Lecture 14C

Lecture 14C - 1 T e r t i a r y MESOZOIC 250 mya - 65 mya...

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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 (ancient 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) 180 km in diameter, meteor 10 km smoking gun for the impact hypothesis fire, dust, tidal waves, temperature changes, acid rains, etc Mesozoic mammals Coexisted with dinosaurs for more than 100 million years. During the Mesozoic, most mammals - small Alphadon (Cretaceous) T e r t i a r y CENOZOIC 65 mya - present Tertiary & Quaternary Periods Cenozoic Era Indricotherium Age of Mammals? Ground sloth 3 late Cenozoic Era Epochs 1. Pleistocene (1.8 mya - 10,000) 2. Holocene (last 10,000 years) Wooly mammoth Pleistocene Epoch (1.8 mya 10,000 ya) Pleistocene Epoch (1....
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Lecture 14C - 1 T e r t i a r y MESOZOIC 250 mya - 65 mya...

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