8 ms·
Hey, I'm the journalist who wrote the story. A few things: - The organic-rich film preserving the outlines of scales (so, yes, fossilized skin) is only a few mi
by michaelgreshko 9y ago
Hey, I'm the journalist who wrote the story. A few things:
- The organic-rich film preserving the outlines of scales (so, yes, fossilized skin) is only a few millimeters thick. So Mitchell had to prepare the fossil extremely slowly in order to follow the film through the matrix.
- The half-life of DNA is ~521 years at 13.1°C, as found in this 2012 paper: http://rspb.royalsocietypublishing.org/content/279/1748/4724 http://rspb.royalsocietypublishing.org/content/279/1748/4724
The team's model predicts higher half-lifes at truly freezing temperatures, but even at the extreme end, there's no way DNA would survive 110 million years.
- The dating on the site is well constrained to ~110 million years old. The fossil was found in the Wabiskaw Member of the Clearwater Formation, a well-dated rock formation in Alberta. The underlying oil sands have been radiometrically dated to 112±5.3 million years old. (http://science.sciencemag.org/content/308/5726/1293 http://science.sciencemag.org/content/308/5726/1293)
- ChuckMcM 9y agoReally awesome writeup of the find. Is Suncor going to be doing any additional, and somewhat more reserved, excavating to understand whether or not there are other important fossils nearby?
- michaelgreshko 9y agoThanks. Interestingly, this is the first large fossil like this that Suncor had run across, in all the digging they had done up in the oil sands. And as you can imagine, finding a land animal like this nodosaur in the middle of what would've been a shallow sea is extraordinarily unlikely. Other mining companies have found other fossils in similar formations, though usually of non-dinosaur marine reptiles (e.g. http://www.sciencemag.org/news/2016/10/ancient-sea-monster-battle-revealed-unusual-fossil http://www.sciencemag.org/news/2016/10/ancient-sea-monster-b...).
- amelius 9y agoHow much does the DNA degrade (i.e., what does half life mean)? Would it be possible to align any preserved short sequences back together?
- zbyte64 9y agoIf the DNA strands keep getting chopped in half then eventually the strands will be too short to extract anything useful.
- michaelgreshko 9y agoWhat zbyte64 said. Once the animal dies, the enzymes that constantly fix and error-check DNA are no longer around. DNA then degrades over time, cleaving in half every ~521 years on average. So past a million years or two, the fragments are so small, meaningfully putting them back together would be an impossible task, like reconstructing a porcelain bowl you had ground into dust.
- amelius 9y agoYes, but it is a statistical process. There are many copies of the DNA, so some fragments might still be useful (?)
- erik-g 9y agoSo, if we assume that the dinosaur has 1 billion base pairs in its genome (huge assumption, see my other comment), it has degraded over 110 million years with a half life of 512 years, there is functionally 0 base pairs left[1] in each dna helix. Even statics can't help much there! I'm wide open to the possibility that I am incredibly wrong in any one of these assumptions however [1] - http://www.calculator.net/half-life-calculator.html?type=1&nt=&n0=1000000000&t=110000000&t12=512&x=63&y=15 http://www.calculator.net/half-life-calculator.html?type=1&n...
- Aron 9y agoI didn't actually look into this or any of the references but I suspect the half-life model is not appropriate in the extreme case. That is, it's an approximation that works on a certain non pathological scale like newtonian physics. Probably need the quantum mechanics version for this.