Time (years before present)
|
Events |
| 4550 million |
Formation of the approximately homogeneous solid Earth
by planetesimal accretion |
| 4300 million |
Melting of the Earth due to radioactive and
gravitational heating which leads to its differentiated interior structure
as well as outgassing of molecules such as water, methane, ammonia,
hydrogen, nitrogen, and carbon dioxide |
| 4300 million |
Atmospheric water is photodissociated by ultraviolet
light to give oxygen atoms which are incorporated into an ozone layer and
hydrogen molecules which escape into space |
| 4000 million |
Bombardment of the Earth by planetesimals stops |
| 3800 million |
The Earth's crust solidifies--formation of the oldest
rocks found on Earth |
| 3800 million |
Condensation of atmospheric water into oceans |
| 3500-2800 million |
Prokaryotic cell organisms develop |
| 3500-2800 million |
Beginning of photosynthesis by blue-green algae which
releases oxygen molecules into the atmosphere and steadily works to
strengthen the ozone layer and change the Earth's chemically reducing
atmosphere into a chemically oxidizing one |
| 2400 million |
Rise in the concentration of oxygen molecules stops
the deposition of uraninites (since they are soluble when combined with
oxygen) and starts the deposition of banded iron formations |
| 2000 million |
The Oklo natural fission reactor in Gabon goes into
operation |
| 1600 million |
The last reserves of reduced iron are used up by the
increasing atmospheric oxygen--last banded iron formations |
| 1500 million |
Eukaryotic cell organisms develop |
| 1500-600 million |
Rise of multicellular organisms |
| 580-545 million |
Fossils of Ediacaran organisms are made |
| 545 million |
Cambrian explosion of hard-bodied organisms |
| 528-526 million |
Fossilization of the Chengjiang site |
| 517-515 million |
Fossilization of the Burgess Shale |
| 500-450 million |
Rise of fish, the first vertebrates |
| 430 million |
Waxy coated algae begin to live on land |
| 420 million |
Millipedes have evolved, the first land animals |
| 375 million |
The Appalachian mountains are formed via a plate
tectonic collision between North America, Africa, and Europe |
| 375 million |
Appearance of primitive sharks |
| 350-300 million |
Rise of the amphibians |
| 350 million |
Primitive insects have evolved |
| 350 million |
Primitive ferns evolve, the first plants with roots |
| 300-200 million |
Rise of reptiles |
| 300 million |
Winged insects have evolved |
| 280 million |
Beetles and weevils have evolved |
| 250 million |
Permian period mass extinction of more than 90% living species |
| 23 million |
Roaches and termites have evolved |
| 225 million |
Modern ferns have evolved |
| 225 million |
Bees have evolved |
| 200 million |
Pangaea single continent starts to break apart |
| 200 million |
Primitive crocodiles have evolved |
| 200 million |
Appearance of mammals |
| 145 million |
Archaeopteryx walks the Earth |
| 136 million |
Primitive kangaroos have evolved |
| 100 million |
Primitive cranes have evolved |
| 90 million |
Modern sharks have evolved |
| 65 million |
K-T Boundary: extinction of the dinosaurs and
beginning of the reign of mammals |
| 60 million |
Rats, mice, and squirrels have evolved |
| 60 million |
Herons and storks have evolved |
| 55 million |
Rabbits and hares have evolved |
| 50 million |
Primitive monkeys have evolved |
| 28 million |
Koalas have evolved |
| 20 million |
Parrots and pigeons have evolved |
| 20-12 million |
The chimpanzee and hominid lines evolve |
| 10-4 million |
Ramapithecus exists (anthropological evidence, fossils) |
| 4 million |
Development of hominid bipedalism |
| 4-1 million |
Australopithecus exists (anthropological evidence, fossils) |
| 3.5 million |
The Australopithecus Lucy walks the Earth
|
| 2 million |
Widespread use of stone tools |
| 2000000-10000 |
Most recent ice age |
| 1.6-0.2 million |
Homo erectus exists (anthropological evidence, fossils) |
| 1-0.5 million |
Homo erectus tames fire |
| 0.3 million |
Geminga supernova explosion at a distance of roughly
60 pc--roughly as bright as the Moon |
| 200000-30000 |
Homo sapiens neanderthalensis exists (anthropological evidence, fossils) |
| <150000 |
Homo sapiens sapiens exists (anthropological evidence, fossils) |
| 80000-10000 |
Homo sapiens sapiens enter Australia from
southeastern Asia and North America from northeastern Asia |
| 25000-10000 |
Most recent glaciation--an ice sheet covers much of
the northern United States |
| 20000 |
Homo sapiens sapiens paint the Altamira
Cave |
| 12000 |
Homo sapiens sapiens domesticate dogs in
Kirkuk, Iraq |
| 10000 |
First permanent Homo sapiens sapiens
settlements |
| 10000 |
Homo sapiens sapiens learn to use fire to cast
copper and harden pottery |
| 6000 |
Writing is developed in Sumeria |