Biological Cells Found In Dinosaur Bone Confirmed To Be 67-Million-Year-Old Collagen, Possibly Contain DNA
In 2005, what appeared to be preserved soft tissue was found inside of a 67-million-year-old Tyrannosaurus Rex bone. This soft material was confirmed by later research to be collagen. And now new research has provided further strong evidence that these are in fact dinosaur proteins, and not the result of microbial contamination.
The primary evidence is the soft tissue’s reactivity to antibodies that only target specific proteins found in the bone cells of vertebrates. This rules out microbial contamination. And strongly suggests that there are actual T-Rex cells preserved in the soft tissue, and possibly DNA.
In 2007 after finding soft tissue in the T-Rex bone researchers then found an even older 80-million-year-old Brachylophosaurus canadensis that appeared to also contain soft tissue. As with the T-Rex sample this fibrous material also turned out to be collagen.
After determining that it was collagen, the researchers next step was to find out “if the star-shaped cellular structures within the fibrous matrix were osteocytes, or bone cells.”
By utilizing techniques such as microscopy, mass spectrometry, and histochemistry; the researchers were able to show that “these cellular structures react to specific antibodies, including one — a protein known as PHEX — that is found in the osteocytes of living birds.”
The above photo shows “T.rex (B), B. canadensis (E) and ostrich osteocytes (H) showing positive response to propidium iodide, a DNA intercalating dye.”
“The PHEX finding is important because it helps to rule out sample contamination,” says lead researcher Dr. Mary Schweitzer. “Some of the antibodies that we used will react to proteins found in other vertebrate cells, but none of the antibodies react to microbes, which supports our theory that these structures are surviving osteocytes.”
She continues, “Additionally, the antibody to PHEX will only recognize and bind to one specific site only found in mature bone cells from birds. These antibodies don’t react to other proteins or cells. Because so many other lines of evidence support the dinosaur/bird relationship, finding these proteins helps make the case that these structures are dinosaurian in origin.”
The researchers also did tests to determine if there was any DNA in the cellular structures. Utilizing an antibody that binds only to DNA’s ‘backbone’.
In both the T-Rex sample and the B. canadensis sample the antibody reacted to the minute amounts of material in the ‘cells’. In order to ensure that the positive result wasn’t simply from microbial contamination, the researchers “used an antibody that binds histone proteins, which bind tightly to the DNA of everything except microbes.” Even using this, the result was again positive. To be extra sure, two more tests were done, using histochemical stains that fluoresce when they become attached to DNA molecules. Again the tests were positive.
All of this data when taken together strongly suggests that the DNA is original T-Rex DNA. Until there is sequence data though it’s impossible to confirm.
“The data thus far seems to support the theory that these structures can be preserved over time,” Schweitzer says. “Hopefully these findings will give us greater insight into the processes of evolutionary change.”
The research has just been published online in the journal Bone.
Source: North Carolina State University
Image Credits: Dr. Mary Schweitzer, NC State University; T-Rex via Wikimedia Commons