Information in the fossil records are incomplete, scientists are left with certain biases concerning fossil preservation. Fossils are the preserved remains of organisms that are found in rocks. They give clues to how the earth has evolved in geologic past, and the nature of organisms that lived during that period in time. A lot of biases are known with fossil preservation as a geologic record might not tally with the phylogenic relationship developed by biologists. Some fossils can become lost in the geologic record due to the dynamic nature of our planet. Earth materials can be eroded and weathered causing preserved fossils to be lost and exposed. Some organisms are naturally favored due to their physiology to be preserved as fossils in the geologic record. Others would be lost. This makes records of life in preserved as fossils highly subjective.