The Paleozoic An overview of the era from the Ordovician Period to the Permian, with maps and timelines. http://earth.usc.edu/~stott/Catalina/Ordivician.html Usc.edu~Site InfoWhoisTrace RouteRBL Check
Paleobiology: The Late Paleozoic Article on the Devonian, the coal swamps and glaciers of the Carboniferous, the Permian and the great Permian extinction. http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookPaleo4.html Maricopa.edu~Site InfoWhoisTrace RouteRBL Check