https://news.ncsu.edu/2020/03/duckbill-dna/
Researchers have found traces of DNA inside a fossilized dinosaur skull. Cartilage cells, chromosomes and DNA preserved in 75-million-year-old baby duck-billed dinosaur, Hypacrosaurus.
Two cartilage cells were still linked together by an intercellular bridge, morphologically consistent with the end of cell division. Internally, dark material resembling a cell nucleus was also visible. One cartilage cell preserved dark elongated structures morphologically consistent with chromosomes
The team found that the organic matrix surrounding the fossilized cartilage cells reacted to antibodies of Collagen II, the dominant protein in cartilage in all vertebrates. This immunological test supports the presence of remnants of original cartilaginous proteins in this dinosaur. Although bone cells have previously been isolated from dinosaur bone, this is the first time that cartilage-producing cells have been isolated from a fossil
The researchers also isolated individual Hypacrosaurus cartilage cells and applied two DNA-stains. These bind specifically to DNA fragments in extant material, and some of the isolated dinosaur cells showed internal, positive binding in the same pattern as seen in modern cells, suggesting some original dinosaur DNA is preserved.
“The possibility that DNA can survive for tens of millions of years is not currently recognized by the scientific community. Rather, based upon kinetic experiments and modelling, it is generally accepted that DNA persists less than 1 million years.”