Reflectorites
I regret that onwing to pressure of study, I am unable to continue with
my posting of a wide range of extracts of articles posted on various
science news type pages.
In future I will just post single news articles, sometimes with my
comments in square brackets.
I have noticed BTW that many such articles are now including
"Emai this story..." just before their copyright notice. This seems
to indicate that they have no problem with non-commercial
reproduction of their pages.
Here is an interesting article on a dinosaur fossil which revealed
under CT scanning to have "a four-chambered, double-pump heart
with a single systemic aorta, more like the heart of a mammal or bird
than a reptile," which is interpreted to mean it was warm-blooded.
I don't know enough to disagree about whether such a heart means
it necessarily was warm blooded or whether it simply means that
a large land animal requires such a heart, whether warm-blooded
or not.
Steve
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http://dailynews.yahoo.com/h/nm/20000420/sc/science_dinosaur_1.html
[...]
Yahoo!
Thursday April 20 3:58 PM ET
Images Show Warm Side of Dinosaur Hearts
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Surprise images of the insides of a 66 million-
year-old dinosaur show it had the heart of a warm-blooded animal, adding
to evidence that dinosaurs were not slow and plodding but quick and
hungry, scientists said on Thursday.
They used a computed tomography (CT) scan on a fossil nicknamed
"Willo" to show the 66 million-year-old dinosaur had a four-chambered
heart more akin to a human than to a lizard. CT scans use X-rays and
computer software to "peel away" layers of tissue, or in this case layers of
dirt and fossilized bone, to image inside a body.
The scientists' report, published in the journal Science, describes how they
used the X-ray technology developed for use by doctors to peek inside the
ancient fossil.
[...]
"Not only does this specimen have a heart, but computer-enhanced images
of its chest strongly suggest it is a four-chambered, double-pump heart
with a single systemic aorta, more like the heart of a mammal or bird than a
reptile," Dale Russell, a paleontologist at North Carolina State University
who helped coordinate the study, said in a statement.
The fossil, on display at the North Carolina Museum of Natural Sciences,
was dug up in 1993 in South Dakota. It was exceptionally well-preserved,
so the researchers decided to look at it using CT scans.
"We have been doing pieces of dinosaurs off and on for a long time, mostly
looking for internal bony structures or bones damaged in some way like a
fight," Paul Fisher, director of the university's veterinary Biomedical
Imaging Resource Facility, said in a telephone interview.
"It's A Heart"
"This was the first time we were looking for what used to be soft tissue
structures."
Fisher said they did not know what they would find.
"We were surprised that it is as recognizable as it is -- something that had
been in the ground for 65 to 67 million years," Fisher said. "We did not
think we would put it together in a 3-D model and say, 'Oh my God -- it's a
heart'. It is one of those things where a picture is worth a thousand words."
The study could transform the way paleontology is done. Until now,
researchers have had to rely on little more than bones, and perhaps the
imprint of a feather or some skin in rock, to tell how ancient creatures
looked.
But in some fossils, soft tissue may remain in a form accessible to CT
scans.
Ironically, this soft tissue looked like dirt to early paleontologists, who
scraped it away to reveal bones for study and display, Fisher said.
Evidence from bones alone at first suggested that dinosaurs were big
reptiles. Reptiles are cold-blooded and rely on the sun and outside
temperature to warm up their bodies enough to move. They do not eat as
often as mammals, which can regulate their own body temperature and
have a faster metabolism.
Scientists have had hints, however, that dinosaurs might be more akin to
mammals and to birds -- which many believe to be the living descendants of
dinosaurs.
In January 1999, U.S. and Italian researchers used ultraviolet light to peer
inside the chest of a fossil baby dinosaur and found its organs were laid out
like a bird's or mammal's.
'Challenges Fundamental Theories"
And other researchers looking at fossilized bones of dinosaurs have found
suggestions that they had many blood vessels inside, again indicative of a
warm-blooded metabolism.
But no one had hoped for such conclusive evidence.
"It's truly amazing that this animal seems to have had such a highly evolved
heart. The implications completely floored me," Russell said.
"This challenges some of our most fundamental theories about how and
when dinosaurs evolved." Reptiles have three-chambered hearts and
evolved long before mammals. The specimen itself is a member of the
Thescelosaurus genus, weighed about 660 pounds and was 13 feet long.
The researchers named it Willo after the wife of the rancher on whose
property it was found.
Thescelosaurus means "marvelous lizard" and the researchers believe it was
a member of the T. neglectus species.
"Thescelosaurus neglectus, the marvelous neglected lizard," Russell said.
"Marvelous? Yes. But I don't think this one is going to be neglected any
more."
More information is available at http://www.dinoheart.org.
E-mail this story
[...]
Copyright (c) 2000 Reuters Limited. All rights reserved.
Republication or redistribution of Reuters content is expressly prohibited
without the prior written consent of Reuters.
Reuters shall not be liable for any errors or delays in the content, or for any
actions taken in reliance thereon.
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"Popper himself, in "The Poverty of Historicism" singles out
evolutionary theory for an attack. "Can there be a law of evolution?" "No,
the search for the law of the 'unvarying order' in evolution cannot possibly
fall within the scope of scientific method...". By this, Popper means only
that the history of living organisms and their transformations on Earth are a
specific sequence of unique events, no different from, say, the history of
England. Since it is a unique sequence, no generalities can be constructed
about it." (Lewontin R.C., "Testing the Theory of Natural Selection,"
review of Creed R., ed., "Ecological Genetics and Evolution," Blackwell:
Oxford, 1971, in Nature, Vol. 236, March 24, 1972, p.181. Ellipses in
original.)
Stephen E. Jones | sejones@iinet.net.au | http://www.iinet.net.au/~sejones
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