Life over Time

Eon
Era
Period
Major Events MYA
Phanerozoic
Cenozoic Quaternary Human evolution 2.6
Neogene Modern mammal and bird families become recognizable. Ancestor of apes. 23
Paleogene Extinction of the non-avian dinosaurs. Mammals diversify. Evolution and dispersal of flowering plants.
Chicxulub impact and the K-Pg extinction event.
66
Mesozoic Cretaceous Flowering plants proliferate, along with new insects. Many new types of dinosaurs evolve, as do modern crocodilians and sharks. Birds toothed and toothless coexist with pterosaurs. Marsupials and placental mammals appear. 145
Jurassic Gymnosperms (especially conifers, Bennettitales and cycads) and ferns common. Many types of dinosaurs. Mammals common but small. First birds and lizards. 201
Triassic Archosaurs dominant on land as dinosaurs and in the air as pterosaurs. First mammals and crocodilia appear. Dicroidium flora common on land. Modern corals and insects appear. 251
Paleozoic Permian Permian-Triassic extinction event occurs (251 MYA): 95% of life on Earth becomes extinct.
Coal-age flora are replaced by cone-bearing gymnosperms and by the first mosses. Beetles and flies evolve.
295
Carbon-
iferous
Winged insects radiate suddenly; some are quite large. Amphibians common and diverse. First reptiles and coal forests (scale trees, ferns, club trees, giant horsetails, Cordaites, etc.).
Large primitive trees, first land vertebrates, and amphibious sea-scorpions live amid coal-forming coastal swamps. Lobe-finned rhizodonts are dominant big fresh-water predators. In the oceans, early sharks are common and quite diverse. Corals very common, but trilobites and nautiloids decline.
359
Devonian First seed-bearing plants. First trees, 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. 419
Silurian First vascular plants. First jawed fishes, as well as many armoured jawless fish, populate the seas. Sea-scorpions reach large size. Tabulate and rugose corals, brachiopods, and crinoids all abundant. Trilobites and mollusks diverse; graptolites not as varied. 444
Ordovician First life on land.
(green plants and fungi)
Invertebrates diversify into many new types (e.g., long straight-shelled cephalopods). Early corals, articulate brachiopods, 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.
445
Cambrian Cambrian Explosion. Most modern animal phyla appear. First chordates appear, along with a number of extinct, problematic phyla. Trilobites, priapulid worms, sponges, inarticulate brachiopods, and numerous other animals. Anomalocarids are giant predators, while many Ediacaran fauna die out. 541
Proterozoic
Neo-
proterozoic
Ediacaran First multi-celled animals.
Ediacaran biota flourish worldwide in seas. Possible worm-like Trichophycus. First sponges and trilobitomorphs.
635
Cryogenian "Snowball Earth" 720
Tonian First simple multi-celled eukaryotes. 1000
Meso-
proterozoic
Ectasian Green algae colonies in the seas. 1600
Paleo-
proterozoic
Statherian First complex single-celled life: protists with nuclei, Francevillian biota. 2500
Archean
Neoarchean Oxygenic photosynthesis first evolves. 2800
Mesoarchean First stromatolites (probably colonial cyanobacteria). Oldest macrofossils. 3200
Paleoarchean First known oxygen-producing bacteria. Oldest definitive microfossils. 3600
Eoarchean Simple single-celled life (probably bacteria and archaea). Oldest probable microfossils. The first life forms and self-replicating RNA molecules evolve. 4000
Hadean
Early
Imbrian
Indirect photosynthetic evidence of primordial life (e.g., kerogen). 4130
Nectarian First life on Earth.
Eukaryotes
4280
Basin Groups End of the Early Bombardment Phase.
Asteroids and comets bring water to Earth.
4533
Cryptic Formation of Moon (4,500 MYA), probably from giant impact.
Formation of Earth (4,570 MYA), Early Bombardment Phase begins.
Formation of Sun (4,650 to 4,630 MYA).
4700

Published: August 27 2020