ELEVEN

EMERGENT PRECAMBRIAN 

(adapted from Lets Review Earth Science, 4th Ed., 2015); and

The Geologic Time Scale, 2012. 

Billion Years

Ago (BYA)

4.57

3.5

4.0

3.3

Earth consolidates into a massive molten sphere, under heavy meteroid bombardment

oceans present

oldest known rocks: Canada's Acasta Gneiss: 4030 mya

traces of inorganic oxygen (O2) release

oldest fossil-like objects (micro-fossils)

first anaerobic bacteria

3.2

photosynthetic bacteria

2.8

3.0

anaerobic prokaryotes diversify

oxygen from cyanobacteria  saturates oceans with iron oxide (Fe2O3)

H

A

D

E

A

N

EON

2.6

2.4

2.3

2.2

0.40

2.1

0.42

0.49

0.54

0.60

0.58

0.65

0.70

0.75

1.2

1.4

aerobic photosynthesis develops

A

R

C

H

A

E

N

2.5

P

R

O

T

E

R

O

Z

O

I

C

first widespread, diverse stromatolites

1.8

oxygen-rich atmosphere

oxygen enters atmosphere

eukaryotes develop - 2200 mya (2.2 bya)

oldest eukaryote fossil: Grypania spiralis

1.6

aerobic prokaryotes diversify

eukaryotes diversify

oldest traces of invertebrates

oldest large algae

megascopic eukaryotes develop & diversify

oldest body invertebrate fossils

ediacaran fauna: first multicellular, soft-bodied marine animals, and their diversity

extinction event

non-vascular land plants

early vascular plants

P

R

E

C

A

M

B

R

I

A

 

N

S

U

P

E

R

E

O

N

earliest trilobites - earliest arthropods

earliest fishes

C

A

M

B

R

I

A

N

Earth's oldest crustal material (detrital zircons)

formation of the solar system

end of global glaciation (deglaciation), CO2 drawdown, rise in oxygen

snowball Earth glaciation 

first appearance of metazoans

oldest macroscopic evidence of life

glaciations and rise in atmospheric oxygen

accretion of giant Moon-forming impact event

first stable proto-continents

rise in atmospheric oxygen

0.635

Great Oxygenation Event

Supercontinent Formation

Columbia

Late Archean Superevent

first appearance of global glaciation

850 mya

Cryogenian

635 mya

Ediacaran