Dinosaur secrets are a tissue of thighs

[Strengthandhonour]

IN A retrieval once thought unattainable, scientists have recovered and identified proteins in a bone from a well-preserved Tyrannosaurus rex that was fossilised 68 million years ago.
The scientists say the success opens the door for the first time to the exploration of molecular-level relationships between ancient extinct animals, instead of relying only on their skeletal remains.
Dinosaur-fossil hunters are planning nine expeditions this year to search wide and deep for more specimens for similar tests. A few large dinosaur bones already in laboratories may be examined for surviving traces of organic matter.
The earliest previously identified ancient proteins were from mammoths that died about 300,000 years ago. The oldest confirmed samples of DNA have come from Neanderthals that lived 30,000 to 50,000 years ago.
The extraction of DNA would be necessary for studies in dinosaur genetics and for cloning experiments.
Repeated analysis of the T. rex proteins, the researchers said, had uncovered new evidence of a link between dinosaurs and birds, a widely held but contentious hypothesis. Three of the seven reconstructed protein sequences were closely related to chickens. The scientists resisted being drawn into speculation on the likely taste of a T. rex drumstick.
Two research teams are reporting the findings in the latest issue of the journal Science.
Mary Higby Schweitzer, of North Carolina State University, who leads one of the groups, said it had always been "assumed that preservation does not extend to the cellular level" in ancient fossils. Dr Schweitzer described several tests conducted on soft tissues found deep inside the tyrannosaurus's thighbone, excavated in eastern Montana.
Though barely detectable, proteins of collagen 1, the main organic component of bone, were separated. Fragments of the protein, called peptides, were pieced together into strands of the seven sequences. Three of these reacted with antibodies to chicken collagen. Two others appeared possibly related to two living creatures: a frog and a newt.
The second team, led by John Asara, of the Harvard Medical School and Beth Israel Deaconess Medical Centre in Boston, said its independent examination of the material by mass spectroscopy had confirmed the presence of proteins in the tissue.
Lewis Cantley, a Harvard biology professor on the team, said: "Basically, this is the breakthrough that says it's possible to get sequences beyond 1 million years." This had been thought of as the absolute time barrier for the preservation of organic matter in animal remains.
"We can now start to create relationships between extinct and living organisms," Dr Asara said, adding that the T. rex tests supported the idea "that birds are derived from dinosaurs or are closely related".
The huge tyrannosaurus thighbone was discovered in 2003, excavated at a depth of 20 metres in a dinosaur-rich bed of sedimentary rock underlying much of Montana and Wyoming.
Dr Schweitzer cut into the thick bone and recovered soft tissues including blood vessels and possibly cells which, she said at the time, "retain some of their original flexibility, elasticity and resilience". This had never been found in a dinosaur before.
The size of the bone and the depth of its entombment might have accounted for the unusual preservation of the tissues.
More than 100 fossil hunters will be fanning out this year in the American west and as far away as the Gobi Desert of Mongolia, searching for soft tissue among remains of the largest dinosaurs resting under several metres of rock.
the New York Times




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