MESSAGE
| DATE | 2005-03-25 |
| FROM | From: "Ruben I Safir - Secretary NYLXS"
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| SUBJECT | Subject: [hangout] Mind Boggling News from the Scientific Front
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Dinosaur Find Takes Scientists Beyond Bones
By JOHN NOBLE WILFORD
Published: March 25, 2005
Alive as dinosaurs may seem to children, knowledge of them as living creatures
is limited almost entirely to what can be learned from bones that have long
since turned to stony fossils. Their soft tissues, when rarely recovered, have
lost their original revealing form.
But now a 70-million-year-old Tyrannosaurus rex discovered in Montana has
apparently yielded the improbable, scientists reported yesterday: soft
tissues, including blood vessels and possibly cells lining them, that "retain
some of their original flexibility, elasticity and resilience."
Moreover, an examination with a scanning electron microscope showed the
dinosaur's blood vessels to be "virtually indistinguishable" from those
recovered from ostrich bones. The ostrich is today's largest bird, and many
paleontologists think birds are living descendants of some dinosaurs.
In a paper being published today in the journal Science, the discovery team
said the remarkable preservation of the tissue might open up "avenues for
studying dinosaur physiology and perhaps some aspects of their biochemistry."
Speaking at a teleconference, the team leader, Dr. Mary H. Schweitzer of North
Carolina State University, said, "Tissue preservation of this extent, where
you still have this flexibility and transparency, has never been noted in a
dinosaur before."
Dr. Schweitzer, as well as scientists not connected with the research,
cautioned that further analysis of the specimens was required before they
could be sure the tissues had indeed survived largely unaltered. They said the
extraction of DNA for studies of dinosaur genetics and for cloning experiments
was only a long shot, though at least reasonably possible.
In a separate article in Science, Dr. Lawrence M. Witmer, an Ohio University
paleontologist who had no part in the research, said: "If we have tissues that
are not fossilized, then we can potentially extract DNA. It's very exciting."
If the tissues are as well preserved as they seem, the scientists hold out
some hope of recovering intact proteins, which are less fragile and more
abundant than DNA. Proteins might provide clues to the evolutionary
relationship of dinosaurs to other animals and possibly help solve the puzzle
of dinosaur physiology: whether, as argued, dinosaurs were unlike other
reptiles in being warmblooded.
"If we can isolate certain proteins, then perhaps we can address the issue of
the physiology of dinosaurs," said Dr. Schweitzer, a biologist affiliated with
Montana State University as well as North Carolina State.
Excavations of dinosaur remains sometimes turn up preserved tissues other than
bone, including feathers, embryonic fragments and internal organs. But as Dr.
Schweitzer's group noted, while in these cases their shapes may be preserved,
their original composition has not survived "as still soft, pliable tissues."
It is usually difficult to determine what such modified tissues were like in
life when fossils are more than a few million years old. The last of the
dinosaurs died out 65 million years ago.
The T. rex with the soft tissue was found in 2003 by a fossil-hunting team led
by John R. Horner, a paleontologist with the Museum of the Rockies at Montana
State . Mr. Horner is a co-author of the journal report, along with Jennifer
L. Wittmeyer of North Carolina State and Dr. Jan K. Toporski of the Carnegie
Institution of Washington.
The trials of fieldwork led to the discovery of soft tissue inside a thighbone.
Scientists cannot be sure why the tissues survived as they did, though the
protection afforded by the bone was almost certainly one factor. Another may
have been the possibility that the animal was buried in a virtually
oxygen-free environment very soon after death.
Geologically, the T. rex skeleton was excavated from the Hell Creek Formation,
in sandstone laid down about 70 million years ago. Geographically, this was
deep in a remote corner of the Charles M. Russell National Wildlife Refuge, in
Montana. The only way to get the heavy fossils out was by helicopter.
Tyrannosaurs were famously huge predators. This one, estimated to have been 18
years old at death, was not as large as most. Its femur, or thighbone, was
three and a half feet long; some T. rex femurs are at least a foot longer. But
the creature was large enough so that some of the rock-encased long bones had
to be broken in half to fit a helicopter rig - not something paleontologists
like to do.
At a laboratory in Bozeman, scientists inspected the broken thighbone before
anyone had a chance to apply preserving chemicals, which would have
contaminated the specimen. Dr. Schweitzer and colleagues noticed unusual
tissue fragments lining the marrow cavity inside the dense bone. Fossilization
had not been complete.
When fossilizing mineral deposits in the tissues were dissolved by a weak
acid, the scientists were left with stretchy material threaded with what
looked like tiny blood vessels. Further examination revealed reddish-brown
dots that the scientists said looked like the nuclei of cells lining the blood
vessels.
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