Eventually the accumulated changes may become so great that the descendant bears little likeness to its remote ancestor and may belong to a different species. On the other hand, evolution links with fossil. How? Fossil is an evident of species that is seen in the past. Thus, it is a trace, or imprint, preserved by natural means, of a plant or animal of past geologic time. The earliest fossils are estimated to be more than 3,000,000,000 years old. Fossils more than 500,000,000 years old are relatively few in number.
There are many forms of fossils. Occasionally an entire animal or its skeleton will be found preserved. More often, however, animal fossils are in the form of a single bone, tooth, or shell. Plant or animal fossils often occur as impressions in coal or rock. The impression may be a complete plant or animal, or a part (such as foot or a leaf). Petrified objects and burrows made by animals are other forms of fossils. On one hand, direct evidence of evolution is obtained when animal or plant breeders raise new varieties b cross-breeding.
Further evidence is provided by laboratory experiments with bacteria and other primitive forms of life. Since these organisms produce new generations within minutes or hours, scientists can observe evolutionary changes that would take thousands of years in more complex forms (Futuyma 2004). Another type of direct evidence comes from paleontology, the study of fossils, in which scientists trace the history of plants and animals. The findings of the paleontologists are important to all the earth sciences.
Fossils show the order in which plants and animals appeared on earth. Fossils provide information about forms of life, such as ancient seaweeds and dinosaurs, which have been extinct for millions of years. They give clues regarding climatic conditions that existed in various ages of the earths history ( Case 2003). Index fossils”fossils of plants or animals known to have lived during a certain period of geologic time”are useful in identifying and dating rock strata (layers).
Furthermore, there is also a great deal of indirect evidence of evolution. For example, before birth all animals with backbones”including man”pass through a stage of development in which they have gill clefts. This fact suggests that these animals are descended from organisms that once lived in water. Another example is the fact that all plants and animals are similar in certain essential ways (Case 2003). All living cells, whether in a germ or an elephant, in a tree or a man, undergo similar process of metabolism, growth, and reproduction.
As a conclusion, evolution and fossil records go hand in hand to trace the existed species in the past. Fossils also have industrial importance. Coal is largely made of the bodies of decayed plant forms, and chalk is formed from the shells of tiny aquatic animals.
Reference: Futuyma, Douglas (2004). Science on Trial: the Case for Evolution (Pantheon Books) Stein, Sara (2006). The Evolution Book: the Story of 4000 Million Years of Life on Earth (Workman) Case, G. (2003). A Pictorial Guide to Fossils (Van Nostrand Reinhold)