Historical Geology

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Historical Geology
Lecture 15 Early Paleozoic Life
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Early Paleozoic Life
I Geologic Setting II Ecosystem Development A)
The Cambrian Fauna B) The Paleozoic
Fauna III The Cambrian Period A) The Cambrian
Explosion B) Windows into the Past 1)
Chengjiang Lagerstatten 2) Burgess Shale C)
The Cambrian Fauna IV The Ordovician Period A)
Ordovician Life B) Ordovician Mass Extinction
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Ecosystems
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Early Paleozoic Faunas
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Early Paleozoic Life The Cambrian Period
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Cambrian Life The Cambrian Explosion
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Cambrian Life Windows into the Past- The
Lagerstatten
Lagerstatten "(fossil) deposit places"
geological fossil deposits that are rich with
varied, well-preserved fossils, representing a
wide variety of life from a particular era.

• Chengjiang
• Burgess Shale

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Cambrian Life Chengjiang Lagerstatten
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Cambrian Life Chengjiang Arthropoda
Sinoburius lumaris (Hou, Ramskold, and Bergstrom,
1997)
Canadaspis laevigata (Hou and Bergstrom, 1997)
Fortiforceps foliosa (Hou and Bergstrom, 1997)
Xandarella spectaculum (Hou, Ramskold, and
Bergstrom, 1997)
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Historical Geology
Cambrian Life Chengjiang Arthropoda
Leanchoilia illecebrosa (Hou, 1987)
Squamacula clypeta (Hou and Bergstrom, 1997)
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Cambrian Life The Burgess Shale
Species assigned to commonly recognized groups
Thaumaptilon walcotti
Sidneyia inexpectans
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Cambrian Life The Burgess Shale
Species assigned to commonly recognized groups
Canadia spinosa
Ottoia prolifica
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Cambrian Life The Burgess Shale
Species assigned to commonly recognized groups
Hallucigenia sparsa
Karen Carr
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Cambrian Life The Burgess Shale
Other "recognized" species with no living examples
Marella splendens
Haplophrentis carinatus
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Cambrian Life The Burgess Shale
Unassigned forms
Anomalocaris canadensis
Wiwaxia corrugata
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The Cambrian Fauna

• Trilobites
• Archaeocyathids
• Inarticulate Brachipods
• Archaic Molluscs
• Eocrinoids

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Cambrian Life Ecological Complexity
Cambrian marine community
Ediacaran marine community
Carnivores Suspension feeders Deposit feeders
All suspension feeders (or at least passive food
gatherers)
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The Cambrian Fauna Trilobites
Olenellus thompsoni
Paradoxides harlani

• Phylum Arthropoda
• Class Trilobita
• Species gt600

Dikelocephalus minnesotensis
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The Cambrian Fauna Phylum Arthropoda
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The Cambrian Fauna Archaeocyathids

• Phylum Porifera (?)
• Diameter 25mm
• Height up to 150mm
• Reef Builder

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The Cambrian Fauna Phylum Porifera

• little cell specialization
• loose" organization
• no true organs or tissues (?)
• do not chase and capture food
• do not move
• sessile - attach firmly to a surface (substrate)
• many shapes and sizes

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The Cambrian Fauna Inarticulate Brachiopods
Mickwitzia muralensis
Lingula sp.

• Phylum Brachiopoda
• Class Inarticulata

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The Cambrian Fauna Early Mollusks
Heliconelloida sp. Class Monoplacophora

• Phylum Mollusca

Rostroconchia sp.
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The Cambrian Fauna Eocrinoids
Gogia spiralis.

• Phylum Echinodermata

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Ordovician Life Ecological Complexity
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Ordovician Life Ecological Complexity
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Ordovician Life New Niches
high energy littoral settings
Reefs
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The Paleozoic Fauna Ordovician Period

• Articulate Brachiopods
• Bryozoans
• Crinoids
• Corals
• Nautiloids
• Gastropods
• Graptolites

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The Paleozoic Fauna Articulate Brachiopods
Boardman, et al., 1987
Stearn,1989

• Phylum Brachiopoda
• Class Articulata

Characteristics
Herbertella sp. Order Orthida
marine shallow bilateral symmetry hinged
shell tooth and socket hinge
Rafinesquina sp. Order Strophomenida
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The Paleozoic Fauna Articulate Brachiopods
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The Paleozoic Fauna Bryozoans

• Phylum Bryozoa
• Class Stenolaemata
• Order Trepostomatida

Characteristics
primarily marine shallow depths all
temperatures colonial (branching or
lumpy) individual zooid size of zooid lt
1mm asexual reproduction
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The Paleozoic Fauna Bryozoan Colonies
Encrusting
Erect - dendroid
Erect - fenestrate
Erect - ramose
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The Paleozoic Fauna Fossil Bryozoans
Fossil fenestrate bryozoans
Prasopora sp.
Hallopora sp.
Archimedes sp.
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The Paleozoic Fauna Corals
Streptelasma sp. Order Rugosa
Favosites sp. Order Tabulata
Characteristics

• Phylum Cnidaria
• Class Anthozoa
• Subclass Zoantharia

marine tropical colonial or individual
(Rugosa) active reef building to 50m can survive
to 90m carbonate skeleton radial
symmetry individuals polyps
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The Paleozoic Fauna Stromatoporids

• Phylum Porifera
• Class Stromatoporoidea

Boardman, et al., 1987
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The Paleozoic Fauna Nautiloids

• Phylum Mollusca
• Class Cephalopoda
• Order Nautiloidea

Characteristics
marine shallow depths cone-shaped shell with
internal partitions straight sutures coiled or
straight carnivorous range ordovician to
holocene (1 surviving species)
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Historical Geology
The Paleozoic Fauna Gastropods
Maculites sp. Order Euomphaloidea
Salpingostoma richmondense Order
Bellerophontoidea

• Phylum Mollusca
• Class Gastropoda

Moore, et al., 1952
Characteristics
marine to fresh shallow depths all
temperatures helical, hollow shell grazer single
muscular foot
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The Paleozoic Fauna Graptolites
Mongraptus sp.

• Phylum Hemichordata
• Class Graptolithina
• Order Graptoloidea

Characteristics
marine planktonic all depths all
temperatures colonial multiple cups on central
rod each holding tiny animal
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Ordovician Mass Extinction
Causes

• Global Cooling (Glaciation) Rapid Warming
• Rapid Sea Level Changes

Losses

• Families 12
• Genera 61
• Species 85

Affected Species

• Brachiopods (33)
• Bryozoans (33)
• Trilobites
• Graptolites