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http://www.newscientist.com/article.ns?id=dn7195
http://news.bbc.co.uk/1/hi/sci/tech/4379577.stmBlood vessels recovered from T. rex bone
19:00 24 March 2005
NewScientist.com news service
Jeff Hecht
Palaeontologists have extracted soft, flexible structures that appear to be blood vessels from the bone of a Tyrannosaurus rex that died 68 million years ago. They also have found small red microstructures that resemble red blood cells.
The discovery suggests biological information can be recovered from a wider range of fossil material than realised, which would greatly help the tracing of evolutionary relationships.
The preservation found by the researchers is extraordinary - far better than traditionally expected in dinosaur bone. But that may be because researchers have not been looking hard enough at their finds. Mary Schweitzer at North Carolina State University, US, has also extracted similar soft structures from a few other dinosaur bones.
The leg bone came from a skeleton called B-rex found in a remote canyon in South Dakota, in 2000 by a member of Jack Horner's research team at the Museum of the Rockies in Montana. The 107-centimetre-long femur - small for a T. rex - was intact when found, and its hollow interior had not been filled with minerals. That is unusual for a long-buried bone.
However, with a protective plaster jacket built around it, the bone was too heavy for a helicopter to retrieve it from the remote site and it had to be broken in half. When Horner's group split the bone, they carefully took samples for Schweitzer, then working at the Museum of the Rockies.
"Elasticity and resilience"
Bones are built by cells called osteocytes which are nourished by a rich fabric of blood vessels. The osteocytes secrete proteins which collect the calcium compounds that give bones their strength.
To see what remained of this internal structure, Schweitzer soaked samples of the core of the bone in a solution that dissolved the calcium compounds. This left what she describes as "a flexible vascular tissue that demonstrates great elasticity and resilience".
For comparison, she then examined ostrich bones, as these birds are the largest and closest living relatives of T. rex. She found similar structures when she removed the calcium from the ostrich bones and treated the mixture with enzymes to break down collagen fibre in the bony matrix.
Protein sequencing
Other researchers have previously recovered traces of protein from dinosaur bones, and indeed just two weeks ago Schweitzer reported traces of protein in 70 million year old dinosaur eggs.
"[The T. rex paper] suggests that biological and biochemical information might be recoverable from a wide range of fossil material," says Angela Milner of the Natural History Museum, in London, UK, who has detected proteins in Iguanadon bone. "There certainly seem to be blood vessels," she told New Scientist.
The next step will be to isolate proteins and try to sequence them. Comparing protein sequences could help trace relationships with other prehistoric beasts and with animals alive today. Schweitzer decline to discuss DNA because she does not work with it, but DNA is far less stable than proteins so is usually broken into fragments, even in tissue that has been frozen since the ice age.
Journal reference: Science (vol 307, p 1952)
T. rex fossil has 'soft tissues'
Dinosaur experts have extracted samples of what appear to be soft tissues from a Tyrannosaurus rex fossil bone.
The US researchers tell Science magazine that the organic components resemble cells and fine blood vessels.
In the hotly contested field of dino research, the work will be greeted with acclaim and disbelief in equal measure.
What seems certain is that some fairly remarkable conditions must have existed at the Montana site where the T. rex died, 68 million years ago.
Normally when an animal dies, worms and bugs will quickly eat up anything that is soft.
Then, as the remaining bone material gets buried deeper and deeper in the mud, it gets heated, crushed and replaced by minerals, turning it to stone.
Fine-scale process
The form, and nothing else, is all that is left of the original. On the outside, the hindlimb fossil designated MOR (Museum of the Rockies specimen) 1125 has this appearance.
But when Dr Mary Schweitzer, of North Carolina State University, dissolved away the minerals, she found something extraordinary inside.
She discovered transparent, flexible filaments that resemble blood vessels. There were also traces of what look like red blood cells; and others that look like osteocytes, cells that build and maintain bone.
"This is fossilised bone in the sense that it's from an extinct animal but it doesn't have a lot of the characteristics of what people would call a fossil," she told BBC News.
"It still has places where there are no secondary minerals, and it's not any more dense than modern bone; it's bone more than anything."
Dr Schweitzer is not making any grand claims that these soft traces are the degraded remnants of the original material - only that they give that appearance.
She and other scientists will want to establish if some hitherto unexplained fine-scale process has been at work in MOR 1125, which was pulled from the famous dinosaur rocks of eastern Montana known as the Hell Creek Formation.
Protein route
"This may not be fossilisation as we know it, of large macrostructures, but fossilisation at a molecular level," commented Dr Matthew Collins, who studies ancient bio-molecules at York University, UK.
"My suspicion is this process has led to the reaction of more resistant molecules with the normal proteins and carbohydrates which make up these cellular structures, and replaced them so that we have a very tough, resistant, very lipid-rich material - a polymer that would be very difficult to break down and characterise, but which has preserved the structure."
But if there are fragments, at least, of the original dinosaur molecules, their details could provide new clues to the relationship between T. rex and living species, such as birds.
Inevitably, people will wonder whether the creature's DNA might also be found. But the "life molecule" degrades rapidly over thousand-year timescales, and the chances of a sample surviving from the Cretaceous are not considered seriously.
"I actually don't work with DNA and my lab is not set up to do that," said Dr Schweitzer. "Our goal is more to look to see what we can find with respect to the proteins that are coded by the DNA.
"To a large degree, most of the chemical studies that have been done suggest proteins are more durable than DNA and they have almost the same kind of information because they use DNA as their template."
Dr Collins added: "I would agree that proteins are the molecules to go for - they are the major macromolecules in bone.
"We've got some very interesting research coming out from a number of labs looking at stable isotopes (different forms of the same atom) in bones and clearly information about diets which comes from such isotopes may now be amenable from these dinosaur materials."
However, he cautioned that the great age of MOR 1125 may put such detail beyond the investigating scientists.
