| A | B |
|---|
| Fossil | A trace of a long dead organism. |
| Sediment | Dust, sand, or mud that is deposited by wind or water. |
| Mold | An imprint in rock in the shape of an organism. |
| Cast | When a mold becomes filled with hard minerals. |
| Law of Superposition | Successive layers of rock are deposited on top of one another by wind or water. |
| Stratum | A layer of soil or rock in a cross section of the Earth. |
| Relative age | The determination of a fossils age by comparing it to another fossil. |
| Absolute age | The age in years of a fossil determined by the amount of sediment deposited on top of it. |
| Extinct | The disappearance of organisms. |
| Mass extinctions | Brief periods during which large numbers of species disappeared. |
| Biogeography | The study of the geographical distribution of fossils and living organisms. |
| Acquired trait | A trait that is not determined by genes. |
| Natural selection | Organisms best suited for their environment reproduce more successfully than other organisms. |
| Uniformitarianism | The geological structure of the Earth resulted from cycles of observable processes and that these same processes operate continuosly through time. |
| Adapt | To change genetically over generations to become better suited to the environment. |
| Fitness | A single organism's contribution to the next generation. |
| Adaptive advantage | A favorable trait that gives that enables an organism to better fit into its environment. |
| Homologous | Similar features that originated in a shared ancestor. |
| Analogous | Structures that serve identical functions but have different embryological development. |
| Vestigial | Features that were useful to ancestors but are no longer useful to modern organisms. |
| Conserved | Features that have remained unchanged. |
| Coevolution | The change of two species in close association with each other. |
| Convergent evolution | When the environment selects similar phenotypes, even though the ancestral types were quite different from each other. |
| Divergent evolution | Two or more related populations or species become more and more dissimilar. |
| Adaptive radiation | Many related species evolve from a single ancestral species. |
| Artificial selection | Breeding of organisms by humans for specific phenotypic characteristics. |
