Paleozoic Era: Cambrian Period Quiz

Mesozoic Era

• Spans ~ 180 million years from 248 Ma to 65 Ma
• Divided into three periods: Triassic, Jurassic, and Cretaceous
• Often called the "age of reptiles"
• Began with much of the world's land above sea level
• Seas invaded western North America
• Breakup of Pangaea began, forming the Atlantic Ocean
• Subduction of oceanic crust produced widespread deformation, volcanism, and mountain building along the Western coast
• Mountains of western North America began forming

Mesozoic Life

• Survivors of the great Paleozoic extinction: true pines, redwoods, flowering plants, insects, and reptiles
• Reptiles adapted to the dry Mesozoic climate
• Dinosaurs dominated
• One group of reptiles led to the birds
• Many reptile groups and other animal groups became extinct at the close of the Mesozoic

Mesozoic Extinction

• Possible hypotheses: impact from large asteroid or comet, extensive volcanism
• KT Boundary (Cretaceous–Tertiary boundary) marks the end of the Cretaceous Period
• Associated with a mass extinction that destroyed a majority of the world's Mesozoic species, including all dinosaurs except for birds

Paleozoic Era

• Each period had changes in life forms, tectonics, and sea level
• Shallow seas covered the continents, and marine life flourished
• Changing sea levels contributed to diversification of life forms

Cambrian Period (543-490 Ma)

• "Cambrian explosion" – great diversity of life forms evolved during this time
• Hard-bodied organisms evolved, with the ability to secrete calcium carbonate and calcium phosphate for formation of an outer skeleton

Ordovician Period (490-443 Ma)

• Abundant and diverse marine life, including emergence of vertebrates (e.g., jawless fishes)
• Surge in rate of extinctions
• Many landmasses converged to form the southern continent of Gondwanaland

Silurian Period (443-417 Ma)

• Supercontinent of Gondwanaland near the South Pole
• Ancestral North America and Europe began converging and were situated near the equator
• Rise in sea level
• Reefs created closed basins with evaporation and evaporite deposits
• Terrestrial life: plants, scorpions, and millipedes

Devonian Period (417-354 Ma)

• Gondwanaland completely formed in the Southern Hemisphere
• North America and Eurasia joined as the continent of Laurasia in the Northern Hemisphere
• Devonian known as the "age of fishes"
• Two groups of bony fishes: lung fish and lobe-finned fish, which evolved to become the amphibians

Carboniferous Period (354-290 Ma)

• Collision of Gondwanaland with Laurasia
• Formation of the Appalachian Mountains and Ural Mountains
• Warm, moist climate
• Dense swamplands and present-day coal beds
• Insects and amniote egg

Permian Period (290-248 Ma)

• Amniote vertebrates continued to diversify
• Ancestral link to reptiles and mammals
• Permian extinction: ~95% of all marine species and ~70% of all land species
• Possible causes of extinction: redistribution of water and land, changes in landmass elevations, climate change, and lowering of sea levels