Evolutionary History

1. having died out completely and no longer alive anywhere on Earth
7. the very long time that spans the history or Earth, from the very first cellular life to the present
9. an organism's arm, leg, or wing
10. the process by which the distribution of traits in a population changes over many generations
11. the process by which species adapt to environmental changes over a very long time
14. a body structure in two or more species that features the same parts (the same bones)
17. sharing a common ancestor population
20. to receive genes from a parent
21. a trait that makes it more likely that an individual will survive in a specific environment.
22. structure a part of an organism
23. evidence of life from the past, such as fossilized bones, footprints, or leaf prints
24. a scientist who studies fossils in order to understand the ancient history of life on Earth

2. an older population from which two or more newer species descended
3. a group of individuals born and living at about the same time
4. when something stays mostly the same over time
5. a group of organisms of the same kind (in one or more populations) that do not reproduce with organisms from any other group
6. everything (living and nonliving) that surrounds an organism
8. living things, such as plants, animals, and bacteria
12. the process by which one population evolves into two or more different species
13. a more recent species that evolved from an ancestor population
15. a group of the same type organism living in the same area
16. a random change to a gene that sometimes results in a new trait
18. a related organism from a previous generation
19. a specific characteristic of an individual organism