Well-preserved fossils are an important source of information about Earth's history.
Across the globe, new fossils are found every day by novice excavators and seasoned paleontologists alike to reveal some of the Earth's secrets once thought lost. While some of the information obtained can serve immediate economic purposes, such as directing a search for oil or other natural minerals, the most valuable information is what these fossils reveal about the past. Encased in the bones, footprints, egg shells and imprints of long-dead sea creatures, land animals and plants is a treasure trove of information about Earth's history.
Age Indicators of Rock Layers
This fossil of coral reveals the stone was once part of an ancient sea bed.
Fossils are the most important tool in determining the age of sedimentary rock sequences in which they are found. While they do not provide an exact year of encasement, fossils give a reliable age of the rocks in which they are found by being compared with similar species in other regions. These correlations are made possible by consulting the fossil record, a detailed catalog of findings spanning the accepted geological time scale. Index fossils are ideal for dating surrounding rocks and are common, well preserved and easily recognizable. Also called zone fossils, the most important include ammonites, trilobites, pollen and graptolites.
Habits and Behaviors
Fossils are the only link to the lives of ancient or extinct creatures, and much information can be obtain from these solitary, fragile objects. What animals ate and how they moved, their social interactions with each other and how they raised their young can all be learned by studying bones and fossil beds. Preserved remains of ancient creatures, such as skeletons, imprints and teeth, paint a picture of what their life was like including whether they traveled in herds or alone, the living conditions they preferred and migration patterns followed by individual species.
Environmental Indicators
Information about this marine creature's entire ecosystem can be learned from this single fossil.
Information as basic as where the rock was deposited to what types of organisms inhabited the ancient ecosystem can be obtained from just a few well-preserved bones or other fossils. By using similar living organisms as a jumping off point, scientists can create an educated picture of what the environment of any dig site in the world used to be like during the lifetime of unearthed plants and aminals. Organisms with living descendants obviously yield the most reliable results, as predictions become less accurate once scientists encounter extinct plants and animals, whose survival requirements will never be fully understood.
A Changing Landscape
Fossils provide evidence about changes in the Earth's crust over time, including shifting land masses, mountain formations and other movements since the fossils were deposited. Scientists can discern how the Earth's current surface came to be by examining similar plant and animal fossils found in sedimentary rocks of the same time period from different areas of the world. Fossils of several different ages found at fractures and faults in adjacent localities offer evidence of this movement of the Earth's crust, even if the change is not obvious to the naked eye.
Evidence for Evolution
Without fossils, there would be no record of the beginning, progression and continuing evolution of life that has been occurring on Earth over millions of years. Knowledge of extinct organisms would have been lost to time, and any understanding of modern plants and animals would be learned only from existing species. Fossils remain critical in understanding the evolution of life on Earth as well as the planet itself, and they have revealed information on the developments of shells and bones, when mammals first appeared, when animals began to take flight and periods of mass extinctions on our planet.
Tags: about Earth, about Earth history, Earth crust, Earth history, evolution life
