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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 • 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 & supercontinents • 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 Era 2.5 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, Achaean multicellular plants, First plants & soft Prokaryotic life bodied animals in Little O2 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 monkeyFirst human Last Dinosaurs First bird Flowering Plants First Mammals First Dinosaurs Review of last 248 Million years Review 1. 2. 3. 4. 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?