IT ISN』T EASY to bee a fossil. The fate of nearly all living anisms—over 99.9pert of them—is to post 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 anisms, the lessthan 0.1 pert, that don』t get devoured, the ces of being fossilized are very small.
In order to bee a fossil, several things must happen. First, you must die in the rightplace. Only about 15 pert of rocks preserve fossils, so it』s no good keeling over on afuture site of granite. In practical terms the deceased must bee buried in sediment, whereit leave an impression, like a leaf i mud, or depose without exposure to oxygeting the molecules in its bones and hard parts (and very occasionally softer parts) to bereplaced by dissolved minerals, creating a petrified copy of the inal. Then as thesediments in which the fossil lies are carelessly pressed and folded and pushed about byEarth』s processes, the fossil must somehow maintain aifiable shape. Finally, but aboveall, after tens of millions or perhaps hundreds of millions of years hidden away, it must befound and reized as something worth keeping.
Only about one bone in a billion, it is thought, ever bees fossilized. If that is so, itmeans that the plete fossil legacy of all the Ameris alive today—that』s 270 millionpeople with 206 bones each—will only be about fifty bones, one quarter of a pleteskeleton. That』s not to say of course that any of these bones will actually be found. Bearing inmind that they be buried anywhere within an area of slightly over 3.6 million squaremiles, little of which will ever be turned over, much less examined, it would be something ofa miracle if they were. Fossils are in every sense vanishingly rare. Most of what has lived oh has left behind no record at all. It has beeimated that less than one species ihousand has made it into the fossil record. That in itself is a stunningly infinitesimalproportion. However, if you accept the oimate that the Earth has produced 30billion species of creature in its time and Richard Leakey and Roger Lewin』s statement (inThe Sixth Extin ) that there are 250,000 species of creature in the fossil record, thatreduces the proportion to just one in 120,000. Either way, what we possess is the merestsampling of all the life that Earth has spawned.
Moreover, the record we do have is hopelessly skewed. Most land animals, of course, don』tdie in sediments. They drop in the open and are eaten or left to rot or weather down tonothing. The fossil record sequently is almost absurdly biased in favor of marine creatures.
About 95 pert of all the fossils we possess are of animals that once lived under water,mostly in shallow seas.
I mention all this to explain why on a gray day in February I went to the Natural HistoryMuseum in London to meet a cheerful, vaguely rumpled, very likeable paleontologist namedRichard Fortey.
Fortey knows an awful lot about an awful lot. He is the author of a wry, splendid bookcalled Life: An Unauthorised Biography, which covers the whole pageant of animate creation.
But his first love is a type of marine creature called trilobites that oeemed in Ordoviseas but haveed for a long time except in fossilized form. All shared a basic body planof three parts, or lobes—head, tail, thorax—from whies the name. Fortey found hisfirst when he was a boy clamberi