Geologic Time

3. Mesozoic marine reptiles with small heads, long necks, and flippers
4. the most recent epoch that began 10,000 years ago
8. the first epoch of the Quaternary period
10. dominant Mesozoic land vertebrates that walked with legs positioned directly below their hips
12. large mammals of the Cenezoic era
13. an ancient landmass which seperated into present-day continents
14. a large division of geologic time that is smaller than an eon
15. is a body of water fromed when ocean water floods continents
16. Mesozoic flying reptiles with large, batlike wings
17. a division of geologic time smaller than a period
20. is the seperation of a population of organisms from the rest of its species due to some physical barrier, such as a mountain range or an ocean
21. a time when a large population of Earth's surface is covered by glaciers

1. are grooves made by rocks carried in glaciers
2. the middle era of the Phanerozoic eon
5. is the youngest era of the Phanerozoic eon
6. the oldest era of the Phanerozoic eon
7. a unit of geologic time smaller than an era
9. an oxygen-poor environment where, over time, plant material changes into coal
11. the extinction of many species on Earth within a short period of time
18. the longest units of geologic time
19. connects two continents that were previously seperated