1. Paleozoic Life Ch 12 & 13 This artistic diorama models the living
Environment
for the Burgess
shale organisms

2. 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.

3. Emergence of shelly fauna This Cambrian fossil is a few mm

4. 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

5. Cambrian predator: anamalocoris

6. Olenellus, a Cambrian trilobite shows signs healing wounds

7. Marine ecosystem: plankton (phyto- zoo-), nekton, benthos, sessile, mobile, epifauna, infauna

8. Marine Ecosystem
Where and how animals and plants live in the marine ecosystem
Plankton:
Jelly fish
Sessile epiflora:
seaweed
Nekton: fish
cephalopod
Sessile epifauna:
bivalve
Benthos: d-k
crinoid
coral

9. Marine Ecosystem Mobile epifauna: gastropod, starfish Infauna:
worm, bivalve

10. Marine Ecosystem
Suspension feeders:
coral
crinoid
bivalve

11. Marine Ecosystem worm sediment- deposit feeder
Carnivores-scavengers: starfish
Herbivores: gastropod

13. Trilobites: Conspicuous Cambrian fossils Figure 1
Cedaria minor, from the Cambrian Weeks Formation, Utah, illustrates the major body parts of a trilobite.
Fig. 1, p. 248

14. Agnostus Believed to be blind Other trilobites have Compound eyes
Figure 3
Hypagnostus parvifrons, a small agnostid trilobite from the Cambrian Marjum Formation, Utah.
Fig. 3, p. 249

15. Figure 6
Schizochroal eyes from the trilobite Eophacops trapeziceps.
Fig. 6, p. 249

16. Figure 5
Holochroal eyes from the trilobite Scutellum campaniferum.
Fig. 5, p. 249

17. Middle Ordovician Figure 12.9: Middle Ordovician Marine Community.
Reconstruction of a Middle Ordovician seafloor fauna. Cephalopods, crinoids, colonial corals, bryozoans, trilobites, and brachiopods are shown.
Fig. 12-9, p. 251

18. Late Ordovician
Figure 12.11: Representative Brachiopods and Graptolites.
(a) Brachiopods are benthic, sessile, suspension feeders.
Fig a, p. 252

19. Figure 12.11: Representative Brachiopods and Graptolites.
(b) Graptolites are planktonic suspension feeders. Shown is Phyllograptus angustifolius from Norway.
Fig b, p. 252

20. Figure 12.12: Conodonts and the Conodont Animal.
(a) Conodonts are microscopic toothlike fossils. Cahabagnathus sweeti, Copenhagen Formation (Middle Ordovician), Monitor Range, Nevada (left); Scolopodus, sp., Shingle Limestone, Single Pass, Nevada (right).
Fig a, p. 253

21. Middle Devonian Reef Buildiers

22. Middle Devonian New York State Eurypterid
Figure 12.14: Silurian Brackish Water Community.
Restoration of a Silurian brackish water scene near Buffalo, New York. Shown are algae, eurypterids, gastropods, worms, and shrimp.
Fig , p. 254

23. Late Devonian Ammonoid
Figure 12.15: Ammonoid Cephalopod.
A Late Devonian-age ammonoid cephalopod from Erfoud, Morocco. The distinctive suture pattern, short stratigraphic range, and wide geographic distribution make ammonoids excellent guide fossils.
Fig , p. 254

24. Figure 12.16: Late Mississippian Marine Community.
Reconstruction of marine life during the Mississippian, based on an Upper Mississippian fossil site at Crawfordville, Indiana. Invertebrate animals shown include crinoids, blastoids, lacy bryozoans, brachiopods, and small corals.
Fig , p. 255

25. Figure 12.19: Phanerozoic Marine Diversity.
Phanerozoic diversity for marine invertebrate and vertebrate families. Note the three episodes of Paleozoic mass extinctions, with the greatest occurring at the end of the Permian Period.
Fig , p. 257