The History of Earth

4. It is also sometimes called the “ age of flowering plants”.
5. a porous shell containing a membrane that provided an environment for embryo.
11. the formation of organic deposits of coal in plant debris formed the world’s first extensive coal deposits.
14. the period just before the proliferation of complex life on Earth.
16. a primitive armoured fish with a cartilage skeleton.
18. The largest intervals of geologic time.
24. the period where life first formed on Earth, archea and bacteria.
25. This period marks the earliest appearance ofvertebrates and the jawless fish known as Agnatha.
27. it gave rise to mammals.
28. a scientist who studies the history of life on Earth through the fossil record.
29. A dramatic climatic shift may have been partially triggered the assembly of smaller continents into Pangea.
30. time of recent life.
31. this is the period of visible life where rapid expansion and

1. of life forms occur and fill the various ecological niches available on Earth.
2. It appeared on Earth at some time between 3.9 billion years ago.
3. time of middle life.
6. This period brought the emergence of terrestrial life.
7. It is the subdivision of eons.
8. Warm -- moist climate conditions contributed to lash vegetation and dense swampy forests.
9. It is a system of chronological measurement that relates stratigraphy to time.
10. it is known as the age of reptiles.
12. the earliest well developed circulatory system (vascular plants).
13. also known as the “time of hidden life”.
15. this era is known as the “age of mammals”.
17. this period known as the “age of fishes”.
19. it gave rise to the dinosaurs.
20. time of ancient life.
21. it was largely responsible for the demise of the great coral reefs, jawless fishes and trilobites.
22. a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them.
23. without it life could not exist on land because of harmful ultraviolet radiation.
26. this is when almost all marine organisms came into existence as evidenced by abundant fossils.