Dr Mary Schweitzer of the North Carolina Museum of Natural Sciences and PARC, discovered in 2005 what seemed to be soft tissue in a 67 million year old Tyrannosaurus rex. Then she saw similar preservation in an even older (~80 million year old) Brachylophosaurus canadensis. Schweitzer and colleagues used chemical and molecular analyses in 2007, and again in 2009, to confirm that the fibrous material collected from the specimens was collagen.

Next, using techniques including microscopy, histochemistry and mass spectrometry, Schweitzer demonstrated that the star shaped cellular structures within the fibrous matrix were osteocytes, or bone cells, cellular structures which react to specific antibodies, including one—a protein known as PHEX—found in the osteocytes of living birds. Schweitzer explained:

The PHEX finding is important because it helps to rule out sample contamination. 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. 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.

Schweitzer and her team also tested for the presence of DNA within the cellular structures, using an antibody that only binds to DNA. The antibody reacted to small amounts of material within the “cells” of both the T rex and the B canadensis.

To rule out the presence of microbes, they used an antibody that binds histone proteins, which bind tightly to the DNA of everything except microbes, and got another positive result. They then ran two other histochemical stains which fluoresce when they attach to DNA molecules. Those tests were also positive. These data strongly suggest that the DNA is original, but without sequence data, it is impossible to confirm that the DNA is dinosaurian. Schweitzer concludes:

The data thus far seem to support the theory that these structures can be preserved over time. Hopefully these findings will give us greater insight into the processes of evolutionary change.

Originally posted 2012-10-30 22:59:15. Republished by Blog Post Promoter

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