Fossils give us clues to the geography and ecology of the past and how the continents and seas have changed. Certain animals, like corals, brachiopods, and cephalopods have always lived in the sea, so the presence of these types of fossils indicate a marine environment.

The presence of fossil trees or the bones of land animals would suggest a land environment. Other types of plant and animal remains suggest swamps or marsh conditions.

CLIMATIC CLUES
Fossils demonstrate the existence of different climatic conditions in the past. Fossil ferns found in Antarctica and fossil magnolias from Greenland indicate a much warmer climate for these areas at some time.

Corals, found only in shallow warm seas today, have been found within the Arctic Circle, showing the climate to having been tropical at one time. Fossils of musk oxen from Arkansas and reindeer from France indicate a much colder climate than exists in those areas today.

EVOLUTION CLUES
The study of fossil plants and animals has given us much information about the origin and evolution of organisms living today. Fossils provide one of the strongest lines of evidence to support the theory of evolution. The succession of fossils clearly indicates that life has slowly evolved from a few simple ancestors to the many different organisms that inhabit the earth today.

INDEX FOSSILS
Certain fossils of limited time distribution are always found in certain beds or strata of rock. These are called index fossils. Their presence in rocks located many miles apart show that the rocks were formed at the same time. This use of fossils to correlate strata is important in mapping rock formations and in locating valuable mineral deposits.

FOSSIL FUELS
Fossils themselves or rocks located by fossils provide natural resources valued at billions of dollars. Fossil fuels such a coal, oil, and gas are the remains of ancient plants and animals. Diatomaceous earth (earth containing the microscopic fossil remains of plankton) is used for filters, fillers, in polishes, as insulation, and for many other purposes. Quality amber is reserved primarily for jewelry and such items as pipe stems and cigarette holders. Frozen fossils, such as mammoths, are collected by the Inuit, who chop them up and feed them to their dogs.