Life’s TimelineLife’s

Timeline

Earth is

Born

aka The

Precambrian

Era

The First 100 million years

• Cosmic junk hits • Giant collisions melt

the planet• Density stratification

The First AtmosphereThe First Atmosphere

– Hydrogen cyanide– Carbon Dioxide– Carbon Monoxide– Nitrogen– Hydrogen Sulfite– Water

– Hydrogen cyanide– Carbon Dioxide– Carbon Monoxide– Nitrogen– Hydrogen Sulfite– Water

• TOXIC!!!• TOXIC!!!

4 b.y.a.

• 1st solid rocks• Lots of volcanos• Cosmic junk bombards surface

• Too hot for liquid H2O!

• 1st solid rocks• Lots of volcanos• Cosmic junk bombards surface

• Too hot for liquid H2O!

3.8 b.y.a.3.8 b.y.a.

• Cool enough for liquid water• Storms cover Earth in water• Oceans form• Lots of dissolved iron in oceans

• Cool enough for liquid water• Storms cover Earth in water• Oceans form• Lots of dissolved iron in oceans

3.6 – 3.5 b.y.a.3.6 – 3.5 b.y.a.

• Bacteria-like life forms common in oceans – Evidence: microfossils!

• Bacteria-like life forms common in oceans – Evidence: microfossils!

2.2 b.y.a.2.2 b.y.a.

• Photosynthetic bacteria producing Oxygen– Oxygen + Iron in oceans = RUST

appears!– Rust falls to ocean floor = oceans turn

blue-green– Oxygen builds up in atmosphere…

• Photosynthetic bacteria producing Oxygen– Oxygen + Iron in oceans = RUST

appears!– Rust falls to ocean floor = oceans turn

blue-green– Oxygen builds up in atmosphere…

Atmospheric O2 Accumulates

Atmospheric O2 Accumulates

• Ozone forms protective layer! • Sky turns blue!• Cells DIE OR MOVE to oxygen-free

habitats (Their descendants are still there!)

• New cells use oxygen!

• Ozone forms protective layer! • Sky turns blue!• Cells DIE OR MOVE to oxygen-free

habitats (Their descendants are still there!)

• New cells use oxygen!

• Prokaryotic cells evolve interior membranes e.g. nuclei!!!

• Endosymbiosis leads to Eukaryotic cells with– Mitochondria– chloroplasts

• Prokaryotic cells evolve interior membranes e.g. nuclei!!!

• Endosymbiosis leads to Eukaryotic cells with– Mitochondria– chloroplasts

2 b.y.o2 b.y.o

• Eukaryotic cells continue to evolve Sexual Reproduction!!!– Evolution SPEEDS UP!!!, as sexual

reproduction allows allele shuffling so that offspring are not identical to their parents.

• Eukaryotic cells continue to evolve Sexual Reproduction!!!– Evolution SPEEDS UP!!!, as sexual

reproduction allows allele shuffling so that offspring are not identical to their parents.

Later…Later…

A few hundred-million years later…

A few hundred-million years later…

• Evolution of MULTICELLULAR ORGANISMS!!!

• Evolution of MULTICELLULAR ORGANISMS!!!

Earth as a ToddlerEarth as a Toddler

The Paleozoic EraThe Paleozoic Era

The Cambrian Period: 544-505 m.y.a.

The Cambrian Period: 544-505 m.y.a.

• Diversification• Firsts:

– Tough body parts (outer skeletons, shells)– Animals

•Invertebrates: jelly fish, worm, sponge•Brachiopods: (2 shells) Trilobites

• Diversification• Firsts:

– Tough body parts (outer skeletons, shells)– Animals

•Invertebrates: jelly fish, worm, sponge•Brachiopods: (2 shells) Trilobites

The Ordovician and Silurian Periods:505-410 m.y.a.

The Ordovician and Silurian Periods:505-410 m.y.a.

