11:47 -0700, John Harshman
<jharshman@xxxxxxxxxxx> wrote in
<RcGdnZTgXte53SDXRVn_vwA@xxxxxxxxxxxx> :

Ye Old One wrote:
Sep 24, 2009 05:45 PM in Biology

New feathered dinosaur specimen strengthens dino-bird link

By Katherine Harmon in 60-Second Science Blog

http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=new-feathered-dinosaur-specimen-wea-2009-09-24

First off: yawn. Might as well say "New pregnancy test strengthens
sex-baby link".

Ouch!


Nonavian dinosaurs are long extinct, but paleontological thinking
about them, especially the dino?bird specimens, clearly continues to
evolve long after they are discovered. For instance, the Anchiornis
huxleyi, a small, feathered dinosaur, was described last December and
assumed to be a transitional species that existed between dinosaurs
and birds. But new evidence?and a much better specimen?has revealed
that this ambiguous animal actually belongs to the dinosaur clan.

Urk.

Described from a partial specimen in the Chinese Science Bulletin, A.
huxleyi was proposed to be an "intermediate?between nonavian and avian
dinosaurs," wrote Xing Xu, a paleontologist at the Institute of
Vertebrate Paleontology and Paleoanthropology at the Chinese Academy
of Sciences in Beijing, and his colleagues. But as a dinosaur?now
proposed to be a troodontid, a birdlike group of theropods?it sets the
clock back for bird evolution.

Also urk.

The dinosaur?bird transition has been the subject of debate for more
than a century, and some researchers are still arguing that other
birdlike dinos are too recent to be the ancestors of birds. The
quandary, known in the paleontology field as the temporal paradox,

It's not a quandary to anyone except Alan Feduccia and a couple of his
buddies. All other paleontologists realize how silly it is. It is, in
fact, the exact equivalent of "If we came from monkeys, why are there
still monkeys?"

has
been dealt another blow by the reassessment of the A. huxleyi, which
is dated to about 155 million years old?about 30 million years before
the feathered dinosaur Microraptor and about five million years before
the oldest known bird, Archaeopteryx. This earlier date for the
emergence of feathered dinosaurs undermines claims that birds lacked
enough time to evolve from dinosaurs.

No it doesn't, because those claims were never credible. I recommend, as
a corrective to any readers who wonder about this, the following paper:
Brochu, C. A., and M. A. Norell. 2000. Temporal congruence and the
origin of birds. Journal of Vertebrate Paleontology 20:197-200.

Or, if your library is an extensive one, there's

Brochu, C.A., and M.A. Norell, 2001. Time and trees: A quantitative
assessment of temporal congruence in the bird origins debate. pp.
511-535 in J.A. Gauthier and L.F Gall (eds.), New Perspectives on the
Origin and Early Evolution of Birds, Peabody Museum of Natural
History, New Haven, CT.


You will note that it's 9 years old, and it shouldn't have been
necessary even then.

In addition, the research "sheds new light on the early evolution of
feathers and demonstrates the complex distribution of
skeletal?features close to the dinosaur?bird transition," the paper
authors write [pdf] in the letters section of Nature this week
(Scientific American is part of the Nature Publishing Group).

That's press release hype. A feathered troodont sheds no light that the
previous feathered dromaeosaurs, oviraptorosaurs, and compsognathids
didn't shed already.

Well, I don't know about that. While the remiges are curved, they're
also symmetrical, and the outline of the wing is a bit different from
that of Microraptor and Archaeopteryx (the longest feathers originate
from the area of the wrist), which leads me to think that Anchiornis
is close to the origin of gliding.


Adding lift to the theory that these animals once flew or glided with
all four wings, the A. huxleyi appears to have had several contour
features (aka pennaceous feathers)?found on modern birds?on its hind
legs. The authors of the most recent paper, to which Xu also
contributed, note that this supports the idea that feathers developed
first on the tail region of dinosaurs and spread later to the
forewings, before disappearing from the legs of contemporary birds.

Conceivably this is actually something new. Depends on what the Nature
paper really says, and whether this troodont has flight feathers on its
forelimbs too.

You can read it here:
http://www.nature.com/nature/journal/v461/n7264/pdf/nature08322.pdf


Both specimens were unearthed in the Tiaojishan Formation in Liaoning,
China. The small dinosaur originally described in the Chinese Science
Bulletin measures about 34 inches long and weighed about 110 grams.
Although it might have played a part in ushering in a brave new world
for birds, the A. huxleyi is named not for the famed science-fiction
author, but for Thomas Henry Huxley, an early advocate of evolution
and one of the first people to suggest that birds may indeed be
descended from dinosaurs.

Well, duh. And Aldous Huxley was a science fiction author? For one book?

.

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