1	The Paleozoic: Early Years Cambrian- 543 to 490 ma
2	What can happen in 40 ma? Early Cambrian- “Cambrian Explosion” Rising seas flooded continents, creating shallow seas, drowning landmasses Late Cambrian- carbonate-secreting organisms flourish
3	The Cambrian Craton Late Proterozoic- By ~600 ma, Rodinia began breaking apart By Cambrian- New oceans basins formed Marine sediments were deposited across the newly rifted & subsiding margins
4	Cambrian Continents Were barren & devoid of all vegetation a barren landscape covered by blowing sand, silt & clay. Evidence: cross-stratification, extensive sorting, ripple marks Were low in relief Were characterized by raised areas (arches) and low areas (basins) Arch- broad, gentle warping of the crust Transcontinental Arch, North America- Single largest Cambrian craton feature in NA Extends from Lake Superior southwest towards AZ
5	North American Cambrian Strata Dramatically thicken from craton interior towards the margins. Continents were periodically flooded creating shallow seas Sauk transgression- Cambrian cratonic sandstone one of the most mature in the world!
6	Cambrian Climate North America was near the equator Had a warm climate Evidence- Cambrian oolites, shelly limestone & local evaporite deposits Sauk sediments reveal consistent fair weather punctuated by violent, hurricane-like storms
7	The “Cambrian Explosion” An evolutionary burst that occurred in only 40 million years!!! Most of the major phyla began Includes annelids, arthropods, brachiopods, molluscs, vertebrates, hemichordates, echinoderms and poriferans Not Bryozoa –not until early Ordivician All life was aquatic Most life was relatively small Many animals had unusual body layouts Many organisms are now extinct
8	Examples of Dominant Cambrian Life Brachiopods- (Phylum Inarticulata) Trilobites Archeocyathids Hyolithids
9	A Cambrian Sea Still-Life
10	Strange Symmetry Some Cambrian organisms display unusual forms not comparable with anything today Soft-bodied Preserved in few locales worldwide Burgess Shale, British Columbia, Canada Utah, S. China, Greenland, Siberia
11	Utah Cambrian Fossils Dawn Crinoid (Gogia spiralis), Middle Cambrian, Upper Wheeler Fm., Millard County, Utah Worm, Wheeler Fm.
12	End Cambrian