| A | B |
|---|
| Competition | Struggle among organisms for available resources |
| Domesticated | Tamed, Animals can be controlled by humans |
| Paleontologist | Scientist who study fossils of ancient life |
| Cretaceous | 138 Million Years Ago |
| Fossils | Remains and traces of organisms that lived long ago |
| Mutation | Change in a gene's DNA |
| Cast Fossil | Formed by hardening minerals or plaster of Paris |
| Evolution | Idea that new species developed from earlier species |
| Selective Breeding | Desirable Characteristics |
| Permian | 290 Million Years Ago |
| Cambrian | 600 Million Years Ago |
| Petrification | Changing of the hard parts of a dead organism to stone |
| Mold Fossil | Hollowed Space in the shape of an organism or one of its pieces |
| Extinct | Species No Longer Exists |
| Era | Major Division of Geologic Time |
| Endangered | Population numbers are so low that they are in danger of becoming extinct |
