History of Earth - Ordovician Period - (Paleozoic Era)

			ORDOVICIAN
			THE ORDOVICIAN PERIOD 488 TO 443 Million Years Ago
			The Age of Mollusks Warm Shallow Seas Nourish a Great Diversification of Life
". . . multiply on the earth and be fruitful and increase in number upon it." - Genesis 8:17
Cambrian							Silurian
\|-----------\| Paleo-Geography
Laurentia and Gondwana hover near equator Wide shallow seas; climate warm but later cools All land is barren, lifeless desert The period ends in ice age and extinction - possibly caused by a nearby gamma ray burst in space
Life
Mollusks develop buoyancy to float. They multiply and diversify - shelled squids, nautiloids, bivalves; snails Trilobites continue to diversify and flourish Crinoids and other echinoderms wildly multiply Corals, graptolites and brachiopods flourish Jawless fish (below right) slowly spread Red and green algae thrive First life on land - primitive liverwort plants and fungi
		An Ordovincian reef - a complex community built of algae, sponges, rugose coral, graptolites and crinoids (Image: CERC - Columbia Univ.)
					Armored cephaloid molluscs dominate Ordovician Seas (Image:John Sibbick)
				Arandaspis, (right), a primitive jawless fish. The jawless fish did not establish ocean dominance (as their descendants, the jawed fish, soon would). (Image: NatureLand)
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SOURCES: University of California Museum of Paleontology - Tour of Geologic Time Wikipedia - Geologic Time Scale Palaeos - Geological Time IInternational Commission on Stratigraphy By Corey Zak - CORZAK INTERACTIVE