The history of life as revealed by the fossil record.

ErasPeriodsEpochsAquatic LifeTerrestrial Life
With approximate starting dates in millions of years ago in parentheses. Geologic features in green
Cenozoic (65)
The "Age of Mammals"
Quaternary (1.8)RecentHumans in the new world
PleistocenePeriodic glaciationFirst humans
Continental drift continues
Tertiary (65)PlioceneAll modern groups presentHominids and pongids
MioceneMonkeys and ancestors of apes
OligoceneAdaptive radiation of birds
EoceneModern mammals and herbaceous angiosperms
Paleocene
Mesozoic (248)
"The Age of Reptiles"
Cretaceous (144)Still attached: N. America & N. Europe; Australia & Antarctica
Modern bony fishesExtinction of dinosaurs, pterosaurs
Extinction of ammonites, plesiosaurs, ichthyosaursRise of woody angiosperms, snakes
Africa & S. America begin to drift apart
Jurassic (213)Plesiosaurs, ichthyosaurs abundantDinosaurs dominant; first mammals
Ammonites again abundantFirst lizards; Archaeopteryx
Skates, rays, and bony fishes abundantInsects abundant
First angiosperms
Pangaea splits into Laurasia and Gondwana
Triassic (248)First plesiosaurs, ichthyosaursAdaptive radiation of reptiles:
thecodonts, therapsids, turtles,
crocodiles, first dinosaurs
Ammonites abundant at first
Rise of bony fishes
Paleozoic (590)Permian (286) Appalachian Mts. formed; periodic glaciation and arid climate
Extinction of trilobites, placodermsReptiles abundant: cotylosaurs, pelycosaurs. Cycads, conifers, ginkgos
Pennsylvanian (320)Warm, humid climate Together
the Pennsylvanian and Mississippian
make up the
"Carboniferous";
also called the
"Age of Amphibians"
Ammonites, bony fishesFirst reptiles
Coal swamps
Mississippian (360) Adaptive radiation of sharksForests of lycopsids, sphenopsids, and seed ferns
Amphibians abundant
Land snails
Periodic aridity
Devonian (408)
The "Age of Fishes"
Placoderms, cartilaginous and bony fishes. Ammonites, nautiloidsFerns, lycopsids, and sphenopsids
First gymnosperms and bryophytes
First insects
First amphibians
Extensive inland seas
Adaptive radiation of ostracoderms, eurypteridsFirst land plants, arachnids (scorpions)
Silurian (438)Mild climate; inland seas Nautiloids, Pilina, other mollusksNone
Ordovician (505)Mild climate, inland seasTrilobites abundant
First jawless vertebrates
Trilobites dominant
None
Cambrian (590)First eurypterids, crustaceans
Mollusks, echinoderms
Sponges, cnidarians, annelids
Tunicates
None
Periodic glaciation
Proterozoic (2500)
Archean (4500)
Fossils rare but many protistan and invertebrate phyla toward the endNone
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6 June 1999