Oldest Dinosaur Protein Found -- Blood Vessels, More
for National Geographic News
|May 1, 2009|
The fossilized leg of an 80-million-year-old duck-billed dinosaur has yielded the oldest known proteins preserved in soft tissue—including blood vessels and other connective tissue as well as perhaps blood cell proteins—a new study says.
The research was led by the team behind the controversial 2007 discovery of protein from similar soft tissues in 68-million-year-old Tyrannosaurus rex bones.
"It was not a one-hit wonder," said John Asara of Harvard Medical School, who led the protein-sequence analysis.
(See a prehistoric time line)
The proteins were recovered from a hadrosaur femur that had been encased in sandstone, which appears to prevent complete tissue degradation, Asara said.
Preliminary microscopic analysis revealed structures resembling blood vessels, cells, and collagen, he noted.
Those initial speculations were confirmed by applying antibodies to the tissue that are known to react with proteins. The tests suggested the presence of collagen and other proteins, including hemoglobin, the protein in red blood cells.
Dinosaur Blood Cells?
The hints of hemoglobin remain speculative and are not covered in the new, peer-reviewed study, which appears in today's issue of the journal Science.
Some scientists suspect the hemoglobin is a contaminant.
If it's not a contaminant, "it is much bigger news than [the confirmed discoveries of blood vessels and other connective tissues in] this paper," said Pavel Pevzner, a computational biologist at the University of California, San Diego, who was not involved in the new research.
A confirmed dinosaur-hemoglobin discovery would open the door to the recovery of many dinosaur proteins, including DNA proteins, he noted—raising the specter of Jurassic Park-style "resurrections."
Study co-author Asara said that, so far, there's not much his team can say about the hemoglobin, which is difficult to identify with current technology.
"Although, we don't believe that it is contamination."
Fleshing Out the Family Tree
Asara analyzed the tissue samples with a mass spectrometer, which reveals chemical makeup by telling scientists the masses of different elements in a sample.
He uncovered eight collagen proteins, and a colleague compared them with samples from living animals as well as mastodon and T. rex fossils.
The results placed the duck-billed dinosaur, Brachylophosaurus canadensis, on the same family-tree branch as T. rex. And, as expected, both the duckbill and T. rex were more closely related to chickens and ostriches than to alligators and lizards.
The new study may dispel some of the controversy over the team's 2007 T. rex soft-tissue study—for example, critics argued that the tissue was actually introduced to the specimen through mishandling.
(See "Dinosaur Slime Sparks Debate Over Soft Tissue Finds.")
UC San Diego's Pevzner—who had been critical of the technique used to analyze the T. rex proteins—said the new study was "done the right way," with more stringent controls to guard against contamination and a higher bar for defining the material as dinosaur protein.
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