Blunderov
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"We think in generalities, we live in details"
  
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T. rex, chickens are kin, study shows
« on: 2007-04-14 02:59:32 » |
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[Blunderov] I used to tease my girls when they were little about having 'another slice of dinosaur" or "scrambled dinosaurs on toast".
This fossil was apparently preserved in air-free circumstances very soon after death and became deeply submerged; +- 60 metres. This combination of circumstance prevented the fossil from becoming fully mineralised thus leaving some soft tissue behind. There is the hope that more such fossils might be discovered in the future.
How the mighty are fallen. For now. I hear there is a lost valley in the Amazon where chickens are said to be mighty large...
http://www.thestar.com/article/202722
T. rex, chickens are kin, study shows
REUTERS
Genetic material from a 68 million-year-old Tyrannosaurus rex, is closest to the collagen from chicken bones.
Protein from dinosaur thigh bone gives first genetic evidence of link to birds
Apr 13, 2007 04:30 AM
Julie Steenhuysen
Reuters News Agency
CHICAGO–Tiny bits of protein extracted from a 68-million-year-old dinosaur bone have given scientists the first genetic proof that the mighty Tyrannosaurus rex is a distant cousin to the modern chicken.
"It's the first molecular evidence of this link between birds and dinosaurs," said John Asara, a Harvard Medical School researcher, whose results were published in today's edition of the journal Science.
Scientists have long suspected that birds evolved from dinosaurs based on a study of dinosaur bones, but until recently, no soft tissue had survived to confirm the link.
That all changed in 2005 when Mary Higby Schweitzer of North Carolina State University reported finding soft tissue, including blood vessels and cells, in a T. rex bone dug out of sandstone from the fossil-rich Hell Creek Formation in Montana.
Schweitzer, in another study appearing in this week's issue of Science, found that extracts of T. rex bone reacted with antibodies to chicken collagen, further suggesting the presence of birdlike protein in dinosaur bones.
For his study, Asara used a highly sensitive technology called mass spectrometry to determine the chemical makeup of bone fragments provided by Schweitzer and her team.
He first had to purify the bone extract, which came in the form of a gritty brown powder that remained after minerals were extracted. Asara then broke it down into peptide fragments, little bits of proteins, isolated into the amino acid sequences that make them up.
"It was very tough to get anything," he said in a phone interview.
He wound up with seven separate strands of amino acid, five of which were a particular class of collagen, a fibrous protein found in bone.
Next, Asara had to interpret the sequences. He compared his results to collagen data from living animals. Most matched collagen from chickens, while others matched a newt and frog.
"Based on all of the genomic information we have available today, it appears these sequences are closer to birds or chickens than anything else," Asara said.
Ultimately, scientists had hoped to find genetic material that was unique to the T. rex. That was not possible with the tiny T. rex sample.
Asara said the T. rex protein sequence was useful in giving clues about the evolution of the species, while the researchers said the results may change the way that people think about fossil preservation.
"The fact that we are getting proteins is very exciting," said paleontologist Jack Horner, who dug up the T. rex in 2003 and is the paper's co-author.
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