Overview of natural history

Breakdown of time Different periods of Earth’s history are broken into sets of time –just like a year is broken into months, weeks, days and hours Earth history is broken into eons, eras, periods, epochs

Eons – Millions and Billions of years Haden: Earth before life evolved 4.6 to 3.5 Billion years ago (13% of Earth’s history) Achaean: Earth with only bacteria like cells 3.5 to 2.5 Billion years ago (28% of Earth’s history) Proterozoic: Multicellular life forms 2.5 BYA to 540 MYA (48% of Earth’s history) Phanerozoic: Dinosaurs to now 540 MYA – present day (11% of Earth’s history)

How time periods are distinguished Major geological events: The movement of tectonic plates to form continents & super- continents Changes in climate: a change from an ice ace to a warming period Mass extinctions or explosions: Changes in the types of life forms on earth

Haden Eon BYA So hot that the rock was molten & Water was vapor Lifeless, little O 2 in the atmosphere Relative to a calendar year: Jan 1 st – Feb. 25 th

Achaean Eon BYA Earth cooled enough to have a crust & ocean Life forms in the sea Bacteria & photosynthetic blue-green algae Feb. 25 th - April 17 th

Proterozoic Eon: Precambrian Era 2.5 BYA – 540 MYA Super continent Rodinia 21% O 2 in Atmosphere First complex cell -July 13 th First multicellular organism (seaweed/algae) –Aug 31 st

Haden lifeless Earth Achaean Prokaryotic life Little O 2 Review of Earth’s first 3.9 Billion years Proterozoic Eukaryotic life, multicellular plants, First plants & soft bodied animals in oceans later vascular plants fish, arthropods in ocean Insects, amphibians & reptiles on land

Paleozoic Era From the Cambrian explosion to the dawn of the dinosaurs

Cambrian - Permian period:540 MYA – 248 MYA Cambrian: Starts with a burst of new life forms & all life in ocean Plants & animals evolved from simple seaweed & sponges to fish in the oceans & insects, amphibians, and early reptiles on land 1 Mass extinction in the ocean Nov. 17 – Dec 6

Triassic period to Holocene Epoch 248 MYA – present From the early dinosaurs to extinction 65 MYA 1 st mammals, birds, and flowering plants The ice age to modern civilization Dec 7 th - Midnight Dec 31 st

Review of last 248 Million years First Dinosaurs Last Dinosaurs Flowering Plants First Mammals First bird First monkey First human

Review 1.What was the surface of the earth like during the Haden Era? 2.During which era did multicellular life evolve? 3.Which is a shorter period of time and eon or an era? 4.Which came first birds or mammals?