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) – Skeletons of chitin, silica, & CaCO 3  1 st multi-celled organism

5. Early Cambrian Emergence of Shelly Fauna Low diversity Composed of CaCO 3 & Ca 3 (PO 4 ) 2 Fauna had fully developed features – Anatomies indicate extended evolution – Extended from Cambrian to Ordovician

6. Early Cambrian Shelly Fauna Abrupt Appearance Possible explanations – Changes in ocean chemistry  Deficient in Ca & PO 4 3- = no hard parts  Rejected; numerous carbonate rxs and phosphate deposits – Invertebrates need to eliminate mineral matter

7. Cambrian Skeleton Advantages Protect against UV radiation – Move into shallower H 2 O Prevent dry out Protect against predators Skeleton for support; increase size Attachment site for muscles Injured Trilobite

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

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

10. Middle Cambrian Burgess 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. Middle Cambrian Burgess Shale Cambrian Worm Cambrian Arthropod

12. Ordovician Major transgression  warm water Reef Builders More abundant – Increased diversity  Epifaunal, benthonic, sessile, susp feeders  Articulated brachs  Bryozoans  Tabulate/Rugose corals  Stromatoporids  Conodont - tooth like CaPO 4 3-  Graptolite - plankton Acritarchs Graptolites

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 Major reef building Common guide fossils – After Ordovician extinction – Tabulate/rugose corals – Stromatoporids – 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. Carboniferous & Permian Rediversification – After Devonian extinction – Small, patchy reefs – Brachiopods & ammonites Permian life restricted  Crinoids, blastoids, brachs, bryozoas – Seas regressed – Fusilinids diverse Mississippian Ammonoid Permian Fusilinid

17. End of Permian Mass Extinction – 50% marine families  90% marine invertebrates – Regression Possible Causes  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