The conclusion section of Bailleul et al. (2020) Evidence of proteins, chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage is:
The identification of chemical markers of DNA in Hypacrosaurus suggest it may preserve much longer than originally proposed [30,31]. Even though it is clear that contamination does exist in fossil material and complicates identifications of original organic molecules, it can be accounted for with proper controls. Contamination is not a plausible explanation in this case, and to this date, the possible preservation of original proteins and DNA in deep time has not been convincingly eliminated with data. Although extensive research and sequencing is required to further understand DNA preservation in Mesozoic material, along with its chemical and molecular alterations, our data suggest the preserved nuclear material in Hypacrosaurus was in a condensed state at the time of the death of the organism, which may have contributed to its stability. We propose that DNA condensation may be a favorable process to its fossilization. Additionally, as was suggested for protein fossilization [20,45,46], crosslinking may be another mechanism involved in the preservation of DNA in deep time.
The last three sentences highlight that "the preservation of DNA in deep time" may be aided by both DNA condensation and crosslinking.
If I had to bet I'd say dinosaurs had chromatin but I could not defend it. If one of the conclusions of this paper was that the DNA was in a condensed state, then it sounds like they are not taking it for granted either.
Is this paper the full extent of what's known about DNA condensation in dinosaurs?
Together with condensation, crosslinking is mentioned in the conclusion, but a text search for "crossl" finds no other instances. As it seems closely related to condensation but there's no further information I don't see how to break that out as a separate question yet.
Question: How much is known about dinosaur DNA condensation and crosslinking?
Potentially related and/or helpful:
- Zheng et al. (2021) Nuclear preservation in the cartilage of the Jehol dinosaur Caudipteryx
- Wikipedia: Hypacrosaurus; cells
- Was 14,000+ year old DNA "laying around in cave dirt" protected from degradation, or is it just naturally this robust?
- Roughly speaking how stable are short sections of single-stranded RNA in exposed environments compared to double-stranded DNA?