Scientists have reportedly isolated short fragments of dna from fossilized dinosaur bones hundreds of millions of years old. the technique used to isolate this dna is the polymerase chain reaction, which is capable of amplifying very small amounts of dna a million‑fold. critics have claimed that the dna isolated from dinosaur bones is not purely of ancient origin but instead has been contaminated by dna from present‑day organisms, such as bacteria, mold, or humans. what precautions, analyses, and control experiments could be carried out to ensure that dna recovered from fossils is truly of ancient origin