IT ISN’T EASY to become a fossil. The fate of nearly all living organisms—over 99.9percent of them—is to compost down to nothingness. When your spark is gone, everymolecule you own will be nibbled off you or sluiced away to be put to use in some othersystem. That’s just the way it is. Even if you make it into the small pool of organisms, the lessthan 0.1 percent, that don’t get devoured, the chances of being fossilized are very small.
In order to become a fossil, several things must happen. First, you must die in the rightplace. Only about 15 percent of rocks can preserve fossils, so it’s no good keeling over on afuture site of granite. In practical terms the deceased must become buried in sediment, whereit can leave an impression, like a leaf in wet mud, or decompose without exposure to oxygen,permitting the molecules in its bones and hard parts (and very occasionally softer parts) to bereplaced by dissolved minerals, creating a petrified copy of the original. Then as thesediments in which the fossil lies are carelessly pressed and folded and pushed about byEarth’s processes, the fossil must somehow maintain an identifiable shape. Finally, but aboveall, after tens of millions or perhaps hundreds of millions of years hidden away, it must befound and recognized as something worth keeping.
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