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Paleozoic Life

Paleozoic Life. Invertebrates. Major invertebrate phyla evolved in the Cambrian Trace fossils common Echinoderms diverse Trilobites, inarticulate brachiopods, archaeocyathids –major skeletonized animals. Paleozoic Life – Introduction. Tectonics important role on evolution.

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Paleozoic Life

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  1. Paleozoic Life Invertebrates

  2. Major invertebrate phyla evolved in the Cambrian • Trace fossils common • Echinoderms diverse • Trilobites, inarticulate brachiopods, archaeocyathids –major skeletonized animals

  3. Paleozoic Life – Introduction • Tectonics important role on evolution • Opening and closing of ocean basins • Transgressions and regressions of epeiric seas • Change positions of continents • Evolution • Skeletonized animals appear (PreЄ- Є boundary) • Marine invertebrates diversify • Vertebrates also evolved • Organisms move from water to land • Major Extinctions (end of Paleozoic) • Marine invertebrate community • Many amphibians and reptiles on land

  4. The First Shelled Fossils • Mineralized skeleton appeared abruptly – Why? • Cambrian organisms complex • Multi-celled organism must’ve had pre-Є history • Lacked hard parts; did not leave a fossil record • Ediacaran Fauna (570-670 Ma) • 1st multi-celled organism • Skeletons of chitin, silica, & CaCO3

  5. Early Cambrian Emergence of Shelly Fauna • Low diversity • Composed of CaCO3 & Ca3(PO4)2 • Fauna had fully developed features • Anatomies indicate extended evolution • Extended from Cambrian to Ordovician

  6. Early CambrianShelly Fauna Abrupt Appearance • Possible explanations • Changes in ocean chemistry • Deficient in Ca & PO43- = no hard parts • Rejected; numerous carbonate rxs and phosphate deposits • Invertebrates need to eliminate mineral matter

  7. CambrianSkeleton Advantages • Protect against UV radiation • Move into shallower H2O • Prevent dry out • Protect against predators • Skeleton for support; increase size • Attachment site for muscles Injured Trilobite

  8. Middle CambrianShelly Fauna • Many invertebrate groups evolved • Cambrian Marine Community • Brachiopods (still around) • Archeocyathids • Trilobites

  9. Middle CambrianMarine Community • Brachiopod • Primitive type • Inarticulate (chitin phosphate) • Hinged by muscles • Present type • Articulate • Archeocyathids • Benthonic, sessile, suspension feeder • Made reef structure • Trilobites most common • Benthonic, mobile, sed dep feeder, crawled or swam • Echinoderms

  10. Middle CambrianBurgess Shale • Sauk Transgression • Black, anoxic seds • Soft-bodied organisms preserved • Fossils classified into existing phyla • Most fossil in mid-Є, but fewer species • Strange fossils • No living counterparts – extinct? • Reassigned to known phyla

  11. Cambrian Worm Cambrian Arthropod Cambrian Worm Middle CambrianBurgess Shale

  12. Graptolites Graptolites Acritarchs Ordovician • Major transgression warm water • Increased diversity • Epifaunal, benthonic, sessile, susp feeders • Articulated brachs • Reef Builders • Bryozoans • Tabulate/Rugose corals • Stromatoporids • More abundant • Graptolite - plankton • Conodont - tooth like CaPO43-

  13. End of Ordovician • Mass Extinction • 100’s of families did not make it to Silurian • 50% of brachiopods and bryozoans died • Maybe glaciation in Gondwana

  14. Silurian & Devonian • Rediversification • After Ordovician extinction • Major reef building • Tabulate/rugose corals • Stromatoporids • Common guide fossils • Euryterids • Ammonites

  15. End of Devonian • Mass Extinction (L. Frasnian – Famennian) • Lose most reefs • Decline of many organisms • Brachiopods, ammonites, acritarchs, gastropods, bryozoans • Mostly tropical groups; not polar • Possible Causes • Global cooling; Iapetus closing

  16. Mississippian Ammonoid Permian Fusilinid Carboniferous & Permian • Rediversification • After Devonian extinction • Brachiopods & ammonites • Small, patchy reefs • Crinoids, blastoids, brachs, bryozoas • Permian life restricted • Seas regressed • Fusilinids diverse

  17. End of Permian • Mass Extinction • 50% marine families • 90% marine invertebrates • Possible Causes • Regression • Less living area • Pangaea forms • Continental suturing • Decreased S ‰ • Arid climate • Evaporite formation

  18. Other Permian Extinction Possibilites • Climate Change • Warming at close of Permian • More CO2 in atmosphere • More volcanism • Changes in ocean ciruculation brings CO2 to surface/atmosphere • Meteorite Impact

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