| A | B |
|---|
| variation | when an organism(s) is different from other members of the same species |
| vestigial structures | body parts that are no longer used |
| homologous structures | similar in structure and origin |
| Darwin | studied finches on islands near the coast of South America |
| sedimentary | type of rock where most fossils are found |
| fossils | remains of life from an earlier time |
| relative dating | estimating age of fossils by position in rock strata |
| mutation | must occur for evolution to take place |
| 3.5 Billion years ago | first life on earth was formed |
