1
Q
Name the time periods
A
Precambrian
Paleozoic
Mesozoic
Cenozoic
2
Q
Explain Precambrian
A
4600 million years ago
First multi-called organisms
Precambrian shields are formed
First single-felled organisms
3
Q
Explain Paleozoic
A
570 million years ago Periods when large parts of North America are covers by shallow seas -large swamps -Appalachians formed -age of amphibians and fish -first insects -first plants and animals appear on land
4
Q
Explain Mesozoic
A
245 million years ago
- shallow seas in the interior of North America at various times
- formation of Rocky Mountains begins
- innuitian mountains formed
- first bird and mammals
- age of reptiles
- first flowering plants
5
Q
Explain Cenozoic
A
66 million years ago
- formation of the Rocky Mountains completed
- continents take on their present shape
- humans begin to develop
- modern forms of life evolve
- age of mammals
- ice sheets cover much of North America
