Ch 12 Paleozoic Life

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Paleozoic Life Ch 12 13 This artistic
diorama models the living Environment for the
Burgess shale organisms
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Visible Life
In the Cambrian system of rocks, a large number
of visible complex species were observed. Life
had been single-celled simple organisms for
billions of years. The sudden appearance of
large, well-preserved organisms caused scientists
to use the term Cambrian Explosion Not so fast
the Cambrian period lasted for 54 million
years. Life appeared to evolve more rapidly but
there had been many steps Leading to the new life
forms. The Ediacara fossils were multi-celled
soft-bodied predecessors Increase in oxygen may
be responsible for increase in body size.Ocean
chemistry was evolving and may have increased in
calcium. Cambrian continents were apart allowing
more marine habitat. Sauk transgression created
more shallow marine habitat on shore. Global
warming was occurring.
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Emergence of shelly faunaThis Cambrian fossil is
a few mm
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What are advantages to having an exoskeleton?
Protection from UV light, allowing organisms into
shallow waters Prevents drying out in intertidal
locations Supporting skeleton (shell) allows for
increased size and attachment of
muscle Protection from predators
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Cambrian predatoranamalocoris
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Olenellus, a Cambrian trilobiteshows signs
healing wounds
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Marine ecosystem plankton (phyto- zoo-),
nekton, benthos, sessile, mobile, epifauna,
infauna
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Marine Ecosystem

• Where and how animals and plants live in the
  marine ecosystem

Plankton Jelly fish
Nekton fish cephalopod
Sessile epiflora seaweed
Sessile epifauna bivalve
Benthos d-k
crinoid
coral
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Marine Ecosystem
Mobile epifauna gastropod, starfish
Infauna worm, bivalve
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Marine Ecosystem
Suspension feeders
coral
crinoid
bivalve
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Marine Ecosystem
Carnivores-scavengers starfish
worm sediment-deposit feeder
Herbivores gastropod
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Trilobites Conspicuous Cambrian fossils
Fig. 1, p. 248
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Agnostus Believed to be blind Other
trilobites have Compound eyes
Fig. 3, p. 249
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Fig. 6, p. 249
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Fig. 5, p. 249
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Middle Ordovician
Fig. 12-9, p. 251
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Late Ordovician
Fig. 12-11a, p. 252
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Fig. 12-11b, p. 252
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Fig. 12-12a, p. 253
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Middle Devonian Reef Buildiers
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Middle DevonianNew York State Eurypterid
Fig. 12-14, p. 254
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Late Devonian Ammonoid
Fig. 12-15, p. 254
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Fig. 12-16, p. 255
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Fig. 12-19, p. 257
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