Fossil Reptiles' Feathers Debated (AP)

[Larry Dunn <majestic_cheese@yahoo.com>]

Here's an AP story about a paleofeather controversy,
on a day that Americans' minds turn to a different
feathered creature.

                          *  *  *

Fossil Reptiles' Feathers Debated

By THE ASSOCIATED PRESS
Filed at 6:07 p.m. ET

Feathers or scales? Scientists analyzing a 220
million-year-old reptile fossil can't agree on what
they're looking at.

Earlier this year, researchers suggested that a small,
lizard-like reptile known as Longisquama was studded
with long feathers that enabled it to fly, or at least
glide. Their interpretation would push back the
ancestry of modern birds by 75 million years.

Now, a rival scientific team from Canada reports that
the notion of an airborne Longisquama is too flighty.

What appear to be feathers poking from the reptile's
spine actually are long, thick scales that left
cup-like impressions in surrounding rock, the
Canadians conclude in the current issue of Nature.

Hardly dainty, they said the body armor scales may
have attracted mates or frightened predators.

``Feathers are extremely paper-thin structures, but
these have some depth to them, a real substantial
three dimensional nature. It's completely unlike bird
feathers,'' said zoologist Hans-Dieter Sues of the
University of Toronto.

He and co-author Robert R. Reisz argue that the fine
details do not support the feather interpretation.

A quill-like structure is only a furrow running the
length of the scale, he said. And, the feathery barbs
running perpendicular to the ``quill'' really is a
corrugated pattern on the scale.

Feather advocates dismissed the Canadians' scale
interpretation as ``total nonsense.''

Oregon State paleontologist John Ruben, who
co-authored the original Longisquama study, said the
Canadian scientists based their conclusion on the
worst-preserved of all the Longisquama fossils -- one
that was clogged with petrified sediment.

The best fossils, he said, clearly show the creature's
long appendages possess a concave-convex structure
consistent with the bowed appearance of modern
feathers.

And, the quill-like structure on the fossil analyzed
by the Canadians had deteriorated and flattened out.
Other fossils show the quill in sharp relief, he said.

Longisquama was discovered in central Asia in 1969. It
is thought to be an archosaur, a member of a reptile
group that later gave rise to dinosaurs, crocodiles
and birds.

If Ruben's analysis is correct, it challenges the
premise that birds arose from small, meat-eating
dinosaurs. The earliest known bird, Archaeopteryx,
appeared about 145 million years ago -- some 75
million years after Longisquama.

Alan Feduccia, an evolutionary biologist at the
University of North Carolina, Chapel Hill, believes
the appendages on Longisquama may have been a
transitional structure between scales and feathers.

``Since we know that scales and feathers are closely
related, it makes sense that we would eventually find
something like this,'' Feduccia said.



=====
Larry

"Catapultam habeo. Nisi Pecuniam omnen mihi dabis ad capul tuum saxum immane 
mittam."

http://members.tripod.com/~megalania/index.html

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