Paleontology

Paleontology is the scientific study of the animals, plants, and other organisms that lived in prehistoric times. It largely involves the study of fossil remains. The fossil record enables paleontologists to reconstruct what type of life existed at various periods in Earth's long history.

Paleontology has often been described simply as the scientific study of fossils. Fossils are the remains of once-living plants or animals that were preserved in rock or other material. Fossils are found in sedimentary rock, or rock that started out as wet sand or mud. Fossilization occurs if an animal or plant dies and is quickly covered with a sediment like mud. Although its soft body parts usually decay, the harder parts (like teeth and bone) are sometimes preserved by petrifaction. This means that its organic material is replaced over millions of years by minerals that turn it into rock. By studying this evidence of the ancient past, paleontologists can reconstruct an account of what kind of life existed in various periods of Earth's history. This, in turn, allows them to go further and try to establish a record of how all the animals and plants that make up today's biosphere (part of Earth that contains life) evolved from their earliest beginnings. In this way, paleontology has often been able to provide actual evidence to support the theory of evolution (the process by which living things change over generations). Paleontology also has its practical aspects and sometimes helps in locating deposits of oil and natural gas. This is not surprising since these "fossil fuels" are often found in the same location as the fossils themselves.

Paleontology combines the skills of geology with that of biology. Geology is essential, since a paleontologist would be lost if he or she had no knowledge of the type of rock where fossils are typically found. The paleontologist also needs to be able to know the ages of different rocks (which indicate the age of the fossils found in those rocks). Biology helps paleontologists figure out how the ancient plants and animals that they discover may have actually lived. Although the word "paleontology" does not have an especially scientific meaning—literally, it means "a discourse on ancient beings"—in practice it has been able to scientifically establish the evolutionary development of life. Paleontology tells us when minor or major extinctions occurred, and sometimes why they happened. Paleontology helps recreate these ancient environments and explains why the plants and animals that lived then were built the way they were.

Like geology (the study of the history of Earth), paleontology is a fairly young science. Before it was established, geologists had no way of determining the relative ages of rocks. By comparing fossils of organisms that lived for a short time, geologists were able to put together a chronology or time line of Earth's history. Serious paleontological research dates back to the early 1800s, and is based on the work of two men born the same year. In England, the geologist William Smith (1769–1839) established the principle of stratigraphy—that the deeper layers of the earth were deposited earlier and were thus older than the layers closer to the surface. This would hold true for the fossils contained in those layers. Based on his theory, Smith was able to arrange fossils in terms of their age. The French anatomist, Georges Cuvier (1769–1832), was so skilled in animal anatomy (their body structure), that he was able to reconstruct a complete animal from an incomplete collection of bones. It was Cuvier who brought the new science of classification (the scientific way of identifying and grouping living things) to fossils. By grouping animals according to their skeletons or internal structure, instead of their outer form or how they looked, Cuvier eventually laid the basis for evolution despite his disagreement with that theory. Modern scientists were eventually able to show that the oldest fossils were in fact ones that differed from the more recent fossils and even more so from living animals.

Modern paleontology uses several advanced dating techniques and has become, like many other branches in the life sciences, more specialized. The study of fossil plants is called paleobotany; that of fossil communities is paleoecology; that of extremely small fossils is micropaleontology; and that branch concerned with the study of fossil spores and pollen is called palynology. Altogether, these branches of paleontology seek to learn the history of life on Earth.

[See alsoDinosaurs; Fossil; Geologic Record; Radioactive Dating ]