Transcript Eras of Earth*s History

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
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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
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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
Comparison of the Dinosaurs
Triassic
Jurassic
Cretaceous
small
(Stegosaurus)
Med- large
T-rex, Triceraptops,
Raptors
Largest
Cold blooded
Warm blooded
Warm blooded
Reptile-like
More Advanced
Most Advanced/ Bird like
in many ways
Simple body plans
4 legs herbivores
2 legs carnivores
Defenses against
Preadtors
Most advanced features
Hollow bones (t rex,
raptors)
Proto-feathers on skin
Each continent had its
own unique Dinosaurs
*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