Phanerozoic eon mesozoic era permian extinction marks

Phanerozoic Eon: Mesozoic Era
➢ Permian extinction marks boundary between Paleozoic and
Mesozoic eras
➢ The Age of Dinosaurs: Its rise and fall
➢ Consistently hot climate and dry terrestrial environments,
little if any ice caps at poles

❖ Phanerozoic Eon: Mesozoic Era: Triassic Period
➢ 248-206 mya
➢ Reptiles plentiful: crocodiles and turtles
➢ First dinosaurs
➢ First true mammals
➢ Gymnosperms dominant land plant
➢ Volcanic eruptions led to global warming and mass
extinctions near the end
❖ Phanerozoic Eon: Mesozoic Era: Jurassic Period
➢ 206-144 mya
➢ Gymnosperms continued to be dominant
➢ Dinosaurs dominant land animal
■ Some attained enormous size
➢ First known bird
➢ Mammals present but not prevalent
❖ Phanerozoic Eon: Mesozoic Era: Cretaceous Period
➢ 144-65 mya
➢ Dinosaurs still dominant on land
➢ Earliest flowering plants, angiosperms
➢ Another mass extinction at the end of the period
➢ Dinosaurs (except birds) and many other species died out
➢ Large meteorite/asteroid or volcanic eruptions blamed
❖ The Cretaceous Mass Extinction
➢ Likely meteorite impact at 65.5 mya, Mesozoic/Cenozoic
boundary
➢ Organisms that went extinct include about half of all marine
species and many terrestrial plants and animals, including
most dinosaurs
➢ The presence of iridium in sedimentary rocks suggests a
meteorite impact about 65 million years ago
➢ Dust clouds caused by the impact would have blocked
sunlight and disturbed global climate
❖ Phanerozoic Eon: Cenozoic Era
➢ Spans most recent 65 million years

➢ Tropical conditions replaced by a colder, drier climate
➢ Sometimes called The Age of Mammals
➢ Amazing diversification of birds, fish, insects, and flowering
plants
❖ Phanerozoic Eon: Mesozoic Era: Tertiary Period
➢ • 65-1.8 mya • Mammals that survived expanded rapidly •
Birds and terrestrial insects diversified • Angiosperms
become the dominant land plant • Fish diversified, sharks
become abundant • Whales appeared • Hominids appeared
about 7 mya
❖ Phanerozoic Eon: Mesozoic Era: Quaternary Period
➢ 1.8 mya to present
➢ Periodic ice ages cover much of Europe and North America
➢ Widespread extinction of many species
➢ Certain hominids become more human-like
➢ Homo sapiens appear 130,000 years ago
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