Checkpoint: Fossils and the Geologic Column
Fossils help determine the relative age of strata because when a scientist discovers that fossil they can then place a time frame of when that organism was alive. Scientist’s already have certain time frames that they follow, so when they find a fossils that are within that strata then they can determine when that organism was alive they can then place that organism into that time frame. All three of the localities which are Paradoxides pinus within the Paleozoic Era, Billingsella corrugate which is also in the Paleozoic Era, then there is Perisphinctes tiziani I believe, which is in the Mesozoic Era, and last the Dictyoclostus americanus which is located in the Paleozoic Era, all of these are within the same relative age they are found within the same time frame as each other. The only thing that was missing in the figure on pg.68 figure 3.6 was layer D this may have been because of possible erosion or it may have never deposited at all. That is very likely that it may have existed at one time, but the erosion from may have destroyed it. Although some scientists may argue that fossils are not a good way to determine the age of some organisms I feel as though it is a good way because the fossil is found in that layer of strata so therefore it should be placed in that time frame. The fossils that where found were between the Paleozoic Era and the Mesozoic Era because of this knowledge the scientist can determine that the fossils that were found are probably between 65 million years to 251 million years old. This allows scientists to see how the Earth has changed or evolved over the different Eras.
University of Phoenix. How Old Is Old? The Rock Record and Deep Geologic Time, p.68, Ch.3. Retrieved February 11, 2011 from University of Phoenix
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