| A | B |
|---|
| evolution | change (in species) over time |
| extinct | having died out; leaving no more left |
| fossil | preserved remains or evidence of a living thing |
| fossil record | most complete biological record of life on earth |
| half-life | time it takes for half the atoms of a radioactive element to decay |
| homologous structures | structure that evolved from similar body parts |
| law of superposition | law that states younger sedimentary rock layers lie on top of older |
| macro-evolution | theory that all living things on earth arose from a common ancestor |
| micro-evolution | theory based on observation: changes take place within a species |
| radioactive dating | method based on radioactive decay of elements to date fossils or rocks |
