the history of life

Foothill High School Science Department

The History of Life

Evolution of Multicellular Life


The Fossil Record

• DocumentsDocuments– Evolutionary HistoriesEvolutionary Histories– ClimateClimate– GeographyGeography– Life FormsLife Forms


Precambrian Time

• Covers 90% of Earths HistoryCovers 90% of Earths History• During This Period:During This Period:– Simple Anaerobic Life FormedSimple Anaerobic Life Formed– Then Photosynthetic OrganismsThen Photosynthetic Organisms• Released OxygenReleased Oxygen

– Aerobic Life FormedAerobic Life Formed– Eukaryotes DevelopedEukaryotes Developed– Multicellular Organisms AppearedMulticellular Organisms Appeared

Start

Finish


Cambrian Period

• Cambrian ExplosionCambrian Explosion–Huge Numbers of Multicellular Life Forms Huge Numbers of Multicellular Life Forms

DevelopedDeveloped– Shells, Outer Skeletons, AppearedShells, Outer Skeletons, Appeared– Trilobites, Brachiopods, Invertebrates Trilobites, Brachiopods, Invertebrates

ArrivedArrived– Burgess Shale in British Columbia is a Burgess Shale in British Columbia is a

famous fossil site for this eventfamous fossil site for this event


Paleozoic Era

Key ConceptKey Concept::Early In The Paleozoic Era, Early In The Paleozoic Era,

The Fossil Record Became The Fossil Record Became Rich With Evidence of Rich With Evidence of Many Types of Marine Many Types of Marine LifeLife

Paleozoic WeblinkPaleozoic WeblinkAge of the Trilobites


Ordovician & Silurian Periods

• First Appearance of:First Appearance of:– Octopus, SquidOctopus, Squid– Aquatic ArthropodsAquatic Arthropods– VertebrateVertebrate• Jawless Fishes (suckers)Jawless Fishes (suckers)

– InsectsInsects– PlantsPlants


Devonian Period

Ferns Appear

Fish Proliferate

Sharks Appear

Amphibians Evolve


Devonian Period

Key ConceptKey Concept::

During The Devonian, Animals During The Devonian, Animals Began To InvadeBegan To Invade

LandLand


Carboniferous & Permian Periods

• Life Expands Across The Continents–Reptiles–Winged Insects• Dragonflies, Cockroaches

–Giant Ferns, Swampy Forests• Laid Down Coal Deposits


Carboniferous & Permian Periods

Key ConceptKey Concept::The Mass Extinction At The End Of The The Mass Extinction At The End Of The

Paleozoic Affected Both Plants & Paleozoic Affected Both Plants & Animals On Land & In The Seas. 95% Animals On Land & In The Seas. 95% Of Complex Ocean Life Forms Of Complex Ocean Life Forms Disappears Disappears


Permian Extinction

• Killed OffKilled Off–TrilobitesTrilobites–Many AmphibiansMany Amphibians

• What SurvivedWhat Survived–Most FishesMost Fishes–Numerous ReptilesNumerous Reptiles

Extinction

ExtinctionLinkLink


Mesozoic EraKey ConceptKey Concept::

Events During The 180 Million Years Of The Events During The 180 Million Years Of The Mesozoic Era Include The Increasing Dominance Mesozoic Era Include The Increasing Dominance Of Dinosaurs. The Mesozoic Is Marked By The Of Dinosaurs. The Mesozoic Is Marked By The Appearance Of Flowering PlantsAppearance Of Flowering Plants


Mesozoic Era


Triassic Period

• Made Up Of The Made Up Of The Organisms That Survived Organisms That Survived The Permian ExtinctionThe Permian Extinction

• Cone Bearing Plants Cone Bearing Plants AppearAppear

• ““AGE of REPTILESAGE of REPTILES””


Triassic Period

• Mammals Appear In The Late Mammals Appear In The Late TriassicTriassic–Small Shrewlike OrganismsSmall Shrewlike Organisms


Jurassic Period

Dinosaurs Still RuleDinosaurs Still RuleFirst Birds AppearFirst Birds AppearArchaeopteryxArchaeopteryx


Cretaceous Period• Dinosaurs Still DominantDinosaurs Still Dominant– T. rexT. rex

• Flying ReptilesFlying Reptiles– Became Extinct During CretaceousBecame Extinct During Cretaceous

• Seas ContainedSeas Contained– TurtlesTurtles– CrocodilesCrocodiles– PlesiosaursPlesiosaurs


Cretaceous

• Appearance of:Appearance of:–Leafy TreesLeafy Trees–ShrubsShrubs–Small Flowering PlantsSmall Flowering Plants• True SeedsTrue Seeds• Often Enclosed In FruitOften Enclosed In Fruit


Cretaceous Extinction• 65 Million Years Ago65 Million Years Ago• > 50% of All Plant & Animal Groups Wiped Out> 50% of All Plant & Animal Groups Wiped Out– Including ALL the DinosaursIncluding ALL the Dinosaurs


Cenozoic Era

The Age of MammalsThe Age of MammalsKey Concept:Key Concept:

During The Cenozoic, Mammals Evolved During The Cenozoic, Mammals Evolved Adaptations That Allowed Them To Live In Adaptations That Allowed Them To Live In Various Environments – On Land, Water & Air.Various Environments – On Land, Water & Air.


Tertiary Period

• Climates Warm & MildClimates Warm & Mild• Whales & Dolphins EvolveWhales & Dolphins Evolve• Grasses EvolveGrasses Evolve– Grazing Mammals EvolvedGrazing Mammals Evolved

• Some Mammals & Birds Became Very LargeSome Mammals & Birds Became Very Large


Tertiary Mammals


Quaternary Period

• Climate CooledClimate Cooled– Several Ice Ages OccurredSeveral Ice Ages Occurred• Sea Levels Dropped By Over 100 Meters (300 Sea Levels Dropped By Over 100 Meters (300

Feet)Feet)

• 20,000 Years Ago20,000 Years Ago– Climate WarmedClimate Warmed– Ice Packs MeltedIce Packs Melted– Sea Level ReturnedSea Level Returned


Ice Age


Quaternary Period

• 4.5 Million Years Ago4.5 Million Years Ago– Our Primate Ancestors Our Primate Ancestors

EvolvedEvolved• 100,000 Years Ago100,000 Years Ago– Genus Homo Arose In Genus Homo Arose In

AfricaAfrica• Migrated Across The World Migrated Across The World

In A Series of MigrationsIn A Series of Migrations

the history of life

Documents

eventpaleozoic erakey

permian extinctioncone

years agogenus homo

complex ocean life forms

plants animals

famous fossil site

swampy forestslaid

water air