5 ms·
one minor snag in that narrative is half-life of DNA which is 521 years. Last dinosaurs (of ye olde) were when?
by Keyframe 4y ago
one minor snag in that narrative is half-life of DNA which is 521 years. Last dinosaurs (of ye olde) were when?
- credit_guy 4y agoJust one year after that paper claiming the DNA half life of 521 years[1], the DNA of horse from 700k years ago was sequenced [2]. That would be about 1344 half-lives. Then, in 2021 the DNA of a mammoth that lived 1.2 million years ago was sequenced. To answer your question, dinosaurs last lived 65 million years ago. [1] https://www.nature.com/articles/nature.2012.11555 https://www.nature.com/articles/nature.2012.11555 [2] https://www.nationalgeographic.com/science/article/130626-ancient-dna-oldest-sequenced-horse-paleontology-science https://www.nationalgeographic.com/science/article/130626-an... [3] https://www.science.org/content/article/mammoth-molars-yield-oldest-dna-ever-sequenced https://www.science.org/content/article/mammoth-molars-yield...
- nemo 4y agoDinosaurs (non-avian) lived 66 million years ago+. The conditions that can preserve DNA longer is cold which is why Mammoth DNA in permafrost was able to be recovered. There's no permafrost from 66 million years ago. There's no means by which pre-avian dinosaur DNA might be preserved.
- erulabs 4y agoWhat about the Michael Crichton "mosquito stuck in amber" idea? I've been curious about that for ages - assuming the amber is room temperature, would that even help preserve DNA for an extra day? I've been leaning towards "no", but I am extremely far from an organic chemist!
- titaniumtown 4y agoJust because it's encased in something it doesn't prevent the decay of the actual DNA afaik.
- kadoban 4y agoEncasing in amber really only shields you from outside things. Those include chemicals (especially oxygen, oxygen is _very_ reactive), life (bacteria) and possibly some shielding against radiation (eg light). Those do encompass a _lot_ of the reason that anything decays, but unfortunately it's not _all_ of the reasons things decay. And over millions of years, the remaining decay mechanisms are enough that you're really not going to have much/any intact DNA. It makes for a good story though.
- erulabs 4y agoCool, this was my uneducated assumption, thanks!
- credit_guy 4y agoHow about this mummified dinosaur from 110 million years ago? https://www.cnn.com/2020/06/02/world/nodosaur-fossil-stomach-contents-scn-trnd/index.html https://www.cnn.com/2020/06/02/world/nodosaur-fossil-stomach...
- _yb2s 4y agoGP wasn't saying they will find dinosaur DNA, they were saying it may be possible to statistically infer a dinosaur sequence from the sequences of many remaining descendant species, that are still alive today.
- Keyframe 4y agoSounds like Crichton device as well.