Download - Life’s Timeline
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
