A LOT HAS happened in the past 165m years. Dinosaurs populated Earth and then died off. The ancestors of whales gave up the land and went back into the oceans. The ancestors of humans gave up the trees and came down to the plains. And all the while, a species of bacterium which lives deep underground and feeds on chemicals extracted from rocks continued merrily along without any apparent change at all. The term "living fossil" is much bandied about to describe modern creatures that look like relicts of the past. In this case, though, it really does seem an appropriate description. Not only is Desulforudis audaxviator found, like real fossils, inside rocks, it also seems to have remained unchanged since the Jurassic.
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