Lecture 16 History of EARTH

Lecture 16 History of EARTH - 1 T e r t i a r y MESOZOIC...

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Unformatted text preview: 1 T e r t i a r y MESOZOIC 250 mya - 65 mya *dinosaurs *forests of fern-like plants shift to forests of gymnosperms (plants with seeds) *angiosperms (flowering plants) appear Mesozoic Era Triassic, Jurassic, Cretaceous periods “Age of Dinosaurs” Cycad, gingko, conifers (gymnosperm) End of Mesozoic Era - mass extinction boundary of Cretaceous/Tertiary periods (K/T) 65 million years ago Dinosaurs wiped out. Why? Why did K/T extinctions happen? Impact hypothesis - giant meteor hit earth K-T boundary (65 mya) Walter and Louis Alvarez Worldwide iridium layer 2 For many years, impact hypothesis was proposed, but no one could find the crater Rock that indicative of heat and/or pressure of an impact found in Caribbean K-T boundary (65 mya) Crater found near Chicxulub, Mexico (Yucatan Peninsula) Crater - 180 km in diameter; meteor - 10 km “smoking gun” for the impact hypothesis fire, dust, tidal waves, temperature changes, acid rains, etc Not everything died Mesozoic - mammals - small Alphadon...
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This note was uploaded on 12/02/2009 for the course BILD BILD 3 taught by Professor Woodruff during the Fall '08 term at UCSD.

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Lecture 16 History of EARTH - 1 T e r t i a r y MESOZOIC...

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