-
Precambrian time 4,600
11- Nearly half of the valuable mineral deposits in the world occur in the rocks if this period.
23- Shelled brachiopods appear -
Period: to
Laura Santos p.1
Geological Timescale -
Cambrian 542
7- some scientists believe that humans kind has caused mass extinctions of plant and animal species, polluted the oceans and altered the atmosphere.
38- environmental change cause mass extinction of sea invertibrates (trilobites & eurypterids) as the sea retreat -
Ordovician 488
14-There is argument as to when this epoch began, some scientists think it began with the industrial age in the early 1800's other with the atomic age in 1950's.
28- Small rodents evolve. -
Silurian 444
31-Huge plants begin to develop , early amphibians form.
24- Eurypterids (sea scorpions), sea stars and coral became more common. -
Devonian 416
1- There is very little plant life during the period.
37- Age of fishes, fish that can breath out of the water and spend time on land form. -
Mississippian period 359
2- Swamps and forests cover the land.
10- The presence of stromatolites indicates that shallow seas covered much of the earth during intervals in this period. -
Pennsylvanian period 318
4- Giant cockroaches appear.
15- Coal deposits form. -
Permian 299
30- Colonies of tiny invertebrates call graptolites florished and vertibrates appear, fish did not have jaws or teeth and their bodies were covered with bony plates.
19-The last glacial period ended and sea levels rose, great lakes formed. -
Triassic 251
16- Welcome to the world of the dinosaur! Enter the squirrel sized dinosaur & the first forest dwelling mammals appear.
8- Appalachian Mountains are created because of the collins of tectonic plates & savannahs form. -
Jurassic 200
3- Flying reptiles called pterosaurs are in the air now.
13- Whoa those dinos are getting big & dominate the land- lizard hipped and bird-hipped appear-carnivores and herbivores have arrived. -
Cretaceous 146
33-Vascular land plants and animals, such as scorpion begin to evolve on land
37- Age of fishes, fish that can breath out of the water and spent time an land time. -
Paleocene 65.5
12- First primates evolve.
18- Various species migrated between continents across land bridges. -
Eocene 55.8
17- Flying squirrels, whales and bats appear.
26- First modern horse appear. -
Oligocene 33.9
22- Trilobites appear.
19- The last glacial period ended and sea levels rose, Great Lakes formed. -
Miocene 23.0
21- Early reptiles resembling large lizards appear.
25- World wide temperature drop about 4 degrees celsius (39.2 degrees fahrenheit) -
Pliocene 5.3
20- Species that did not evolve to survive extreme cold moved to warner climate areas of became extinct (dire wolf & giant ground sloth)
28- Morden human developed agriculture and used tools made of bronze and iron. -
Pleistocene 1.8
32- Antarctic icecaps begin to form.
34- Ichthyosaurs are living in the ocean, new invertebrates call ammonite develop. -
Holocene 0.0115
6- Himalayas develop due to uplifting caused by the indian subcontinent and eurasian continents colliding.
9- Homosapien (modern humans) appeared & are hunters.
