geological / evolutionary time

by Niel Brandt

Evolutionary Timeline

Time 

(Myr ago)

Event
4600
Formation of the approximately homogeneous solid Earth by planetesimal accretion 
4300
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
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
Bombardment of the Earth by planetesimals stops 
3800
The Earth's crust solidifies--formation of the oldest rocks found on Earth 
3800
Condensation of atmospheric water into oceans 
3500-2800
Prokaryotic cell organisms develop 
3500-2800
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
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
The Oklo natural fission reactor in Gabon goes into operation 
1600
The last reserves of reduced iron are used up by the increasing atmospheric oxygen--last banded iron formations 
1500
Eukaryotic cell organisms develop 
1500-600
Rise of multicellular organisms 
580-545
Fossils of Ediacaran organisms are made 
545
Cambrian explosion of hard-bodied organisms 
528-526
Fossilization of the Chengjiang site 
517-515
Fossilization of the Burgess Shale 
500-450
Rise of the fish--first vertebrates 
430
Waxy coated algae begin to live on land 
420
Millipedes have evolved--first land animals 
375
The Appalachian mountains are formed via a plate tectonic collision between North America, Africa, and Europe 
375
Appearance of primitive sharks 
350-300
Rise of the amphibians 
350
Primitive insects have evolved 
350
Primitive ferns evolve--first plants with roots 
300-200
Rise of the reptiles 
300
Winged insects have evolved 
280
Beetles and weevils have evolved 
250
Permian period mass extinction 
230
Roaches and termites have evolved 
225
Modern ferns have evolved 
225
Bees have evolved 
200
Pangaea starts to break apart 
200
Primitive crocodiles have evolved 
200
Appearance of mammals 
145
Archaeopteryx walks the Earth 
136
Primitive kangaroos have evolved 
100
Primitive cranes have evolved 
90
Modern sharks have evolved 
65
K-T Boundary--extinction of the dinosaurs and beginning of the reign of mammals 
60
Rats, mice, and squirrels have evolved 
60
Herons and storks have evolved 
55
Rabbits and hares have evolved 
50
Primitive monkeys have evolved 
28
Koalas have evolved 
20
Parrots and pigeons have evolved 
20-12
The chimpanzee and hominid lines evolve 
10-4
Ramapithecus exist 
4
Development of hominid bipedalism 
4-1
Australopithecus exist 
3.5
The Australopithecus Lucy walks the Earth 
2
Widespread use of stone tools 
2-0.01
Most recent ice age 
1.6-0.2
Homo erectus exist 
1-0.5
Homo erectus tames fire 
0.3
Geminga supernova explosion at a distance of roughly 60 pc--roughly as bright as the Moon
0.2-0.03
Homo sapiens neanderthalensis exist 
0.05-0
Homo sapiens sapiens exist 
0.04-0.012
Homo sapiens sapiens enter Australia from southeastern Asia and North America from northeastern Asia
0.025-0.01
Most recent glaciation--an ice sheet covers much of the northern United States 
0.02
Homo sapiens sapiens paint the Altamira Cave
0.012
Homo sapiens sapiens have domesticated dogs in Kirkuk, Iraq 
0.01
First permanent Homo sapiens sapiens settlements 
0.01
Homo sapiens sapiens learn to use fire to cast copper and harden pottery 
0.006
Writing is developed in Sumeria 

 

Top of page…

________________________________________

Geological Timeline


Table of geologic time 2004

The following table summarizes the major events and characteristics of the periods of time making up the geologic time scale. As above, this time scale is based on the International Commission on Stratigraphy.



free hit counter