| A | B |
|---|
| Palenotologist | scientist who studies fossils |
| Fossil record | preserved remains or evidence of an ancient organism |
| Extinct | term used to refer to a species that has died out |
| Relative dating | method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock |
| Index fossil | distinctive fossil used to compare the relative age of fossils |
| Half-life | length of time required for half of the radioactive atoms in a sample decay |
| Radioactive dating | technique in which scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains |
| Geological time scale | scale used by paleontologists to represent evolutionary time |
| Era | one of several subdivisions of the time between the Precambrian and the present |
| Period | unit of time into which eras are subdivided |
| Proteinoid microsphere | tiny bubble, formed of large organic molecules, that has some characteristics of a cell |
| Microfossil | microscopic fossil |
| Endosymbiotic theory | theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms |
| Mass extinction | event in which many types of living things become extinct at the same time |
| Macroevolution | large-scale evolutionary changes that take place over long periods of time |
| Adaptive radiation | process by which a single species or small group of species evolves into a different forms that live in different ways; rapid growth in diversity of a group of organisms |
| Convergent evolution | process by which unrelated organisms independently evolve similarities when adapting to similar environments |
| Coevolution | process by which two species evolve in response to changes in each other |
| Puntuated equilibrium | pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change |
