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> DNA half life is around 500 years. After a million years, it would have degraded so bad you literally have nothing left to reconstruct no matter how much sample you discover.

That article with the 521 half life of DNA was complete bull. In 2022 they found DNA from a 2 million year old mastodon [1].

The whole 521 year half life is something like "it was that in our sample, and we can't guarantee that the result generalizes". Good maybe for a high school science project, not good for a paper in Nature.

[1] https://www.nature.com/articles/d41586-022-04376-y

The half-life of 521 years does allow for some million year old DNAs to be found. The original paper even noted this possibility in exceptionally good environments [1, section 4]:

> Our results indicate that short fragments of DNA could be present for a very long time; at –5°C, the model predicts a half-life of 158 000 years for a 30 bp mtDNA fragment in bone. Even rough estimates such as this imply that sequenceable bone DNA fragments may still be present more than 1 Myr after deposition in deep frozen environments. It therefore seems reasonable to suggest that future research may identify authentic DNA that is significantly older than the current record of approximately 450–800 kyr from Greenlandic ice cores.

[1] https://royalsocietypublishing.org/doi/10.1098/rspb.2012.174...

Anyone knows what research came out after scientists recovered 70 million-year-old T. rex soft tissue back in 2005 ? I remembered being blown away by the fact we could have soft tissues instead of fossilized remains... https://www.nbcnews.com/id/wbna7285683

https://en.wikipedia.org/wiki/Mary_Higby_Schweitzer

Thanks! So not only preservation of soft tissue was confirmed, although the exact mechanism is not fully understood. But also there are "multiple lines of evidence for material consistent with DNA in dinosaur" found in fossils https://www.sciencedirect.com/science/article/abs/pii/S87563...

> multiple lines of evidence for material consistent with DNA in dinosaur

After reading a paper I don’t think I’ve ever had a thought like this before: did they run that past a legal team before publication? That sounds like a lawyer wrote it.

The language surprised me too! I realize the researchers wanted to be extra cautious (enough to pass peer-review) and that's the reason I did a literal quote instead of paraphrasing.

The original research [1, section 4] is slightly more cautious (but otherwise agrees):

> It is tempting to suggest that we can now predict the temporal limits of DNA survival, and finally refute the claims of authentic DNA from Cretaceous and Miocene specimens. This is, however, not straightforward. One needs information on the number of template molecules in living tissues, and estimates of post-mortem DNA decay rates for each tissue type. However, the half-life predictions display the extreme improbability that an authentic 174 bp long mtDNA fragment of an 80–85 Myr old bone could have been amplified.

I looked at the paper partly because I was interested in the possibility that some multi-base strands survive, even though such strands would be very short. The "half-life" here was measured by qPCR, where a relatively large amplicon (a fragment being amplicated via PCR) was used. So this study doesn't preclude a possibility of very short (~100 bp) strands surviving, though this would require most enzymes to be much less effective at breaking such strands.

[1] https://royalsocietypublishing.org/doi/10.1098/rspb.2012.174...

> But still, on the scale of millions of years, it becomes exceedingly improbable that we can find even 1 copy of a dinosaur genome left.

what about imputing genomics from the phenotypically similar present day animals (birds, reptiles, whatever else)?

You'd essentially be designing a dinosaur genome from scratch

OK but if you throw "AI" into that somewhere you'll have funding!

If anyone needs me, I'll be squatting the opendino.ai domain waiting for my payday.

There was this:

https://www.scientificamerican.com/article/possible-dinosaur...

but it's been pretty quiet afterwards.

As expected honestly. They found "chemical signals" that indicate DNA in the fossil. Such thing can be anything, from contaminations to errorneous readings. To sequence that supposed "DNA" is a whole other level of technology. In fact, it would be so complex that unless they are hiding alien tech somewhere, I dare say we can't do it at all with our current level of technology.

If there is anything at all... it would pretty much require rewriting the book on DNA preservation, given what we know about this right now I'd say 'impossible' but if there ever is any solid evidence to the contrary I'll be more than happy to admit that I was wrong.

Researchers explain that the markers cannot be of the microbial origin because they were chosen to only stain DNA in dead cells, and that those markers were highly concentrated at where DNAs would originally have been before the death. So assuming no other obvious mistakes, there may be short (6+ bp) but still readable DNA strands in the fossil.

That's so short though that it isn't really useful. It would be like piecing together a book given syllables.

Yeah, 6 bp would be too short to be useful. But something like 50 bp would be much more useful, and haven't yet been exactly precluded.

Similarities to birds? "Birds" aren't real, they literally are dinosaurs.

And what about fossilized dna remains? Would it not possible to have somekind od crystalized structure if DNA?

Fossilized means turned to stone. Since DNA is not a crystal, I don't think crystalized DNA is in any way a thing. All the organic stuff, including the DNA, has gone and been replaced with stone in the same shape. But only the same macro shape not the same molecular structures.