Quote by David Attenborough

“The chances of any individual animal leaving behind fossilised remains are infinitesimal. First, its dead body has to lie in a place where sediment accumulates. That is most commonly in a lake or sea. Bones lying on the surface of the land are much more likely to be destroyed than preserved. Next, the sediment has to cover the bones before they disappear, preferably even before they are disarticulated. After that, the mud-and the bones within it- has to be compressed and turned into stone by the great, infinitely slow, movements that distort and crumple the earth's crust. That has to happen without the total obliteration of any sign of the bones. And finally, those bones have to be located in the tiny proportion of rocks which happen to be sufficiently close to the surface for them to be discovered by a prospecting palaeontologist. Thus not only have the vast majority of individual animals disappeared without a trace but great numbers of species and families have doubtless existed of which we have no knowledge whatsoever.”

Quote by David Attenborough