The study of fossils provides three main types of information:
1. the best method yet devised for recognising Phanerozoic time divisions over wide areas;
2. one of the best methods for distinguishing past sedimentary environments;
3. the only direct evidence of evolution through time, and thus a demonstration of the evolutionary relationships between those groups of animals and plants which have developed since the early Cambrian.
Palaeontology thus serves both Geology and Biology. This multiple service is even more evident today than in the past, especially in such fields as marine ecology. Not only are many modern ecological techniques being applied to fossil collecting, but the necessity to find out more about past environments has resulted in many palaeontologists wading and dredging to find out for themselves what is happening in modern seas.
This article is essentially a personal view of a palaeontologist who is attempting to use fossils to unravel past events and conditions in the light of present day processes. Of necessity, it cannot be a review of more than a small part of palaeontology. Most of the examples selected to illustrate this article are taken from fossil groups about which I have some experience; many of the points could equally well be made from other fossil groups. Drs. H. G. Reading and B. W. Sellwood have kindly made some comments on the typescript.
Fossils as time indicators
Some fossils can be used as a rough working basis for stratigraphy without considering them as much more than formed