Eon |
Era |
Period[2] |
Series/
Epoch |
Major Events |
Start, Million
Years Ago[3] |
Phane-
rozoic |
Cenozoic |
Neogene[4] |
Holocene |
End of
recent glaciation and rise of modern
civilization. |
0.011430
± 0.00013[5] |
Pleistocene |
Flourishing and then extinction of
many large
mammals (Pleistocene
megafauna). Evolution of anatomically modern
humans. |
1.806 ±
0.005 * |
Pliocene |
Intensification of present
ice age; cool and dry
climate.
Australopithecines, many of the existing genera of
mammals, and recent
mollusks appear.
Homo habilis appears. |
5.332 ±
0.005 * |
Miocene |
Moderate climate;
Orogeny in
northern hemisphere. Modern
mammal and
bird families became recognizable.
Horses and
mastodons diverse.
Grasses become ubiquitous. First
apes
appear. |
23.03 ±
0.05 * |
Paleogene
[4] |
Oligocene |
Warm climate; Rapid
evolution and diversification of fauna, especially
mammals. Major evolution and dispersal of modern types
of
flowering plants |
33.9±0.1
* |
Eocene |
Archaic
mammals (e.g.
Creodonts,
Condylarths,
Uintatheres, etc) flourish and continue to develop
during the epoch. Appearance of several "modern" mammal
families. Primitive
whales diversify. First
grasses. Reglaciation of
Antarctica; current ice age begins. |
55.8±0.2
* |
Paleocene |
Climate tropical. Modern
plants appear;
Mammals diversify into a number of primitive lineages
following the
extinction of the dinosaurs. First large mammals (up to
bear or small hippo size). |
65.5±0.3
* |
Mesozoic |
Cretaceous |
Upper/Late |
Flowering plants proliferate, along with new types of
insects. More modern
teleost fish begin to appear.
Ammonites,
belemnites,
rudist
bivalves,
echinoids and
sponges all common. Many new types of
dinosaurs (e.g.
Tyrannosaurs,
Titanosaurs,
duck bills, and
horned dinosaurs) evolve on land, as do
modern crocodilians; and
mosasaurs and modern sharks appear in the sea. Primitive
birds gradually replace pterosaurs.
Monotremes,
marsupials and
placental mammals appear. Break up of
Gondwana. |
99.6±0.9
* |
Lower/Early |
145.5 ±
4.0 |
Jurassic |
Upper/Late |
Gymnosperms (especially
conifers,
Bennettitales and
cycads) and
ferns common. Many types of
dinosaurs, such as
sauropods,
carnosaurs, and
stegosaurs. Mammals common but small. First
birds and
lizards.
Ichthyosaurs and
plesiosaurs diverse.
Bivalves,
Ammonites and
belemnites abundant.
Sea urchins very common, along with
crinoids, starfish,
sponges, and
terebratulid and
rhynchonellid
brachiopods. Breakup of
Pangea into
Gondwana and
Laurasia. |
161.2 ±
4.0 |
Middle |
175.6 ±
2.0 * |
Lower/Early |
199.6 ±
0.6 |
Triassic |
Upper/Late |
Archosaurs dominant on land as
dinosaurs, in the oceans as
Ichthyosaurs and
nothosaurs, and in the air as
pterosaurs.
cynodonts become smaller and more mammal-like, while
first
mammals and
crocodilia appear.
Dicrodium flora common on land. Many large aquatic
temnospondyl amphibians.
Ceratitic ammonoids extremely common.
Modern corals and
teleost fish appear, as do many modern
insect clades. |
228.0 ±
2.0 |
Middle |
245.0 ±
1.5 |
Lower/Early |
251.0 ±
0.4 * |
Paleozoic |
Permian |
Lopingian |
Landmasses unite into
supercontinent
Pangea, creating the
Appalachians. End of Permo-Carboniferous glaciation.
Synapsid
reptiles (pelycosaurs
and
therapsids) become plentiful, while
parareptiles and
temnospondyl
amphibians remain common. In the mid-Permian,
coal-age flora are replaced by
cone-bearing
gymnosperms (the first true
seed plants) and by the first true
mosses.
Beetles and
flies evolve. Marine life flourishes in warm shallow
reefs;
productid and
spiriferid brachiopods, bivalves,
forams, and
ammonoids all abundant.
Permian-Triassic extinction event occurs 251 mya: 95
percent of life on Earth becomes extinct, including all
trilobites,
graptolites, and
blastoids. |
260.4 ±
0.7 * |
Guadalupian |
270.6 ±
0.7 * |
Cisuralian |
299.0 ±
0.8 * |
Carbon-
iferous[6]/
Pennsyl-
vanian |
Upper/Late |
Winged insects radiate suddenly; some (esp.
Protodonata and
Palaeodictyoptera) are quite large.
Amphibians common and diverse. First
reptiles and
coal forests (scale
trees, ferns,
club trees,
giant horsetails,
Cordaites, etc.). Highest-ever
oxygen levels.
Goniatites, brachiopods, bryozoa, bivalves, and corals
plentiful in the seas. Testate
forams proliferate. |
306.5 ±
1.0 |
Middle |
311.7 ±
1.1 |
Lower/Early |
318.1 ±
1.3 * |
Carbon-
iferous[6]/
Missis-
sippian |
Upper/Late |
Large
primitive trees, first
land vertebrates, and amphibious
sea-scorpions live amid
coal-forming coastal
swamps. Lobe-finned
rhizodonts are big fresh-water predators. In the oceans,
early
sharks are common and quite diverse;
echinoderms (esp.
crinoids and
blastoids) abundant.
