Fossil DNA hunting is a recent phenomenon, as it was long assumed that the molecules could not survive the vagaries of time and preservation to become fossils.
The current claim for oldest preserved DNA comes from 419-million-year-old salt deposits from Canada. This is an amazing claim, as previous “oldest DNA” reports are from animals only tens of thousand years old.
Every claim of old DNA is subject to intense scrutiny and is accepted only after successful independent trials to replicate the results. The 419 million year old DNA is from salt-loving or halophilic bacteria, representatives of which are still around today and which provide a comparison for the fossil DNA sequences.
The discovery of halophiles gives encouragement to looking for microbes in other unusual places...like Mars. Click on today's title to learn more.
Reference: J.S. Park, et al.,, 2009, Geobiology 7 no. 5, p. 515-523, Haloarchaeal diversity in 23, 121 and 419 MYA salts
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