Paleontology is the Science that is the study of prehistoric life from their fossilized remains. It also includes the history of the earth, organisms found in it, and their supposed evolution.
Fossils are the remains of living thing buried and found in rocks. Some are just imprints of the organism left in rocks, these are most often the fossils of invertebrates and plants. Others are the actual mineralized remains of the organism most often these fossils are of vertebrates. Interpreting fossils is a combination of biology and geology because they show the type of organism that left the fossil and how it relates to other organisms. The problem is that this makes the interpretation of fossils highly dependent on theories of both biology and geology. As a result any theoretical errors in biology and geology will result in errors fossil interpretation.
By studying fossils Paleontology has produced many interesting results however like all historical science the accuracy of those results are highly dependent upon the theories used to produce them. Paleontology is highly dependent on two other fields of science and the accuracy of their theories that is the sciences of Geology and Biology.
Paleontology requires making assumptions about the past which are based in philosophy and rather than science. It needs to be realized that examining the same fossils and rock with a different set of philosophical assumptions will produce different interpretations.