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