Konservat-Lagerstätte (exceptional preservation)

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A deposit in which soft tissues are preserved, as opposed to the shells, bones and teeth that make up almost the whole normal fossil record. Exceptional preservation requires an unusual conjunction — rapid burial, an absence of oxygen and of scavengers, and early mineralisation of tissue before decay destroys it — and each of those conditions is rare, so Lagerstätten are scattered thinly and unevenly through time and space. This is the concept that makes the Cambrian explosion legible as a question about evidence rather than only about biology. Between roughly 520 and 505 million years ago several Lagerstätten happen to exist, so a fauna of soft-bodied animals is visible; through most of the surrounding record no such window exists, and the same animals would leave nothing. A reader who has understood Lagerstätten can no longer read a first appearance in the fossil record as a first appearance in the world, and that single correction changes how every date in this Journey should be held.

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