Paleozoic Era 570,000,000 years ago to 225,000,000 years ago Life starts in the seas and moves onto land Six periods: Cambrian Ordovician Silurian Devonian.

Paleozoic EraPaleozoic Era

570,000,000 years ago to 225,000,000 years ago570,000,000 years ago to 225,000,000 years ago

Life starts in the seas and moves onto land

Six periods:CambrianOrdovician

SilurianDevonian

CarboniferousPermian

Cambrian Period (570-500 MYA)

Cambrian Explosion – Most major animal phyla are found in the fossil record (mostly aquatic invertebrates with exoskeletons).

Burgess Shale – major fossil site located in Canadian Rockies

Ordovician Period (500-435 MYA)

1st vertebrates - jawless fish (filter feeders) The vertebrate protects the spinal cord,

which carries signals from the brain throughout the body.

The lamprey of today is a parasite. The hagfish is a scavenger.

Silurian Period (435-395 MYA)

1st jawed fish (later evolved into sharks-made of cartilage).

Ozone (O3) layer formed which blocks harmful UV radiation; life could evolve on land.

1st land plants (mosses & ferns) followed by 1st land animals (arthropods-spiders & scorpions).

Devonian Period (395-345 MYA)

“Age of the Fish” (giant armored fish).

1st bony fish (scales and swim bladder for buoyancy).

Devonian Period (395-345 MYA)

1st vertebrates on land – amphibians Evolved from the lobed-fin fish which include some

species of lungfish.

Carboniferous Period (345-280

MYA)

North America is at the equator (tropical swamps form coal deposits)

Amphibians & insects dominate and become large (dragon flies-1m wing span; cockroaches-10 cm long).

1st reptiles

Permian Period (280-225 MYA)

Early Permian reptiles, Cacops in front & Casea in back.

The middle Permian reptile, Anteosaurus.

Reptiles dominate. Pangaea begins to form (Appalachian Mnts; dry climate; ice age in

the southern hemisphere) Mass Extinction (90% of all species go extinct-mostly marine

invertebrates).

Mass Extinction

One of the Big FIVE Mass Extinctions