Mesozoic Era 251 m.y.a 65.5 m.y - SOL Review...
Transcript of Mesozoic Era 251 m.y.a 65.5 m.y - SOL Review...
Mesozoic Cenozoic notes.notebook
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March 30, 2017
Day 3Mesozoic & Cenozoic
Mesozoic & Cenozoic251 m.y.a Present
• at the end of the Permian, 90% of marine organisms and more than 70% of land organisms died.
• because resources and space were readily available, an abundance of new lifeforms appeared
Day 3Mesozoic & Cenozoic
Mesozoic Era251 m.y.a 65.5 m.y.a
• the geologic era that lasted from 251 million to 65.5 million years ago; called Age of Reptiles> lizards> turtles> crocodiles> snakes> dinosaurs
• Pangaea broke apart causes other collisions such as those that formed Sierra Nevada in California and Andes in South America
• climate was warm and humid; land covered mostly by shallow seas and marshes
Mesozoic Cenozoic notes.notebook
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March 30, 2017
Day 3Mesozoic & Cenozoic
Triassic Period251 m.y.a 200 m.y.a
• dinosaurs appear• most were about 45 m long• lush forests of cycads (conebearing treeslike palm trees)• ichthyosaurs lived in oceans• ammonite is index fossil• first mammals (small rodents) appear
Day 3Mesozoic & Cenozoic
Jurassic Period200 m.y.a 146 m.y.a
• dinosaurs become dominant life forms> ornithischians "birdhipped"
– herbivores: stegosaurus– flying reptiles: pterosaurs
> saurischians "lizardhipped"– herbivores: apatosaurus were some of largest – carnivores
Mesozoic Cenozoic notes.notebook
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March 30, 2017
Day 3Mesozoic & Cenozoic
Cretaceous Period146 m.y.a 65.5 m.y.a
• Tyrannosaurus rex: 6m tall and had huge jaws with teeth up to 15cm long
• ankylosaurs: armored; ceratopsians (horned), hadrosaurs (duckbilled)
• flowering plants, angiosperms, such as magnolias, willows, maples, oaks and walnuts became dominant
Day 3Mesozoic & Cenozoic
CretaceousTertiary Mass Extinction
• no dinosaur fossils have been found in rocks that formed after the Cretaceous
• some scientists believe changes in environment due to moving continents and increased volcanic activity were to blame
• Impact hypothesis: 65 million years ago, a giant meteorite crashed into Earth; raised enough dust to block the sun's rays for many yearscaused cooler climates, plants died and animals became extinct> dust formed a layer of iridiumladen rock
– iridium is commonly found in meteorites; very uncommon in Earth rocks
Mesozoic Cenozoic notes.notebook
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March 30, 2017
Day 3Mesozoic & Cenozoic
Cenozoic Era65.5 m.y.a Present
• current geologic era, which began 65.5 million years ago; also called Age of Mammals
• continents moved to present day positions• huge mountain ranges such as Alps and Himalayas formed• temperatures decreased during ice ages, new species adapted to life in cooler climatesmammals become dominant
• divided into two periods: Tertiary (time before last ice age) and Quaternary (began with last ice age and includes present time)
Day 3Mesozoic & Cenozoic
Paleocene & Eocene Epochs65.5 m.y.a 33.9 m.y.a
• many small rodents evolved; first primates such as tarsier which is the sole modern survivor of earlier Paleocene
• ancestor of horse evolved during Eocene; first whales, flying squirrels and bats appeared
• small reptiles flourished• World wide temps. dropped by about 4o C by end of Eocene
Mesozoic Cenozoic notes.notebook
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March 30, 2017
Day 3Mesozoic & Cenozoic
Oligocene & Miocene Epochs33.9 m.y.a 5.3 m.y.a
• Indian subcontinent began to collide with Eurasian continent, causing uplifting of Himalayas
• climate became drier and cooler; favors grasses and conebearing and hardwood trees
• most early mammals become extinct; large species of deer, pigs, horses, camels, cats and dogs flourish
• clams and snails continue to flourish• circumpolar currents form around Antarctica• late Miocene, Mediterranean Sea dries up and
refills several times• largest known land mammals exist
(sabertoothed cats)
Day 3Mesozoic & Cenozoic
Pliocene Epoch5.3 m.y.a 1.8 m.y.a
• predators evolved into modern forms (bear, dog & cat families)• herbivores such as giant ground sloth flourished• modern horses appear• Virginia State fossil, Chesapecten jeffersonius, was from this epoch• continental ice sheets begin to spread; sea level fell
> Bering land bridge appears between Eurasia and North America
Mesozoic Cenozoic notes.notebook
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March 30, 2017
Day 3Mesozoic & Cenozoic
Pleistocene Epoch1.8 m.y.a 0.0115 m.y.a
• ice sheets advanced and retreated several times; animals had characteristics allowing them to endure cold (thick fur that covered wooly mammoths and wooly rhinoceroses)
• giant ground sloths and dire wolves became extinct• earliest modern human fossils were found in sedimentary rock of this epoch; cave paintings found suggest they were hunters
Day 3Mesozoic & Cenozoic
Holocene Epoch0.0115 m.y.a Present
• Began 11500 years ago as last glacial period ended• ice sheets melted and sea level rose about 140m, coastlines took on their present shapes and Great Lakes formed