Important new fossil
Robin Mandell (rmandell@jpusa.chi.il.us)
Tue, 26 Jan 1999 16:22:37 -0600
Hi list, if this was posted already I missed it. Kinda interesting
>
>The New York Times, January 26, 1999, Tuesday, Science Desk
>HEADLINE: Turning Dinosaur Theory on Its Paleobiological Tail
>BYLINE: 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.
> 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, S.C, 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.
> Dr. 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 Dr. 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, Dr. 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, Dr. 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 Dr. 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, Dr. 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, Dr. 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," Dr. Feduccia said.
> But Dr. Lawrence Witmer, an evolutionary biologist at Ohio
>University's College of Osteopathic Medicine in Athens, was one of the
>experts who challenged Dr. 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," Dr. 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 crocodile-like systems?
>The history of life has often confounded theory."
> He said that Dr. Ruben's ideas might turn out to be correct, but that
>further evidence was needed to settle some large doubts.
> Dr. 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."
>
>GRAPHIC: Chart/Photo: "A Revealing Link to the Past"
>Researchers are looking to an exceptionally well preserved fossil of a
>young Scipionyx, a small meat eating dinosaur, to answer questions about
>the nature of the species.
>Leg Muscles -- Preserved tissues run from the pelvis to the upper legs.
>The creature appears to have been capable of bursts of great speed.
>Colon -- It's position, high and close to the spinal column, is similar
>to the position of the colon in crocodiles.
>Liver -- It's location in the abdominal cavity suggests and arrangement
>of organs more similar to crocodiles than birds.
>
>
>