Far older than anyone has ever found or expected, the protein came in the form of collagen from the back thigh bone of the oldest T. rex on record. Collagen is the main organic compound found in bone. Its presence is expected to help scientists better understand the relationship between extinct and living organisms.
Montana State University researchers and others who analyzed the collagen said the discovery is significant for several reasons. It strengthens their belief that dinosaurs and birds are related. The instrument and techniques they used offer researchers a better way to study fossil preservation and evolution in the future. Since they pushed the limits of technology in this project, it opens the door for more discoveries and may have implications for the medical field.
"The fact that we are getting protein is very, very exciting," said Jack Horner, one of several co-authors on a paper published in the journal Science and released today, April 12. Horner is curator of paleontology at MSU's Museum of the Rockies.
Mary Higby Schweitzer of North Carolina State University and formerly from MSU authored the paper, titled "Analyses of soft tissue from Tyrannosaurus rex suggest the presence of protein." Five MSU researchers were among the co-authors. Besides Horner, they were Zhiyong Suo, Recep Avci and Fernando Teran Arce from the Imaging and Chemical Analysis Laboratory in the physics department, and Mark Allen from the chemistry and biochemistry department.
Schweitzer's paper was released in conjunction with another paper that involved Schweitzer and mass spectrometry to study a half-million-year-old mastodon.
The Eastern Montana dinosaur was discovered in 2000 between Jordan and the Fort Peck Reservoir by Bob Harmon, chief preparator of paleontology at the Museum of the Rockies. The dinosaur is called B. rex in honor of Harmon who was on his lunch break when he looked up and saw a dinosaur's foot bone sticking out of a cliff. After the dinosaur was excavated, part of its femur went to Schweitzer. She and her team of researchers looked inside and ran a variety of tests that revealed preserved soft tissues and blood vessels in the bone. They also found medullary tissue which is only found in female birds during the egg-laying cycle and proved that B. rex was actually a female.
Science published papers about both discoveries in 2005.This week's paper announced that B. rex's leg contained low levels of collagen. Schweitzer, who was able to run seven protein sequences from the collagen, said scientists thought previously that collagen couldn't survive even one million years. John Asara, one of the paper's co-authors, said the oldest protein previously found was 300,000 years old. Asara works at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston.
Schweitzer noted that protein is related to DNA, but different. Comparing them to first cousins, she said DNA is a gene, and it codes proteins.
Schweitzer and other researchers said during an April 11 teleconference that seven sequences of protein isn't a lot, but they are valuable. The scientists added that three of the sequences were more like those found in a chicken than any other organism, which reinforced the belief that dinosaurs and birds are related.One protein sequence matched that of a newt. Another matched a frog's.
Horner said paleontologists have long wanted to find fossils that are genuinely well-preserved, and scientists had learned an important lesson from B. rex.
"The way to get specimens like this is to spend a lot of time getting as deep into sediments as we can and into places where there's very little atmosphere or water contamination," Horner explained.
Horner said he plans to send crews to Mongolia and Montana this summer to look for other fossils that are "exquisitely well-preserved." He noted that the protein found in B. rex was doubly protected. Not only was it hidden inside a dense, large femur bone, but the bone was 60 feet below the top of the outcrop and under 1,000 cubic yards of rock. That protection kept the fossils from being contaminated by bacteria, the atmosphere or modern ground water.
Schweitzer and her co-authors used a variety of techniques and instruments to analyze the chemical and molecular makeup of the B. rex tissues. For that reason, she said most curators of paleontology don't like her. They want dinosaur bones to remain intact, but hers is a "destructive analysis." It requires, among other things, the removal of minerals, bone slicing and tissue dehydration.
Schweitzer praised Horner for caring more about learning new lessons than keeping bones in one piece. As technology improves, she said it will open the door to a host of other investigations.
Science is a weekly journal that publishes scientific news, as well as the most significant breakthroughs in global research. It is the world's largest circulation journal for a general science audience.
Evelyn Boswell, (406) 994-5135 or firstname.lastname@example.org