Prehistory 1:

Geologic

Timeppt. by Robin D. Seamon

Resource: TEXTBOOK:

Prentice Hall Earth Science

notes

http://home.earthlink.net/~tran

qbase/images/fossils.jpg

HIGHLIGHTS:

• Earth: 4.5 billion years old

• ¾ of the geologic timeline holds life

• Life forms changed Earth’s chemistry

• Catastrophes affected the evolution of life-

extinctions

• New weedy species thrives & takes over after

an extinction

Geologic Time Scale

Geologic

Timeline in

Excel

LINK

EXTINCTIONS: widespread & rapid decreases in

amount of life on Earth.

5 major Extinctions:

65

myaK-Pg Extinction 75% extinct

(killed

dinosaurs)

Mammals &

birds survive

200

myaTriassic-Jurassic

extinction event75% extinct Dinos & birds

survive

251

myaPermian-Triassic

extinction event95% life extinct

“Great Dying”

Archosaurs

survive

375

myaDevonian

extinction70% extinct Marine life

changed

450

myaOrdovician-

Silurian extinction70% extinct X 2 2 events

Mass extinctions:

• Long-term stress compounded by short-term

shock (2 things)

POSSIBLE CAUSES

• Flood basalt events (LIP)

• Sea level falls

• Impact events (asteroid/comet)

• Sustained & significant global cooling

• Sustained & significant global warming

• Anoxic events: (lack of O in oceans-warming)

• Oceanic overturn (disruption of thermohaline

circulation)

• Plate tectonics

• Initiate/end Ice Ages

• Change ocean & wind patterns

• Close off or open land bridges

• Decrease continental shelf

• Arid interior

• OTHER:

• New disease

• Out-competition

• Man-made extinction of species

EFFECTS & RECOVERY

• Weedy species- species that can quickly adapt

to the environment; becomes dominate

• Reproduce quickly

• Disperse widely

• Live in a variety of habitats

• Establish populations in strange places

• Resist eradication once established

• 5-10 million years before re-diversification

Precambrian Era: Vast and Puzzling

4.5 Billion years ago to the Cambrian Period

3.4 bya: microscopic bacteria

Atmosphere: water vapor, CO2 , Nitrogen,

NO OXYGEN

Ozone layer protects from UV

Later, primary plants evolved, used

photosynthesis which created oxygen

Oxygen accumulates 2.5 bya

Precambrian Era: Vast and Puzzling

Fossils:

* stromatolites: layered mounds and columns of

calcium carbonate (material deposited by algae)

* chert: hard sedimentary rocks holding these

fossils

600 mya 1st multi-celled animals

EXTINCTION

Remnants of Precambrian Rocks

After Precambrian Era, time is divided into 3

other eras:

* Paleozoic Era

(Invertebrates Fish Amphibians)

* Mesozoic Era

* Cenozoic Era

Early Paleozoic Era: Life Evolves

540 mya

Divided into 6 time periods:

* Cambrian Period

* Ordovician Period

* Silurian Period

* Devonian Period

* Carboniferous Period

* Permian Period

Paleozoic Era

LIFE EVOLVES

early life began in the seas

shells, trilobites

Early Paleozoic Era: Life Evolves

Land masses:

* First: Gondwana ( S. Amer, Africa, Australia,

Antarctica, Asia) MAP

*Then another mass is raised: Laurasia

(N. Amer, Eurasia) MAP

* Then in Permian Period, there was: Pangea

(all continents together) MAP

ADVANCE

BACK

Cambrian Period: “Age of Invertebrates”

first organisms with shells, trilobites dominate

Ordovician Period: first fish

Silurian Period: “Age of Fishes”

first land plants

Devonian Period:

fish dominate, first insect fossils

Carboniferous Period: “Age of Amphibians”

amphibians abundant, large coal swamps,

Permian Period: extinction trilobites & other marine

animals; first reptiles

Periods of the Paleozoic Era

ppt LINK

ppt LINK

ppt LINK

Late Paleozoic Era

At the end of the Paleozoic Era, (400mya)

plants adapted to water’s edge to inland

Amphibians diversified

Greatest of 5 mass extinctions

(Climate became seasonal)

ADVANCE

Silurian Period

BACK

BACK

Ordovician Period

Armor-Plated Fish

BACK

Model of a Pennsylvanian

Coal Swamp

BACK

Permian Period Reptiles

ADVANCE

Mesozoic Era: “Age of Reptiles”

350 mya

Divided into 3 time periods:

* Triassic Period

* Jurassic Period

* Cretaceous Period

Dinosaurs were land-dwelling reptiles that

were dominate during Mesozoic Era

Major event: breakup of Pangea

Mesozoic Era: “Age of Reptiles”

Life:

* gymnosperms

* Canadian Rockies formed

* shelled egg: adaptation favoring land birth

IMPORTANT EVOLUTIONARY STEP

* Reptiles dominate

ADVANCE

BACK

The Flying Reptile Pteranodon

ADVANCE

Fossil Skull of an Extinct Crocodile

Periods of the Mesozoic Era

Triassic Period “Age of Reptiles”

Dinosaurs dominate

Jurassic Period

First birds, dinosaurs dominate

Cretaceous Period

First angiosperms (flowering plants)

ADVANCE

Jurassic Period

BACK

Cretaceous Period

MASS EXTINCTION!!!

K-Pg Boundary- Earth struck by 6-mile wide asteroid,

resulting in mass extinction: 65 mya

End of the Mesozoic Era:

Badlands, SD

Cenozoic Era: “Age of Mammals”

65 mya

Considered the “Age of Mammals”

Divided into two periods

* Tertiary Period

* Quaternary Period

Plate movement led to much mountain building,

volcanism, earthquakes

Cenozoic Era: “Age of Mammals”

Angiosperms replace gymnosperms as

dominate land plants

Mammals (animals that bear live young,

maintain steady body temperature) replace

reptiles as dominate animal

adaptations such as insulating body hair, more

efficient heart & lungs, allow mammals to lead

more active lives

Fossils from La Brea Tar Pits

Cenozoic Era: “Age of Mammals”

Life

Large mammals & extinction:

* In N. America, mastodon & mammoth

(huge relatives of elephant), saber-toothed cats,

giant beavers, large ground sloths, horses,

camels, giant bison become extinct

???? WHY???

Cenozoic Era: “Age of Mammals”

Mastadon

Wooly mammoth

Cenozoic Era: “Age of Mammals”

Saber-toothed tiger

Giant ground sloth

Cenozoic Era: Human Ancestors

2 mya – 10mya humans?

Reader’s Theater:

North American History

Character

LINK

Script

LINK

LAB:

Geologic Beaded

Timeline

LAB Activity:

Group Timeline Project

Precambrian Paleozoic Mesozoic Cenozoic

Cambrian

Your timeline should include in pictures and words the following: (use

color)

Time ( - )

Era _____________, “Age of _________” Period

Geology

Atmosphere & weather

*New adaptations

plants, animals

Extinctions?

COMPUTER LAB Activity:

Geologic Timeline in Excel

LINK

RESOURCE:

TEXTBOOK: Prentice Hall Earth Science

notes 6th grade