Corals,
bryozoa,
goniatites and brachiopods (Productida,
Spiriferida, etc.) very common. But
trilobites and
nautiloids decline.
Glaciation in East
Gondwana. |
326.4 ±
1.6 |
Middle |
345.3 ±
2.1 |
Lower/Early |
359.2 ±
2.5 * |
Devonian |
Upper/Late |
First
clubmosses,
horsetails and
ferns appear, as do the first
seed-bearing plants (progymnosperms),
first
trees (the tree-fern
Archaeopteris), and first (wingless)
insects.
Strophomenid and
atrypid
brachiopods,
rugose and
tabulate corals, and
crinoids are all abundant in the oceans.
Goniatite
ammonoids are plentiful, while squid-like
coleoids arise. Trilobites and armoured agnaths decline,
while jawed fishes (placoderms,
lobe-finned and
ray-finned fish, and early
sharks) rule the seas. First
amphibians still aquatic. "Old Red Continent" of
Euramerica. |
385.3 ±
2.6 * |
Middle |
397.5 ±
2.7 * |
Lower/Early |
416.0 ±
2.8 * |
Silurian |
Pridoli |
First
vascular
plants (the
whisk ferns and their relatives), first
millipedes and
arthropleurids on land. First jawed
fishes, as well as many
armoured
jawless fish, populate the seas.
Sea-scorpions reach large size.
Tabulate and
rugose corals,
brachiopods (Pentamerida,
Rhynchonellida, etc.), and
crinoids all abundant.
Trilobites and
mollusks diverse;
graptolites not as varied. |
418.7 ±
2.7 * |
Upper/Late (Ludlow) |
422.9 ±
2.5 * |
Wenlock |
428.2 ±
2.3 * |
Lower/Early (Llandovery) |
443.7 ±
1.5 * |
Ordovician |
Upper/Late |
Invertebrates diversify into many new types (e.g., long
straight-shelled
cephalopods). Early
corals, articulate
brachiopods (Orthida, Strophomenida,
etc.),
bivalves,
nautiloids,
trilobites,
ostracods,
bryozoa, many types of
echinoderms (crinoids,
cystoids,
starfish, etc.), branched
graptolites, and other taxa all common.
Conodonts (early
planktonic
vertebrates) appear. First
green plants and
fungi on land. Ice age at end of period. |
460.9 ±
1.6 * |
Middle |
471.8 ±
1.6 |
Lower/Early |
488.3 ±
1.7 * |
Cambrian |
Upper/Late (Furongian) |
Major diversification of
life in the
Cambrian Explosion. Many fossils; most modern
animal
phyla appear. First
chordates appear, along with a number of extinct,
problematic phyla. Reef-building
Archaeocyatha abundant; then vanish.
Trilobites,
priapulid worms,
sponges, inarticulate
brachiopods (unhinged lampshells), and many other
animals numerous.
Anomalocarids are giant predators, while many Ediacaran
fauna die out.
Prokaryotes,
protists (e.g.,
forams),
fungi and
algae continue to present day.
Gondwana emerges. |
501.0 ±
2.0 * |
Middle |
513.0 ±
2.0 |
Lower/Early |
542.0 ±
0.3 * |
Proter-
ozoic
[7] |
Neo-
proterozoic |
Ediacaran |
Good
fossils of
multi-celled animals. Ediacaran fauna (or
Vendobionta) flourish worldwide in seas.
Trace fossils of worm-like Trichophycus, etc.
First
sponges and
trilobitomorphs. Enigmatic forms include oval-shaped
Dickinsonia, frond-shaped
Charniodiscus, and many soft-jellied creatures. |
630
+5/-30 * |
Cryogenian |
Possible "snowball
Earth" period.
Fossils still rare.
Rodinia landmass begins to break up. |
850
[8] |
Tonian |
Rodinia supercontinent persists.
Trace fossils of simple
multi-celled
eukaryotes. First radiation of
dinoflagellate-like
acritarchs. |
1000
[8] |
Meso-
proterozoic |
Stenian |
Narrow highly
metamorphic belts due to
orogeny as supercontinent
Rodinia is formed. |
1200
[8] |
Ectasian |
Platform covers continue to expand.
Green algae
colonies in the seas. |
1400
[8] |
Calymmian |
Platform covers expand. |
1600
[8] |
Paleo-
proterozoic |
Statherian |
First
complex single-celled life:
protists with nuclei.
Columbia is the primordial supercontinent. |
1800
[8] |
Orosirian |
The
atmosphere became
oxygenic.
Vredefort and
Sudbury Basin asteroid impacts. Much
orogeny. |
2050
[8] |
Rhyacian |
Bushveld Formation occurs.
Huronian glaciation. |
2300
[8] |
Siderian |
Oxygen Catastrophe:
banded iron formations result. |
2500
[8] |
Archean
[7] |
Neoarchean |
Stabilization of most
modern
cratons; possible
mantle overturn event. |
2800
[8] |
Mesoarchean |
First
stromatolites (probably
colonial
cyanobacteria). Oldest
macrofossils. |
3200
[8] |
Paleoarchean |
First known
oxygen-producing
bacteria. Oldest definitive
microfossils. |
3600
[8] |
Eoarchean |
Simple single-celled life (probably
bacteria and perhaps
archaea). Oldest probable
microfossils. |
3800 |
Hadean
[7][9] |
Lower Imbrian[10] |
|
c.3850 |
Nectarian[10] |
|
c.3920 |
Basin Groups[10] |
Oldest known
rock (4100 mya). |
c.4150 |
Cryptic[10] |
Formation of
earth (4570
mya). Oldest known
mineral (4400 mya). |
c.4570 |