The History of Earth

4. this period known as the “age of fishes”.
5. it gave rise to the dinosaurs.
8. a porous shell containing a membrane that provided an environment for embryo.
10. It is also sometimes called the “ age of flowering plants”.
12. 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.
16. It is the subdivision of eons.
17. It is a system of chronological measurement that relates stratigraphy to time.
20. also known as the “time of hidden life”.
22. A dramatic climatic shift may have been partially triggered the assembly of smaller continents into Pangea.
25. this era is known as the “age of mammals”.
26. this is the period of visible life where rapid expansion and
29. This period marks the earliest appearance ofvertebrates and the jawless fish known as Agnatha.
30. it was largely responsible for the demise of the great coral reefs, jawless fishes and trilobites.

1. a scientist who studies the history of life on Earth through the fossil record.
2. the period just before the proliferation of complex life on Earth.
3. It appeared on Earth at some time between 3.9 billion years ago.
6. it gave rise to mammals.
7. This period brought the emergence of terrestrial life.
9. time of ancient life.
10. the formation of organic deposits of coal in plant debris formed the world’s first extensive coal deposits.
11. a primitive armoured fish with a cartilage skeleton.
13. The largest intervals of geologic time.
14. of life forms occur and fill the various ecological niches available on Earth.
15. without it life could not exist on land because of harmful ultraviolet radiation.
18. this is when almost all marine organisms came into existence as evidenced by abundant fossils.
19. Warm -- moist climate conditions contributed to lash vegetation and dense swampy forests.
21. the earliest well developed circulatory system (vascular plants).
23. it is known as the age of reptiles.
24. time of middle life.
27. time of recent life.
28. the period where life first formed on Earth, archea and bacteria.