Paleozoic LifeCh 12 & 13

This artistic diorama modelsthe living Environmentfor the Burgess shale organisms

Visible LifeIn the Cambrian system of rocks, a large number of visible complex specieswere observed.

Life had been single-celled simple organisms for billions of years.The “sudden” appearance of large, well-preserved organisms causedscientists 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 stepsLeading 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 faunaThis 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 trilobiteshows signs healing wounds

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

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

Marine Ecosystem

Plankton:

Jelly fish

Nekton: fish

cephalopod

Benthos: d-k

Sessile epiflora:

seaweed Sessile epifauna:

bivalvecoral crinoid

Marine EcosystemMobile epifauna: gastropod, starfish

Infauna:

worm, bivalve

Marine EcosystemSuspension feeders:

bivalve

coralcrinoid

Marine Ecosystem

Herbivores: gastropodCarnivores-scavengers: starfishworm sediment-

deposit feeder

Fig. 1, p. 248

Trilobites:ConspicuousCambrianfossils

Fig. 3, p. 249

Agnostus Believed to be blind

Other trilobites haveCompound eyes

Fig. 6, p. 249

Fig. 5, p. 249

Fig. 12-9, p. 251

Middle Ordovician

Fig. 12-11a, p. 252

Late Ordovician

Fig. 12-11b, p. 252

Fig. 12-12a, p. 253

Middle Devonian Reef Buildiers

Fig. 12-14, p. 254

Middle DevonianNew York StateEurypterid

Fig. 12-15, p. 254

Late Devonian Ammonoid

Fig. 12-16, p. 255

Fig. 12-19, p. 257

http://www.youtube.com/watch?v=s1xfRc4SDsw&NR=1&feature=fvwp