• Firsts:– Backbones!!! first vertebrates: jawless

fishes– Insects! (invertebrates)– Land Plants! (low to ground in damp areas)

• Firsts:– Backbones!!! first vertebrates: jawless

fishes– Insects! (invertebrates)– Land Plants! (low to ground in damp areas)

The Devonian Period:410-363 m.y.a.

The Devonian Period:410-363 m.y.a.

– Ferns and dry-land plants– SHARKS!!!

• jaws, bones, and scales

– LAND ANIMALS!•1st AMPHIBIANS!!!

– Ferns and dry-land plants– SHARKS!!!

• jaws, bones, and scales

– LAND ANIMALS!•1st AMPHIBIANS!!!

The Carboniferous and Permian Periods:363-245 m.y.a.

The Carboniferous and Permian Periods:363-245 m.y.a.

– REPTILES!!!– Huge Winged Insects!– Vast Forests! (giant ferns)

– REPTILES!!!– Huge Winged Insects!– Vast Forests! (giant ferns)

The PermianMASS EXTINCTION:

End of the Paleozoic

The PermianMASS EXTINCTION:

End of the Paleozoic

• Extinct:– 95% of ocean life– Many amphibians, land animals and

plants

• Survivors: some fish and reptiles…

• Extinct:– 95% of ocean life– Many amphibians, land animals and

plants

• Survivors: some fish and reptiles…

The Mesozoic EraThe Mesozoic Era

Age of the ReptilesAge of the Reptiles

The Triassic Period:245-208 m.y.a.

The Triassic Period:245-208 m.y.a.

• Mass Extinction of – fishes, insects, reptiles, cone-bearing

plants

• DINOSAURS!!! (225 m.y.a.)

• MAMMALS! (late Triassic)• Evolved from reptiles• Very small

• Mass Extinction of – fishes, insects, reptiles, cone-bearing

plants

• DINOSAURS!!! (225 m.y.a.)

• MAMMALS! (late Triassic)• Evolved from reptiles• Very small

The Jurassic Period:208-145 m.y.a.

The Jurassic Period:208-145 m.y.a.

• Dominant Players: Dinosaurs (on land)

• BIRDS!!!– Archaeopteryx

• Evolved from dinosaurs

• Dominant Players: Dinosaurs (on land)

• BIRDS!!!– Archaeopteryx

• Evolved from dinosaurs

The Cretaceous Period:145-65 m.y.a.

The Cretaceous Period:145-65 m.y.a.

– Land: Dinosaurs (T. rex) – Air: Birds, Flying Dinosaurs– Water: Turtles, Crocodiles, Dinosaurs,

Fish, Invertebrates

• Firsts:– Leafy Trees, FLOWERS!!! (fruits)

– Land: Dinosaurs (T. rex) – Air: Birds, Flying Dinosaurs– Water: Turtles, Crocodiles, Dinosaurs,

Fish, Invertebrates

• Firsts:– Leafy Trees, FLOWERS!!! (fruits)

The MesozoicMASS EXTINCTION

The MesozoicMASS EXTINCTION

– Over 50% of all plants and animals– All Dinosaurs

– Over 50% of all plants and animals– All Dinosaurs

The Cenozoic EraThe Cenozoic Era

The Age of MammalsThe Age of Mammals

The Tertiary Period:65-1.8 m.y.a.

The Tertiary Period:65-1.8 m.y.a.

• Warm, mild climate

– Whales, Dolphins– Grazing mammals– The earliest Human Ancestor (3.5

m.y.a.)

• Warm, mild climate

– Whales, Dolphins– Grazing mammals– The earliest Human Ancestor (3.5

m.y.a.)

The Quaternary Period:1.8 m.y.a. - Present

The Quaternary Period:1.8 m.y.a. - Present

• ICE AGES– oceans falls 100m– 20 k.y.a. – warms up – oceans rise again

• Firsts: HUMANS (~150 k.y.a.)

• ICE AGES– oceans falls 100m– 20 k.y.a. – warms up – oceans rise again

• Firsts: HUMANS (~150 k.y.a.)

Life’s Timeline

Life’s Timeline