The Mesozoic Era

Biblical Reference He who forms the mountains, who creates the wind, and who reveals his thoughts to mankind, who turns dawn to darkness, and treads on the heights of the earth— the Lord God Almighty is his name.. Amos 4:13

The Mesozoic Era The Mesozoic Era lasted from 251 MYA to 65 MYA. Mass extinction of the Paleozoic Era provided opportunities for drastically different life forms. –The life forms filled empty niches Three Periods –Triassic –Jurassic –Cretaceous

The Mesozoic Periods

Breakup of Pangaea Beginning of Era –Single global ocean –Single continent Triassic Period –Pangaea begins to break apart Heat beneath the continent caused it to expand Brittle lithosphere began to crack Cracks widened and continent began to split –Eventually Pangaea split into two separate landmasses - Gondwanaland and Laurasia

Seaways The climate of the Mesozoic Era was warmer than the Paleozoic Era. With no glaciers, the oceans had more water. Mid ocean rift systems developed –Seaways widened Atlantic Ocean began forming –Triassic Period

The Triassic World

The Jurassic World

The Cretaceous World

Changing Sea Level Mid-Ocean Rift systems responsible for rise in sea level –Hot magma displaced seawater as new rock was formed Sea Level dropped at the end of the Triassic Period Desert-like conditions formed in Western North America Sea level rose again in Jurassic Period Continued to rise in Cretaceous Period

Changing Sea Level Sea level rose during most of the Mesozoic Era.

Effects of Changing Sea Level A beach environment covered the continents’ margins.  Resulting sandstone covered by shale and limestone deposits that included the first corals, building organic reefs.  Organic reefs are structures composed of carbonate skeletons made by living organisms.  Reefs affect the environments in which they grow.  Many new organisms evolved.

The Great Lakes area of North America contains huge deposits of Silurian-aged evaporite minerals, including halite, anhydrite, and gypsum that are mined commercially.

Mesozoic Geography Throughout the Mesozoic era, the North American continent moved westward. Its western edge collided with several small landmasses carried on an ancient oceanic plate. The Rocky Mountains began forming from this collision.

The Rocky Mountains

Mesozoic Life

Phytoplankton –Microscopic organism at the base of the marine food chain –Abundant during Cretaceous –White Cliffs of Dover: Chalk deposits from remains of shells

Life Moves to Land For the first time in the history of life on Earth, land was colonized during the Mesozoic. –Fossilized plant parts and spores suggest that some form of land plant existed during the Late Ordovician.

Mesozoic Plant Life As temperatures warmed, plant life changed –Tall cycad trees –Seed plants with true flowers –Ginkgoes –Pine trees –Conifers Vascular plants have tissue for circulating water and nutrients through their stems and leaves. –The development of vascular tissue allowed plants to spread out on land.

Mesozoic Plant Life By the Late Devonian, three important groups of vascular spore-bearing plants were living on land: ferns, sphenopsids, and lycopods. –During the Late Devonian, seed ferns developed. –The most important aspect of these plants was the development of seeds, which allowed plants to spread out and colonize dry land.

Terrestrial Animals – Late Triassic Mammals –Same time as dinosaurs –Remained small during Mesozoic Era Amniotic Eggs –Contain food and water required by developing embryo

Mesozoic Reptiles Turtles Crocodiles/Alligators Lizards Ichthyosaurs (large marine reptiles) Pterosaurs (large flying reptiles) Dinosaurs (land dinosaurs)

Two Groups of Dinosaurs Ornithischian –Hips were similar to modern bird hips –Carnivorous short-necked –Herbivorous, long-necked Saurischian –Hips were similar to reptile hips –Herbivorous with grinding-teeth –Herbivorous without grinding-teeth

Flying & Swimming Animals Plesiosaurs: Mesozoic marine reptiles with small heads, long necks, and flippersPlesiosaurs Pterosaurs: Mesozoic flying reptiles with large, batlike wingsPterosaurs

Mass Extinction Devastated terrestrial dinosaurs –Most marine reptiles –Plants Today’s theory –Massive and volcanism and large meteorite (10 km diameter) impact caused climate problems –Occurred at end of Cretaceous –Caused long lasting greenhouse warming –Layer of clay from that time contains high amounts of iridium Rare on Earth but common in asteroids

Mass Extinctions

What organisms went extinct? All dinosaurs All pterosaurs All ichthyosaurs Many terrestrial plants Many marine animals

What organisms survived? Mammals Birds Trees with flowers Many plants (ferns were the most successful plant for a while) Small lizards/crocodiles/alligators/turtles Fish, squids, sharks, etc.

Australia’s First 4 Billion Years

A.the breakup of Pangaea B.Cretaceous extinction event C.formation of the Rocky Mountains D.an ice age What was the dominant geologic event of the Mesozoic era? Pop Quiz

A.the Cambrian came to an end B.dinosaurs slowly went extinct C.sea levels fell D.sea levels rose What occurred during most of the Mesozoic Era? Pop Quiz

A.fish B.mammals C.plesiosaurs D.pterosaurs Which was a Mesozoic flying reptile with large, batlike wings? Pop Quiz