| A | B |
|---|
| Charles Darwin | the British naturalist responsible for the theory of evolution |
| evolution | the process by which living things change over time |
| adaptation | a characteristic that helps an organism survive in its environment |
| naturalist | a scientist who studies nature |
| vestigial structures | structures from an organism's evolutionary past that have no function in the present |
| embryo | a developing organism |
| fossils | the remains of organisms that lived in the past |
| remnant | that which remains or is left over |
| speciation | the process by which two species become so different due to separation they can no longer interbreed |
| natural selection | the process by which organisms with the traits best suited for their environment survive and reproduce |
| fossil record | a historical sequence of life indicated by evidence found in layers of the Earth's crust |
| vertebrate | an animal with a backbone |
| trait | an inherited characteristic |
| generation time | the period between the birth of one generation and the birth of the next |
| species | organisms at this level can mate and produce fertile offspring |
