The bones were dug up at a site in France at two different times. Those dug in 1947 had been stored in collections of the natural history museum of Le Mans, while bones uncovered in 2004 were stored according to strict protocols at -4 degrees Fahrenheit (–20°C).
None of the washed, museum-stored rib samples collected in 1947 produced DNA, but all of the recently excavated bones yielded authentic aurochs sequences.
"As much amplifiable DNA was lost during the 57 years when the aurochs bones were stored in a collection as during the previous 3,200 years of burial," the researchers concluded.
According Geigl and colleagues, the study calls for a revision of fossil conservation procedures.
"Our results show very clearly how detrimental standard treatments are to the preservation of DNA in fossil bones," Geigl said.
Most scientists who study ancient DNA know that the sooner DNA is extracted from a fresh fossil, the better the chances something useful is retrieved, said Ross MacPhee of the American Museum of Natural History in New York.
But the French research has revealed that the best practice is not widespread among fossil hunters and museum curators.
"Good conservation practices should not to add to the damage by just shoving bones into museum drawers at ambient temperature and humidity," MacPhee told Discovery News. "I am convinced that the very best practice is to place the fossils in the most inert environment...freezing is the easiest environment to use."
