The Paleozoic Era
Overview
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian
Citatations
http://www.britannica.com/EBchecked/topic/439604/Paleozoic-Era/260830/Paleozoic-geography
http://www.livescience.com/37584-paleozoic-erah.tml
http://www.fossilmuseum.net/Paleobiology/Paleozoic_paleobiology.htm
http://paleobiology.si.edu/geotime/main/htmlversion/ordovician4.html