| A | B |
|---|
| competition | struggle among organisms for resources |
| era | 1 of the major divisions of geologic time |
| evolution | the idea that all living things are descended from earlier forms of life.. |
| extinction | the disappearance of a species from the earth |
| cast fossil | afossil formed when minerals from rock move into and harden within the space left by a decaying organism |
| domesticated | tamed and/or bred to serve people's purposes |
| mold fossil | a fossil consisting of a hollow space in the shape of an organism |
| natural selection | the process by which the fittest living things survive and pass on their characteristics to their offspring |
| paleontologist | scientist who studies fossils |
| petrification | changing of the hard parts of a dead organism into stone |
| selective breeding | breeding of living things to produce offspring with certain characteristics |
| fossil | the remains or traces of a living thing,often preserved in rock |
| mutation | a change in a gene that can result in a new characteristic or trait in offspring |
| period | a division of geologic time that is shorter than an era |
