"We are lucky to have fossils at all. It is a remarkably 
fortunate fact of geology that bones, shells and other hard 
parts of animals, before they decay, can occasionally leave an 
imprint which later acts as a mould, which shapes hardening 
rock into a permanent memory of the animal. We don't know what 
proportion of animals are fossilized after their death--I 
personally would consider it an honour to be fossilized--but it 
is certainly very small indeed. Nevertheless, however small the 
proportion fossilized, there are certain things about the 
fossil record that any evolutionist should expect to be true. 
We should be very sruprised, for example, to find fossil humans 
appearing in the record before mammals are supposed to have 
evolved! If a single, well-verified mammal skull were to turn 
up in 500 million year-old- rocks, our whole modern theory of 
evolution would be utterly destroyed. Incidentally, this is a 
sufficient answer to the canard, put about by creationists and 
their journalistic fellow travellers, that the whole theory of 
evolution is 'unfalsifiable' tautology. Ironically, it is also 
the reason why creationsist are so keen on the fake human 
footprints, which were carved durning the depression to fool 
tourists, in the dinosaur beds of Texas."

    -Richard Dawkins, _The Blind Watchmaker_