Bio Crossword

2. Equilibrium, Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid changes.
3. Length of time required for half of the radioactive atoms in a sample to decay.
4. Life Scale, timeline used to represent Earth’s history.
8. Period, A geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago, to the beginning of the Carboniferous, 358.9 Mya.
9. Division of geologic time into which eras are subdivided.
11. Patterns, Changes in anatomy, phylogeny, ecology and behavior that takes place in clades larger than a single species.
14. Extinction, Event during which many species become extinct during a relatively short period of time.
15. Period, A geologic period and system which spans 47 million years from the end of the Carboniferous period 298.9 million years ago, to the beginning of the Triassic period 251.902 Mya.
16. Preserved remains or traces of ancient organism.
17. Term used to refer to a species that has died out and has no living members
18. Period, A geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya.
19. Evolution, Process by which unrelated organisms independently evolve simiilarites when adapting to similar environments.

1. Fossil, Distinctive fossil that is used to compare the relative age of fossils.
2. Scientist who studies fossils.
5. Process by which two species evolve in response to change in each other over time.
6. the evolution of a species by gradual accumulation of small genetic changes over long periods of time.
7. Period, A geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period, 298.9 Mya.
10. Period, A geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya.
12. Dating, Method for determining the age of a sample from the amount of a radioactive isotope to the nonradioactive isotope of the same element in a sample
13. Period, Was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago to the beginning of the Ordovician Period 485.4 mya.
20. Major division of geologic time; usually divided into two or more periods