Fossils are the preserved remains of plants and animals. Fossils are usually found in the earth’s crust in either a frozen form, petrified form, or trapped in a substance like tar or amber. An example of fossils are the bones of dinosaurs that have gone extinct after a massive meteorite impacted the earth at the end of the cretaceous period. Another type of fossil is a trace fossil. These fossils are not the fossilized organism itself but they are the indirect evidence that the organism had once existed. Footprints, nests, egg shells, burrows, and coprolites are all examples of trace fossils.
Fossils are very important because fossils are the keys to understanding past environments, past climates, continental movement, the evolution of species, and index fossils. Paleontologists can find the ages of fossils by either relative dating or radiocarbon dating. Relative dating compares rocks from younger rock layer to rocks from older rock layers to
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One mechanism is genetic variation. Genetic variation can occur if new alleles get produced by mutations or if alleles sort into different combinations during meiosis than what was genetically written. The second mechanism of evolution is genetic drift. In this mechanism, alleles will either disappear as an effect to a natural event or alleles will get isolated in one sub-set of a population and will genetically vary from the original population. The next mechanism is gene flow, which is when alleles from one population migrate to another population and changes the genetic variation of both populations. Sexual selection is another mechanism of evolution that involves the passing down of more attractive and appealing traits. The final mechanism is natural selection and this mechanism is the most important for evolution. Natural selection is the selection of individuals that possess more favorable traits in an environment. These favorable traits will be passed down to future