Earth History The Paleozoic Era
Paleozoic Time(544 - 245 Million Years Ago) • Bracketed by the two most important biological events in Earth’s history: • The first appearance of complex organisms • The largest mass extinction on the history of the Earth.
Paleozoic Time • There are 7 subdivisions (periods) in the Paleozoic • Cambrian (oldest) • Ordovician • Silurian • Devonian • Carboniferous (Mississippian and Pennsylvanian) • Permian (most recent)
Cambrian (544 - 490 million years ago) • During the Cambrian period, most of the major groups of organisms alive today first appeared. • The appearance of organisms was VERY rapid. • The “Cambrian Explosion” • A 5 – 10 million year period of rapid evolutionary development.
Cambrian FossilsTrilobites Elrathia Ptychagnostus Bathyuriscus Brachyaspidon Peronopsis
Cambrian FossilsBrachiopods and Echinoderms Brachiopods Sand Dollar Starfish Starfish
Unique Fossils • The Burgess Shale (Alberta, Canada) contains very unique middle Cambrian fossils. • These animals displayed rapiddiversification and existed for only a short period before they became extinct. Charles Dolittle Walcott
Burgess Shale Fossils Anomalocaris Marrella Wiwaxia
Burgess Shale Fossils Ottoia Leanchoilia
Ordovician(490 - 443 million years ago) • Most animals alive in the Ordovician were similar to those alive in the Cambrian. • Introduction of animals similar to squid. • Cephalopods
Ordovician Extinction • The Earth’s climate became much cooler in the middle Ordovician. • Glaciers covered much of the continents • Sea level dropped • Climate change, probably, was responsible for the Ordovician mass extinction. • 60% of marine organisms
Silurian(443 - 417 million years ago) • The Earth’s climate became stable and a bit warmer during the Silurian. • This allowed many new animals to appear for the first time. • Coral Reefs • First (Jawless) Fish • Land plants
Silurian Coral Reefs • What is coral? An invertebrate animal related to jellyfish. • Small marine animals that live in warm water. • They make a “skeleton” out of calcium carbonate and often live in large colonies (reefs)
Silurian Coral • Horn Coral • Horn shaped • Usually lived alone; non-reef forming • Extinct • Pipe Coral • Honey-comb shape • Often formed reefs • Extinct
Silurian Fish (Ostracoderm) • Vertebrates • Thought to be related to fish with jaws and sharks. • Ate through a ‘sucker’ mouth.
Eurypterids • Extinct group of marine organisms. • Feeding appendages in the front. • Related to modern spiders and scorpions. • NYS State Fossil
Silurian Plants • Lived near shorelines and in shallow waters • Slowly ‘invaded’ the land area by spreading in from rivers and lakes Cooksonia
Devonian(417 - 345 million years ago) • The first appearances of real “trees” • Most vegetation was small plants • Tallest plants were only about 3 feet tall • First amphibians • First wingless insects • Marine life continued • Brachiopods, coral, echinoderms, and new fish
Devonian Organisms Tree Fossil Cockroach & Tarantula similar to Devonian Arthropods Early Amphibian Fossil
Devonian Trees • Most were shorter than 1 meter tall. • Ferns, horse tails, and seed plants were common. • The first forests were present.
Devonian Insects (Arthropods) • Arthropods are the most successful type of animal on the planet. • 6 - 9 million species in a typical forest today. Not Devonian fossils
Carboniferous(354 - 290 million years ago) • Subdivided into the Mississippian and Pennsylvanian. • Lots of swamps and coal formation. • First reptiles. • Major biological revolution - the hard shelled egg!
Carboniferous Reptile Fossils • Reptiles can live on land or in water, BUT... • Amniotic egg - has a shell that allows animals to reproduce on land. • Allows reptiles to move further onto land, away from water.
Permian(290 - 245 million years ago) • Last period of the Paleozoic • Ends with the largest mass extinction in the history of the planet • Mostly affected the animals in the oceans
Permian Reptile Fossils Dimetrodon
Permian Reptiles Leanchoilia Dimetrodon
End of the Paleozoic • Largest mass extinction in Earth’s history • 90% - 95% of all marine species became extinct • Likely due to changes in the environment and competition for living space. • Colder climate = • Volcanic eruptions =