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New York Times Feature on Scipionyx debate



Here's a feature article on that coldblooded supercharged lizard,
_Scipionyx samniticus_:

Copyright 1999 The New York Times, acknowledged.

                    *  *  *

January 26, 1999


Turning Dinosaur Theory on Its Paleobiological Tail

By MALCOLM W. BROWNE

By shining ultraviolet light on the fossil of a baby dinosaur that had
collected dust in a file drawer in Italy for 15 years, paleontologists
have discovered astonishingly well-preserved anatomical details that
have rekindled one of the most intense debates in paleobiology. 

The discovery has cast doubt on two widely held theories: that
dinosaurs were warmblooded and that they were the ancestors of birds. 

(interesting point-and-click illustration of Scipionyx located here:
check out the Times' website to see this)

Many paleontologists in recent years have come to accept the theory
that at least some dinosaurs could maintain steady body temperatures
by themselves. Many paleontologists are also convinced that birds are
closely related to dinosaurs, probably as their direct descendants.
Part of the evidence for this is the striking similarity of the
skeletons of some dinosaurs to those of birds. 

The baby dinosaur recently examined was first found embedded in a
limestone formation north of Naples in 1983. Last year, after its
rediscovery in the Archeological Administration in Salerno,
paleontologists who examined it were astonished to find that much of
its flesh, including many of its internal organs, had been preserved
in fossil form -- an extraordinary discovery. The unique fossilized
dinosaur, named Scipionyx samniticus, has by far the best preserved
fossil organs of any dinosaur ever found, scientists agree. 

Since the initial investigation, which was reported a year ago, a team
of paleontologists headed by Dr. John A. Ruben of Oregon State
University at Corvallis and Dr. Willem J. Hillenius of the College of
Charleston, in South Carolina, has examined the fossil under
ultraviolet radiation. On Friday, the journal Science published the
result: a spectacular picture in fluorescing colors, in which the
little animal's organs stand out as vividly as color-coded engineering
diagrams. 

"It's amazing," said Dr. Larry Martin, a paleontologist at the
University of Kansas. "It's essentially a dinosaur that's been
dissected." 

Paleontologists who have seen the ultraviolet pictures of Scipionyx
agree that they are uniquely revealing. But experts are far from
agreeing on the interpretation of the images. 

Ruben and his colleagues argue that the fossil provides strong
evidence that dinosaurs had a breathing mechanism similar to that of
modern crocodiles and completely different from that of birds. From
this and some other evidence, they deduced that theropod ("beast
footed") dinosaurs, including the mighty Tyrannosaurus rex, were
coldblooded, but were capable of spurts of intense activity. 

A member of Ruben's group, Nicholas R. Geist, said, "What you have is
a turbocharged reptile." 

Scipionyx, which in life probably somewhat resembled the fierce
velociraptors depicted in the movie "Jurassic Park," lived about 110
million years ago. This specimen, an infant that apparently died
shortly after it was hatched, failed to attract much scientific
interest at the time it was found. 

But it was later discovered that its different body parts were
selectively mineralized by different chemicals in the marine sediments
in which it was buried. This causes the fossilized organs to fluoresce
in different colors when exposed to ultraviolet. 

The animal's colon glows bright yellow and appears to lie very close
to its spinal column. In modern reptiles, the colon is arranged like
this only in crocodiles, Ruben said. 

In another possible similarity with crocodiles, scientists found
evidence in the infant dinosaur of a specialized breathing device
called a hepatic piston. In the crocodile, Ruben said, the piston is a
large liver driven by muscles that pull it in and out to move air
through the lungs. The colon lies near the crocodile's spine to leave
room for the liver to move freely. 

Scipionyx's lungs themselves were not preserved, but Ruben identified
a large organ that glows blue under ultraviolet light as its liver.
The relative positions and sizes of these and other organs mark them
as crocodilian in type, he said. 

By contrast, Ruben said, a bird's colon extends right through the
middle of its abdominal cavity. 

"It seems clear," he said in an interview, "that a bird's radically
different system of breathing, in which air is continuously drawn
through its lungs, could not have evolved from the hepatic-piston
system we see in this theropod dinosaur." 

The indications, however faint, that Scipionyx had diaphragmatic
muscles to assist its liver piston in breathing suggest that the
animal may have been an ectotherm (coldblooded), but was capable of
sustaining oxygen consumption rates and activity levels beyond those
of modern reptiles, Ruben said. 

These views were strongly endorsed by Dr. Alan Feduccia, an
ornithologist at the University of North Carolina, who has long argued
that birds could not have descended from dinosaurs. 

"I think John Ruben has done a remarkable job -- a nice piece of
detective work on a beautiful specimen," Feduccia said. 

But Dr. Lawrence Witmer, an evolutionary biologist at Ohio
University's College of Osteopathic Medicine, in Athens, Ohio, was one
of the experts who challenged Ruben's conclusions. 

"We have a ton of evidence for the view that birds descended from
theropod dinosaurs, and John Ruben's conclusions fly in the face of
this abundant evidence," Witmer said. 

"He raises some intriguing points," he added, "but I'm not convinced
that we're really seeing a hepatic piston in this fossil. Remember,
we're seeing it in crushed form. Also, how do we know that bird
breathing systems could not have evolved from crocodilelike systems?
The history of life has often confounded theory." 

He said that Ruben's ideas might turn out to be correct, but that
further evidence was needed to settle some large doubts. 

Martin, of the University of Kansas, suggested, however, that the
evidence already appeared to be in hand. 

Regarding the conclusions of the Oregon State University team, he
said: "There's actually no way they could be wrong about this. The
Scipionyx specimen has the best preservation ever seen. It's one of
the biggest discoveries of this decade. It tells us more about
dinosaurs than any other specimen. 

"The positions of the dinosaur's windpipe and colon serve as
independent checks that the animal did not have a bird's breathing
apparatus," he said. And, he said, the external shape of theropod
dinosaurs, "with deep, narrow body walls, is exactly the design you
would expect for an animal with a hepatic piston." 

As for the scientists who hold to the bird-dinosaur connection, he
said: "They're really cast in stone. Despite this new evidence, it's
going to be very hard for them to change their minds now." 

                       *  *  *

==
Larry
"You are interested in the unknown, the mysterious, the unexplainable -- that 
is why you are here.  And now, for the first time, we are bringing you the full 
story of what happened ... on that fateful day."
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