Million Years Ago
Physical Event
Life Event
4570
Formation of Earth
No life yet.
4500
Planetary Collision forms Moon
~4450
Atmosphere Forms (Red)
Composition: poisonous volcanic
gasses, No Oxygen in the air!
Intense lightning and UV radiation (no ozone
layer yet) may have provided the energy
necessary to form first cells.
4400
Earth’s Crust Forms
4300
Oceans Form (Green from the Iron)
4280
Oldest existing Crust
(Hudson Bay Canada)
Earth is Now 1 Billion Years Old!
Oldest Fossils (Australia)
Cyanobacteria add Oxygen to the
ocean.
Oxygen bonds to iron and turns
ocean from GREEN to BLUE
The ocean becomes saturated with
oxygen, so excess oxygen diffuses into
the air and turns the sky from red to
blue.
First evidence of life!
Simple, Single Celled life
3500
2700
2400
2200
Oldest Fossils of Complex Cells
(kingdom protista)
1200
Red & Brown Algae
600
Earth is Now 4 Billion Years Old!
550
Oxygen levels increasing from
Photosynthesis; may have promoted
the Cambrian Explosion of life.
500
Macroevolution: Evolution of oxygenreleasing photosynthesis in Cyanobacteria.
Mass extinction caused by the toxic oxygen.
“Oxygen holocaust”
Macroevolution: Life takes a big step towards
complexity. Eukaryotes evolve through
endosymbiosis.
Macroevolution:
Evolution of multi-celled life
Evolution of simple algae & aquatic animals
(all soft bodied)
(Cambrian Explosion) Sudden increase in
types of animals.
Body Plans evolving:
 Irregular, Radial, Bilateral
Origin of all major phyla (types) of animals
that we have today.
First Vertebrates (Jawless-Fish)
475
Ozone Layer has formed
475
Plants Colonize Land and soil begins
to form from organic buildup
Protection from UV radiation allows evolution
of life on land!
Evolution of land plants:
Benefit – more light exposure
Problems- dehydration
460
Organic matter is recycled which
helps soil to form
455
Evolution of Fungus (decomposer)
First shark fossils
450
(Arthropods have exoskeletons, and
jointed appendages e.g. crabs,
lobsters)
Crab-like animals colonize land.
440
Climate Cools: Massive Glaciers
Mass Extinction
Ordovician Extinction
423
400
Evolution of Vascular Plants
(Insects are also arthropods)
Evolution of Insects
395
Evolution of Tetrapods (four limbs)
385
Evolution of Seed Plants
370
Vertebrates Colonize Land
360
Mass Extinction 70% of Marine Species
360
Evolution of Amphibians
300
Evolution of Reptiles
251
230
Pangaea Forms:
Mass Extinction (Major) 96%/70%
“Permian Extinction”
 Disrupts global climate
Took about 20 million years for
Evolution of dinosaurs
dinosaurs to evolve after the Earth was
 Adaptive Radiation of dinosaurs
‘emptied’
210
Mass Extinction (70% ?)
200
Evolution of Mammals
Evolution of cone-bearing plants
150
Evolution of Birds
130
Evolution of Flowers
65
Two major hypotheses:
 Meteor
 Volcanos & Tectonics & Climate
Change
Mass Extinction 50%
50% of all aquatic and terrestrial species
disappear from fossil record.
Loss of Dinosaurs opened up new niches for
Mammals. Mammals began a long period of
“Adaptive Radiation”
60
Evolution of Primates (have tails)
20
Evolution of Great Apes (no tail)