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CNN: fossil shows dinosaurs were supercharged
Fossil Shows Dinosaurs Were ''Turbocharged''
WASHINGTON, Jan 21 (Reuters) - Meat-eating dinosaurs may have been
technically reptilian, but they could run fast enough and long enough to
chase down any prey they wanted, researchers said on Thursday.
Studies on the fossilized remains of a baby dinosaur found in Italy show
it probably was cold-blooded like a reptile, but had the metabolic
capacity of a modern mammal or bird.
"These theropod (meat-eating) dinosaurs were fast, dangerous animals,
certainly not slow or sluggish," Nicholas Geist of Oregon State
University, who worked on the study, said in a statement.
"They could conserve energy much of the time and then go like hell when
they wanted to. That might go a long way toward explaining why they were
able to dominate mammals for 150 million years."
The researchers, working with a team at the Museo Civico di Storia
Naturale in Milan, reported their findings in the journal Science.
A variety of studies are beginning to show that dinosaurs, at least the
meat-eaters, were not the pondering, slow-witted creatures that people
thought they were.
"If you could go back in time and saw one of them, that's probably the
last thing you'd ever see," Geist said.
John Ruben, who also worked on the study, noted that reptiles such as
crocodiles can move quickly in short bursts.
"They can sprint," he said in a telephone interview. "The difference is
that warm-blooded animals (such as birds and mammals) can maintain this
for a lot longer. They have a lot more stamina. And that is what we are
saying the theropod dinosaurs had."
So they would be as quick and ruthless as a crocodile, with the stamina
of a modern-day carnivore such as a lion.
"What you have is a turbocharged reptile," Geist said.
The researchers developed their theory after looking at very
well-preserved remains inside the chest of a baby Scipionyx, a dog-sized
predator similar to the velociraptors made famous in recent dinosaur
fiction films such as "Jurassic Park."
"In that animal, under visible light, you can see distinct visceral
organs like the intestines, the liver," Ruben said.
"But under ultraviolet light, the thing just literally started to glow.
The intestines were much more visible, the liver became more visible,
the muscles as they were preserved were more visible."
The layout was like that of a creature that breathes with a diaphragm,
like humans and other mammals do. That implies a breathing capacity much
greater than that seen in most living reptiles.
If dinosaurs were cold-blooded, that could explain why they died out 65
million years ago, Ruben said.
"If these things are ectotherms or cold-blooded, they depend on the
environment for their body temperature," he said.
"They are not maintaining body temperature because of a high metabolic
rate like we do."
That would be fine in the relatively warm climate of the Cretaceous and
preceding periods. But the climate changed, going through much cooler
periods and even ice ages.
Even a little cooling could have been enough to wipe out the dinosaurs,
even before an asteroid hit and kicked up dust, as many scientists now
think happened 65 million years ago, Ruben believes.
"Dinosaurs were beginning to lose diversity and disappear a good six to
eight million years before the asteroid hit," Ruben said.
"They were on the way downhill for a long time. I would suggest that
one reason might be that these were very highly specialised cold-blooded
animals that could not survive easily in an environment that was
becoming seasonally cooler."
Copyright 1999 Reuters Limited.All rights
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