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Eras of Earth’s History. EQ: What causes changes in the Earth? How does knowing the past give us a VISION for the future?. Precambrian Time Eon. Precambrian Time Eon. 4.6 billion years ago-545 million years ago Information about this time on Earth is SCARCE - PowerPoint PPT Presentation
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Eras of Earth’s History
EQ: What causes changes in the Earth? How does knowing the past give us a VISION for the future?
Precambrian Time Eon
Precambrian Time Eon
4.6 billion years ago-545 million years ago Information about this time on Earth is
SCARCE Rocks are buried deep within Earth’s Crust Information on rocks damaged or destroyed by
Earth’s inner heat and pressure of other rock layers
Moon forms during this time
Precambrian Eon continued….
Earth originally thought to be “dead”
Volcanoes produce toxic atmosphere
Water and water Vapor that form the oceans comes from volcanoes, asteroids and comets!!!
*Precambrian Eon continued….*
Closer look at rocks show Signs of cynobacteria
Cynobacteria-changed Earth’s past atmosphere of water vapor, ammonia and methane into Nitrogen and Oxygen: STILL FOUND ALIVE TODAY in deep sea Thermal Vents and in volcanoes
Today’s atmosphere made up of nitrogen , oxygen and water vapor
Phanerozoic Eon (3 Eras)
*Paleozoic Era: 545-245m.y.a.: Basic Traits*
The longest of all the Eras on the Earth
Contains 7 periods Fossils of large organisms first found
in this era Almost all are marine environment Largest land Continent called
Gondwana (begins with 90 % of Earth’s surface covered by water)
Warm Earth; Life limited to oceans; ozone layer not fully developed: no plants on land intially
Ends with the largest mass extinction in Earth’s history (90% of all life killed)
*Why did life first start in the ocean?* More stable environment:
Water 22x heat capacity than air
UV Protection: – DNA Damaged by UV
radiation
– DNA contains all information for life
– Earth’s ozone layer just starting to develop from oxygen produced by cynobacteria
*Why did life first start in the ocean?* Gravity’s affect
neutralized -organisms would
develop in environment in which gravity would have no impact on animal’s structure– NO need for powerful
muscles to move
*Why did life first start in the ocean?* Easier to obtain
minerals and gases necessary for life
Water naturally has these items dissolved in it
Organisms could just absorb materials as water passed by
*Easier to obtain food*
Food would be suspended in 3 dimensions: filter feeding or feeding with tentacles become popular
7 periods of Paleozoic Era
Cambrian Period (545-505) – Trilobites
– Clams
– Inland seas suggest warm Earth
– Land Formation: supercontinent Gondwana; (S hemisphere)
Ordovician Period (505-438) First land plants (ferns) First vertebrates: early
fish appear Life moves into shallower
water: Suggests ozone layer almost fully developed as life moves closer to land
Laurussia seperates from Gondwana
Silurian Period (438-408) Corals Dominate World’s
Oceans Warm Earth Plants move further inland Animals now moving
further inland by way of water; fresh water fish
N. America covered by shallow sea
*Devonian Period (408-360)*
Fish dominate oceans First amphibians Signs of Earth
beginning to cool: Water retreats forcing organisms to adapt to the new changes. More land created
Mississippian Period (360-320) Amphibians dominate
land life Earth much cooler as
glaciers move southward from polar regions
Cooler Earth forces Amphibians to adapt to changes; (less water-thicker skin)
Pennsylvanian Period (320-286)
First reptiles and insects
Shallow seas over N.America almost disappeared
Cooler Earth
*Permian Period (286-245)*
Glaciers retreat Earth Warming back up Ends with largest mass extinction in fossil
record (Asteroid impact)
*Mesozoic Era *
AGE OF DINOSAURS 245-65 Million Years Ago Split into 3 major periods Triassic period (245-208 million years) Jurassic Period (208-144 million years) Cretaceous Period (144-65 million years)
Triassic Period
Marks beginning of Mesozoic Era First dinosaurs and mammals appeared
around 225 million years ago Atlantic Ocean Pangaea breaks up Flowering Plants appear Eoraptor, Plateosaurus and Teratosaurus
*Why Dinosaurs Evolve*
Environmental Factors- As Pangaea break apart each land mass gets a unique climate
Disease Influence- Diseases possible reason species die out
Competition for Food- organisms compete for same food sources; winners live losers die
Predatory Influence- animals develop defenses against Predators
Jurassic Period (208-144)
Flowering Plants and Dinosaurs dominate land Birds appear Appalachian Mountains Form Dinosaurs become more diverse from basic shapes Allosaurus Stegosaurus Diplodicus Ceratosaurus
Cretaceous Period (144-65)
Most advanced dinosaurs: Highly specialized, most successful of all dinosaur species
Modern Earth Appears Ends in Mass Extinction of Dinosaurs Tyrannosaurs, Tricerotops, Ankylosaurus,
Protocerotype, Velocoraptors, Pterodactyl
*Meteorite Theory?*
Says that asteroid/comet 3-5 miles wide struck near Yucatan Peninsula and caused Dinosaur Extinction
Iridium deposits in KT layer help support this
However, closest Dinosaur bones ever found date about 1,000 prior to event
Climate Change/Disease reason for extinction??
*Cenozoic Era*
Continents were drifting apart—present time of Earth
African plate collided with European plate creating the Alps
India slammed into Asian plate creating Himalayas
Climate was cooled causing several “ice ages”
*Mammals Survive because*
Small size easier to maintain body temperature in climate change
Ability to Hibernate during an extreme event
Mothers provide food for young from milk, No other organisms do this (mammals unique)
Cenozoic Era
Age of Mammals (65mya- present day) 2 Periods
Tertiary Period (65mya – 1.6mya)
Earth’s climate was warm and mild Ocean mammals like dolphins and whales
evolve Land-insects, flowering plants and
mammals, birds dominate Mega mammals mammals evolve Alps and Himalayas Form
Quaternary Period: (1.6 mya- today)
Mega mammals die out/ (Climate Change?) Present period Humans appear—100,000 years ago Grand Canyon forms Last ice age 15,000-10,000 years ago
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