Chapter 19 Vocabulary

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Across
  1. 5. researchers who study fossils about ancient life
  2. 7. the evolution of a species by gradual accumulation of small genetic changes over long periods of time
  3. 8. Theory/ process by which two species evolve in response to changes in each other over time
  4. 12. Dating/ method of determining the age of a fossil by comparing its placement with that of fossils in other rock layers
  5. 13. a living thing.
  6. 15. Fossil/ distinctive fossils used to establish and compare the relative ages of rock layers and the fossils they contain.
  7. 16. name/ a name used by scientists that consists of an organisms genus and species
  8. 19. major division of geologic time (later divided into periods)
  9. 20. key/a series of question or statement sets that is used to identify organisms or objects.
  10. 22. the time required for half of the radioactive atoms in a sample to decay
  11. 23. Extinction/ extinction caused by slow and steady process of natural selection
Down
  1. 1. Radiation/ process by which a single species or a small group of species evolves into several different forms that live in different ways
  2. 2. a died out species
  3. 3. a classification subdivision of a family of organisms.
  4. 4. Patterns/ changes in anatomy, phylogeny, and behavior that take place in clades larger than a single species
  5. 6. Equilibrium/ pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
  6. 9. a distinguishing characteristic or quality.
  7. 10. process by which two species evolve in response to changes in each other over time
  8. 11. division of the geologic time into which eras are subdivided
  9. 12. Dating/ method of determining the age of a sample from the amount of a radioactive isotope to the nonradioactive isotope of the same element in a sample
  10. 14. a group of organisms sharing similar traits that are capable of breeding fertile offspring
  11. 17. Evolution/ process by which unrelated organisms independently evolve similarities when adapting to similar environments
  12. 18. Extinction/ event during which many species become extinct during a relatively short period of time
  13. 21. Tectonics/ geologic processes resulting in plate movement
  14. 24. Time Scale/ a timeline of Earth's history