Is it possible that the DNA and/or proteins from dinosaurs have been preserved over millions of years to the present day? Have any been found? And if it is possible, how would these structures remain intact for so long?
There has been reported dinosaur protein that was able to be sequenced by Jen Schweitzer and her colleagues. While I think her data is convincing enough to lead me to think they may have it, it is not by any means universally accepted and until some other group independently reports a find, the jury is still out.
As to how it would preserve, there are two things one would need. First, it would have to be protected from any organism that would like to eat it. Second, it would have to be protected from water, which will break it down without other proteins protecting it. Amber is a possible candidate, but as yet has not proven to be up to the task of preserving DNA. Other possibilities include the way that Schweizter found hers. They found it dep within a bone that has been permineralized (all the pore spaces filled in by mineral deposition) quickly after burial, so that original material was locked away within a mineral coat from the external environment and protected from being degraded. Between the bone itself and the mineral coating, it MAY be possible to preserve small fragments. Retrieving significant lengths though would be astronomically more difficult for anything as old as a dinosaur.
Amusingly, Mary Schweitzer wrote a paper suggesting that the 'Dino DNA' reported in the early 90s, and used in the Jurassic Park book and movies as the way of bringing dinosaurs back from the dead, was actually contamination from humans handling of dinosaur fossils.
Since then, however, she and her colleagues have provided Ok to fairly solid evidence (depending on the structure or molecule) for the preservation of a number of small structures and molecules in dinosaur and other fossil bone, including haemoglobin, red blood cells, soft tissue blood vessels, osteocytes (bone forming cells), collagen protein etc from animals like T rex, hadrosaurian dinosaurs and mammoths. They have even done phylogenetic analyses using the collagen protein peptides!
They've not yet found any dino DNA however - it's widely considered to be a 'fragile' molecule that breaks easily, even 'just' in water, and the oldest widely accepted ancient DNA is from 300 thousand year old plants, and from a 65 thousand year old bison. The T rex specimen was 68 MILLION years old, nearly one thousand times older than the bison, and most people think the limit for finding DNA is likely around 1 million years.
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