Life starts in the seas and moves onto land Paleozoic Era Six periods: Cambrian Ordovician Silurian Devonian Carboniferous Permian 570,000,000 years ago to 225,000,000 years ago
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) • 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). Early Permian reptiles, Cacops in front & Casea in back. The middle Permian reptile, Anteosaurus.
Mass Extinction One of the Big FIVE Mass Extinctions