| Question | Answer |
|---|---|
| Eon | Longest subdivision in the geologic time scale that is based on the abundance of certain types of fossils and is subdivided into eras |
| Epoch | Next smaller division of geologic time scale is subdivided into periods is characterized by differences I life forms that may very regionally |
| Era | Second longest division in geologic time is subdivided into periods and is based on major worldwide changes in types of fossils |
| Geologic time scale | Divisions of earths history into time units based largely on the types of life forms that lived only during certain periods. |
| Natural selection | Process by which organisms that are suited to a particular environment are better able to survive and reproduce then organisms that are not |
| Organic evolution | Change of organism over geologic time |
| Pangea | Large ancient land mass that was composed of all the continents joined together |
| Period | Third longest division of geologic time is subdivided into epochs and is characterized by the types of life that existed worldwide |
| Species | Group of organism that reproduces only with other members of their own group |
| Trilobite | Organism with a three-lobed exoskeleton that was abundant in Paleozoic oceans and is considered to be an index fossil |
