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Paleozoic Era Invertebrates. Chapter 12 Part 1. Paleozoic Geology. 4 transgressions Major orogenies Mountain ranges form/oceans close + open Pangaea forms. Pre-Paleozoic life. Stromatolites Ediacaran fauna. End of the Paleozoic life. Cambrian climate .
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Paleozoic Era Invertebrates Chapter 12 Part 1
Paleozoic Geology • 4 transgressions • Major orogenies • Mountain ranges form/oceans close + open • Pangaea forms
Pre-Paleozoic life • Stromatolites • Ediacaran fauna
Cambrian climate • What is the climate like coming out of the Proterozoic? • Where are most of the continents located?
Cambrian • Animals with skeletons appear, abruptly • Cambrian explosion • Why?
Early Cambrian fossils • Shelly fauna • Several millimeters
Why develop a calcium skeleton in the Cambrian? • Precambrian oceans low in calcium carbonate (calcite) • Theory now rejected • How to disprove?
Why develop a calcium skeleton in the Cambrian? • Metabolic systems evolving • Organism needs to eliminate mineral matter • Secret excess ions as skeleton
Why develop an exoskeleton? • Advantages?
Wounded Trilobite Cambrian predator and prey • Anomalocaris and trilobite
Marine communities • How things get around • Where they live • How they feed
Where marine animals live/how they move • Organisms live above seafloor are pelagic • Plankton are floaters • Nekton are swimmers
Where marine animals live/how they move • Organisms live above seafloor are pelagic • Plankton are floaters • Nekton are swimmers • Animal plankton: zooplankton • Plant plankton: phytoplankton
Where they live/how they move • Organisms live in/on seafloor are benthonic • Infauna (live in sediment) • Epifauna (animals) • Epiflora (plants) • Can be sessile (stationary) • Or mobile
Feeding style • Suspension feeders: catch food from water (plants, animals, nutrients) • Sediment-deposit feeders: ingest sediment • Herbivores: plant eaters • Carnivore/scavenger: meat eaters
Description • Benthonic, epifaunal, suspension feeder • Animal lives on seafloor and removes food from water
Cambrian marine community • Cambrian explosion • Experimentation!
Famous Cambrian fossil locations • Burgess Shale, British Columbia • Sauk Sea transgressing
Sands covered with black mud • Shale preserved benthonic, soft-bodied community
Why there? • Avalanche of mud off edge of coast trapped shallow-water creatures • Fine mud let soft-bodies be preserved
Trilobites • Appear in the Cambrian • Benthonic, mobile, sediment-deposit feeders
Trilobites • Member of arthropod phylum • Exoskeleton • Distinct parts to body • Jointed appendages
Trilobites • Member of arthropod phylum • Exoskeleton • Distinct parts to body • Jointed appendages
Trilobites • Max diversity by Late Cambrian
Trilobites • Extinction at end of Cambrian • Increased competition? • Increased predation? • Loss of habitat? • Cooling seas?
Cambrian Brachiopods • Two-shelled animals • Benthonic, sessile, suspension feeders • Inarticulate: muscles held shells together
Inarticulate Brachiopod • Two-shelled animals • Benthonic, sessile, suspension feeders • Inarticulate: muscles held shells together
Cambrian Archaeocyathid • Benthonic, sessile, suspension feeders • Built reef-like structures
Cambrian Archaeocyathid • Benthonic, sessile, suspension feeders • Built reef-like structures
Other fauna • Arthropod from Burgess shale
Other fauna: • Short-lived evolutionary experiments • Anomalocaris • Up to 3 feet long • Major predator
Other fauna: • Short-lived evolutionary experiments • Helicoplacus: extinct 20 Ma after appeared
Paleozoic life • Cambrian Explosion • Exoskeleton • Experimentation • Animals to know: • Trilobite • Brachiopod • Archaeocyathid