Slide #1.

The Paleozoic
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Slide #2.

Cambrian Period 541-485 MYA • Named by Adam Sedgewick as a Latinized form of Welsh name for Wales (Cymru). • Period begins with the breakup of a supercontinent called Pannotia, centered on the south pole • Increase in the number of animals with hard exoskeletons. It likely began as a way to sequester Ca, but continued with larger body sizes following predation. • CO2 (~1.4%) O2 (rose to ~14%)
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Slide #4.

Ordovician Period 485-443 MYA • Named after a Celtic Welsh tribe by Charles Lapworth to resolve a fight between Sedgewick and Murchison • Transition from Cambrian marked by an extinction event • To Silurian by a more significant extinction event (~60% lost) • Continents remained southern in distribution
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Slide #5.

Silurian Period 444-416 MYA • Roderick Murchison named this rock sequence after an ancient Celtic tribe of Wales • Continental masses equatorial and began to collide • Vascular plants appeared on land • Jawless fish continued to diversify and jaws appeared
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Slide #6.

Devonian Period 419-358 MYA • Named after Devon, England by Murchison and Sedgewick • Vascular plants diversified • Vertebrates began to move onto land • End of the period marked by a series of extinctions
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Slide #7.

Carboniferous Period 358-298 MYA • Named for coal-bearing strata by William Conybeare and William Phillips • Mississippian (358-323 MYA) • Pennsylvanian (323-298 MYA) • Southern continents (Gondwana) were centered over the south pole generating a southern hemispheric ice age • Romer’s Gap (360-345 MYA) caused by mass extinction and drop in oxygen • Rise in importance of ray-finned fishes and crinoids • Gradual rise in oxygen to 35% as more carbon sequestered • Rise in terrestrial arthropods, amphibians and reptiles • Toward the end of period (~305 MYA) rainforest collapse – a minor extinction event
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Slide #8.

Permian Period 298-252 MYA • Named for the city of Per’m in the Russian Ural Mountains by Roderick Murchison • Assembly of Pangaea with large continental desert • Modern terrestrial vertebrate groups became dominant • Largest extinction event of the Phanerozoic at end of the Permian –most life extinguished
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Slide #9.

Causes of the end Permian extinction • Volcanism • Methane hydrate release • Anoxia • Hydrogen sulfide release • Influence of Pangaea
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