| A | B |
|---|
| The preserved remains or traces of an organism that lived in the past | fossil |
| Rock made of hardened sediment | sedimentary |
| A way to determine the actual age of fossils | absolute dating |
| The theory that evolution takes place slowly but steadily | gradualism |
| Describes a species that has no living members | extinct |
| The theory that species evolve during short periods of rapid change | punctuated equilibria |
| The million of fossils that scientists have collected | fossil record |
| similar structures that related species have inherited from a common ancestor | homologous |
| a diagram that shows how scientists think different groups of organisms are | branching tree |
