Across
- 2. is a characteristic that can be passed from parent to off-spring through genes.
- 4. the remains or imprints of once living organism found in layers of rock
- 7. the species of hominids that include modern humans and their closest ancestors and that first appeared out 100,000 to 160,000 years ago.
- 8. began about 251 million years ago and lasted about 185.5 million years ago.
- 10. the time of the formation of earth 4.6 billion to 542 million years ago.
- 12. a calendar that scientists use to outline the history of life on earth
- 15. estimating the age of rocks and fossils.
- 16. a group of organisms that can mate with one another to produce fertile off-spring
- 19. the theory that explains how large pieces of the crust moves and change shape.
- 20. a historical sequence of life indicated by fossils found in layers of the Earth's crust.
- 21. the process by which organisms that are better adapted to their environment survive and reproduce more successfully than less adapt organisms do.
- 22. A characteristic that helps an organism survive and reproduce in its environment.
Down
- 1. began about 542 million years ago and ended about 251 million years ago.
- 3. began about 65 million years ago and continues today.
- 5. the formation of new species as a result of evolution.
- 6. a method that measures the age of fossils or rocks in years
- 9. the process in which humans select which plant or animal to reproduce based upon certain desired traits
- 11. includes only humans and their human like ancestors.
- 13. a species that has died out completely
- 14. the average time between one generation and the next.
- 17. the process in which populations gradually change over time
- 18. a group of mammals that include humans, apes, monkeys, and lemurs.