[adrian_b]

For now the claim is for possible DNA fragments from the cartilage of a dinosaur, with a length of at least 6 nucleotides, but there is no evidence yet that the fragments are long enough to have preserved any useful information. It is likely that fragments with a length of at least a few hundred nucleotides would be needed.

The paper that started this thread was not about the decomposition of the individual nucleotides, which might be preserved even from dinosaurs, but about the speed of the fragmentation of the DNA molecule, which causes a continuous loss of information until the fragments are so short that no useful information remains.

I certainly hope that we will find cases of extremely lucky preservation of long DNA fragments that are more ancient than what was found until today.

Until now, the oldest DNA that was preserved well enough to allow sequencing of significant parts of it had an age of up to a few tens of thousands of years, e.g. from mammoths, woolly rhinoceroses, cave bears, cave lions, Neanderthal humans etc.