Transcript Paleozoic Life Ch 12 & 13 This artistic diorama models

Paleozoic Life
Ch 12 & 13
This artistic
diorama models
the living
Environment
for the Burgess
shale organisms
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.
Emergence of shelly fauna
This Cambrian fossil is a few mm
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
Cambrian predator:
anamalocoris
Olenellus, a Cambrian trilobite
shows signs healing wounds
Marine ecosystem: plankton (phyto- zoo-), nekton, benthos,
sessile, mobile, epifauna, infauna
Marine Ecosystem
• Where and how animals and plants live in the
marine ecosystem
Plankton:
Sessile epiflora:
seaweed
Jelly fish
Nekton: fish
cephalopod
Sessile epifauna:
Benthos: d-k
bivalve
coral
crinoid
Marine Ecosystem
Mobile epifauna: gastropod,
starfish
Infauna:
worm,
bivalve
Marine Ecosystem
Suspension feeders:
coral
crinoid
bivalve
Marine Ecosystem
worm
sedimentdeposit feeder
Carnivores-scavengers: starfish
Herbivores: gastropod
Trilobites:
Conspicuous
Cambrian
fossils
Fig. 1, p. 248
Agnostus
Believed to be
blind
Other
trilobites have
Compound
eyes
Fig. 3, p. 249
Fig. 6, p. 249
Fig. 5, p. 249
Middle Ordovician
Fig. 12-9, p. 251
Late Ordovician
Fig. 12-11a, p. 252
Fig. 12-11b, p. 252
Fig. 12-12a, p. 253
Middle Devonian Reef Buildiers
Middle Devonian
New York State
Eurypterid
Fig. 12-14, p. 254
Late Devonian Ammonoid
Fig. 12-15, p. 254
Fig. 12-16, p. 255
Fig. 12-19, p. 257
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