WHEN I am dead, the chance that my bones will become fossilized is very remote. Bones decay away like the rest of our bodies unless a lot ofvery unlikely things happen. First of all, a dead body will not leave any permanent remains in the form of a fossil unless it happens to be covered up and thus protected from decay. That is fairly easy in the case of animals in the ·sea. Rivers are always carrying sediment out and depositing it, and tides and currents shift the sediment and cover up the bodies of dead animals. But even in this case it is by no means likely that the bones will be fossilized. Much more probably they will gradually dissolve away and leave no trace of themselves. Fossilization is rather a complicated process. It involves the replacement of each particle of bone, as it dissolves away, by a less soluble and therefore more permanent substance. When that has happened, the chances are still very remote that anyone will find the fossil thousands or millions of years later. Our quarries and mines and cuttings are mere scratches on the surface of the earth. With terrestrial animals the chances of fossilization are still less than with marine ones. They are likely to die and decay without being covered up. It would be quite absurd to look with any great hopefulness for the fossil remains of the ancestors of any given animal. It would not simply

be like looking for the proverbial pin in a haystack, for then you are supposed to have the advantage of knowing that the pin is there. But in this case you are looking for a soluble pin in a haystack in a thunderstorm, and you always have at the back of your mind the disconcerting thought that perhaps it is no longer there.