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AP story on Scipionyx



Here's AP's take on the "Scipionyx" story.  So, opininos have changed
on this critter?  Last I heard people were leaning toward it being an
infant of a garden variety large carnivore.

                       *  *  *

Fossils Suggest Dinosaurs Were Fast

Filed at 8:24 a.m. EST

By The Associated Press
WASHINGTON (AP) -- A well-preserved fossil of a 110-million-year-old
baby dinosaur suggests that the extinct animal had the lungs to be a
swift and deadly hunter, researchers say in a new study. 

Nicholas Geist, a paleobiologist at Oregon State University, said the
remains of a specimen called Scipionyx may be the best preserved
dinosaur fossil ever found and will provide researchers with new
insights into the extinct animals. 

``The extraordinary condition of the fossils allows us to hang some
meat on the bones of these animals,'' said Geist, the senior author of
a study appearing today in the journal Science. 

``What you usually get in fossils is just bones, but in this one there
are remnants of liver, large intestine, windpipe and muscle,'' he
said. ``It is like a Rosetta stone for dinosaurs.'' 

Scipionyx was a theropod, a type of meat-eating dinosaur that walked
on its hind legs, had a big head with a large mouth and teeth, a long
tail and small forearms. 

Geist said the soft tissue impressions show that the Scipionyx had a
two-partition abdominal cavity, with the lungs and heart in one
section, and the liver and guts in the other. The liver was connected
by muscle to a pelvic bone, he said, suggesting that the animal had a
breathing system called a hepatic piston. 

In such a system, muscles pull against the liver, causing the
breathing cavity to expand slightly. This forces air into the lungs at
high rate. 

``This is necessary for sustained activity,'' said Geist. ``These
theropods were exceedingly fast and dangerous animals. They were not
slow and sluggish like many modern reptiles. They could go like hell
whenever they wanted to.'' 

Mammals have a diaphragm muscle that causes the lung cavity to expand
and draw in air. The ability to rapidly ventilate the lungs is
essential for moving swiftly for long periods. 

This lung capacity may be one reason that dinosaurs dominated mammals
for about 150 million years, said Geist. Mammals during this period
were small and no match for the meat-eating dinosaur. 

``These dinosaurs were fierce animals that could run prey down over
extended distances and definitely not the sort of sluggish movers of
many living reptiles,'' Geist said. ``This was like a turbo-charged
lizard. The mammals couldn't get a foothold and just tried to stay out
of the way.'' 

Geist said the hepatic piston works best in a warm, mild climate such
as the Earth enjoyed during most of the dinosaur era. When the climate
chilled, the dinosaurs were in trouble. 

``These animals may have been so specialized for the warm climate,
that even a minor change over an extended period may have helped do
them in,'' he said. 

``The interpretation of this fossil makes this animal more like the
popular idea of the dinosaur, such as in the movie 'Jurassic Park',
that they were fast and agile and able run for some distance,'' said
Terry D. Jones, a co-author of the study. ``This gives some credence
to that idea.'' 

Not all experts agree that the Scipionyx fossil gives such precise
evidence of a hepatic pump breathing system, said Paul Soreno, a
dinosaur expert at the University of Chicago. 

``For many in the field, that interpretation is controversial,'' said
Soreno. 

The Scipionyx fossil, the only dinosaur ever found in Italy, is small
enough to hold in two hands and the animal may have been only days old
when it died. Geist said it perished in a saltwater marsh which
preserved its body structure. 

No fossil for an adult Scipionyx has been found and Geist said the
animal species probably grew to only about the size of a large dog. 






==
Larry

"Glass of milk
Standing in between extinction in the cold
And explosive radiating growth"

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