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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 .
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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 4.6-3.5 BYA • So hot that the rock was molten & Water was vapor • Lifeless, little O2 in the atmosphere • Relative to a calendar year: • Jan 1st – Feb. 25th
Achaean Eon 3.5-2.5 BYA • Earth cooled enough to have a crust & ocean • Life forms in the sea • Bacteria & photosynthetic blue-green algae Feb. 25th - April 17th
Proterozoic Eon: Precambrian Era2.5 BYA – 540 MYA • Super continent Rodinia • 21% O2 in Atmosphere • First complex cell -July 13th • First multicellular organism (seaweed/algae) • Aug 31st
Review of Earth’s first 3.9 Billion years Haden lifeless Earth Proterozoic Eukaryotic life, multicellular plants, Achaean Prokaryotic life Little O2 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 • 1st mammals, birds, and flowering plants • The ice age to modern civilization • Dec 7th - Midnight Dec 31st
First human First monkey Last Dinosaurs First bird Flowering Plants First Mammals First Dinosaurs Review of last 248 Million years
Review • What was the surface of the earth like during the Haden Era? • During which era did multicellular life evolve? • Which is a shorter period of time and eon or an era? • Which came first birds or mammals?