|
G
GEOLOGICAL PERIODS & EVENTS :
GEOLOGICAL
TIME DIVIDES INTO 4 MAJOR EONS:
FIRST
EON: ►HADEAN:
4.6 billion to 3.8 bya
no
evidence of fossil remains in rocks
dated
by meteorites & rocks collected during moon landings
 H
A D E A N
.----------.----------.----------.----------.----------.----------.----------.----------.----------.
4.5bya
3.5
2.5
1.5
0.5bya
[IN
THIS TIMELINE, EACH DASH IS
= 50 MILLION YEARS]
A R C H A E A N
.----------.----------.----------.----------.----------.----------.----------.----------.----------.
4.5bya
3.5
2.5
1.5
0.5bya
2ND
EON: ►ARCHAEAN
: 3.8 billion to 2.5 bya
heterotrophic & anaerobic bacteria dominate earth
chemosynthetic bacteria near ocean rifts
cyanobacteria start oxygen production & photosynthesis
2 –
2.5 bya
stromatolites & other mineral deposits by bacteria
sulfur
and iron used for energy
P
R O T E R O Z O I C
.----------.----------.----------.----------.----------.----------.----------.----------.----------.
4.5bya
3.5
2.5
1.5
0.5bya
3RD
EON ►PROTEROZOIC:
2.5 bya to 550 mya
bacterial to
eukaryotic life: internal membranes
allowed
formation of cell organelles
endosymbiosis
allowed: multiple chromosomes ,
mitochondria,
chloroplasts, flagellae, centrioles.
oxygen
allowed aerobic metabolism 2 bya
cell
cooperation & multicellularity led to
most
vertebrate &
invertebrate ancestors 800 mya
several lines
called Ediacara that disappeared
identity of
some fossils not clear: plant or fungi
first emergence
onto land 1.3 bya
PHANEROZOIC
.----------.----------.----------.----------.----------.----------.----------.----------.----------.
4.5bya
3.5
2.5
1.5
0.5bya
4th
EON ►PHANEROZOIC___________550
mya to present
eukaryotic
life expands
4th
EON ►PHANEROZOIC___________550
mya to present
eukaryotic
life expands
.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.
550mya 450mya
350mya 250mya
150mya 50mya
[IN
THE TIMELINE ABOVE, EACH DASH = 6.25 MILLION YEARS]
PHANEROZOIC EON IS DIVIDED INTO:
THREE
ERAS:
nPALEOZOIC:
550 million to 250 mya
nMESOZOIC:
250 million to 65 mya
nCENOZOIC:
65 mya to present
 
P A L
E O Z O I C
M E S O Z O I C
CENOZOIC
.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.
550mya
450mya 350mya
250mya 150mya
50mya
[EACH
RED ARROW IS AN EXTINCTION EVENT]
nPALEOZOIC
ERA IS DIVIDED INTO:
SIX
PERIODS:
CAMBRIAN most
phyla present; earliest chordate fossils; few land
dwelling
organisms; trilobites dominate; exoskeletons
and compound
eyes;
ORDOVICIAN algae
invade land; first land plants; early fish
large deposits
of calcium carbonate = today’s marble;
extinction
event;
SILURIAN ferns
& nonvascular plants; early insects;
first jawed
fish; abundant eurypterids & crinoids
brachiopods =
80% of shelled species;
nPALEOZOIC
ERA CONTINUED
DEVONIAN fusiline
foraminifera;
fish expand ;
shouldered fish & crossopterygians;
tetrapods
develop; amphibians appear & 1st reptiles;
first insects;
forests expand from ferns
CARBONIFEROUS large forests
of ferns & gymnosperms; extensive
coal swamps;
echinoderms very abundant;
amphibians &
reptiles reach large sizes;
first winged insects
PERMIAN
conifers beginning to replace fern forests; dimetrodon;
first ray
finned fish;
large scale
volcanic action ; worldwide glaciation;
largest extinction
event at end;
THE
PALEOZOIC ERA ENDED WITH A LARGE
EXTINCTION EVENT
 .--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.
550mya 450mya 350mya
250mya 150mya 50mya
PERMIAN
EXTINCTION
EVENT
 
P A L E O Z O I
C M E S O Z O
I C CENOZOIC
.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.
550mya
450mya 350mya
250mya 150mya
50mya
nMESOZOIC
ERA IS DIVIDED INTO:
THREE
PERIODS:
TRIASSIC
early dinosaurs; first hexacorallia; most crinoids extinct;
marine reptiles
like ichthyosaurus & pleisiosaurus;
flowering
plants first appear;
JURASSIC marine
diatoms appear; fern & conifer forests dominate;
dinosaurs
expand to large sauropods & theropods
birds appear;
flowering plants expand.
CRETACEOUS conifer
forests dominate land; coal beds laid down
extinction
event; first mammals present
THE
MESOZOIC ERA ENDED WITH A LARGE
EXTINCTION EVENT
CENOZOIC
.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.
550mya 450mya 350mya
250mya 150mya 50mya
PERMIAN DINOSAUR
EXTINCTION
EVENT EXTINCTION
 nCENOZOIC
ERA: THE MODERN ERA
   .--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.
550mya 450mya 350mya
250mya 150mya
[1 DASH = 6.25 MILLION YEARS]
DINOSAUR
EXTINCTION
DINOSAUR
HUMAN
EXTINCTION
ANCESTORS
 
.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.----.-.
70 60 50
40 30 20 10
[IN
THE CENOZOIC TIMELINE, 1 DASH = 1 MILLION YEARS]
nCENOZOIC
ERA IS DIVIDED INTO:
TWO
PERIODS:
TERTIARY PERIOD : 65
million to 1.8 mya
Mammals become
dominant vertebrate on land
QUATERNARY PERIOD: 1.8 mya to present
Megafauna such
as wooly mammoth, wooly rhinoceros,
& giant
ground sloth .
Humans expand
to 7 billion
FULL TIME LINE
(ONE DASH =50Ma)
.----------.----------.----------.----------.----------.----------.----------.----------.----------.
4.5bya 3.5
2.5 1.5
0.5bya
PHANEROZOIC EON TIME LINE(ONE
DASH = 6.25 Ma)
.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.--------.
550mya 450mya 350mya
250mya 150mya 50mya
PERMIAN DINOSAUR
EXTINCTION EVENT EXTINCTION
CENOZOIC ERA TIME LINE
DINOSAUR
HUMAN
EXTINCTION
ANCESTORS
-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.-----.
70 60 50 40 30
20 10
[IN
THE TIMELINE ABOVE, EACH DASH IS 1 MILLION YEARS]
|