Geological History


Geological History Across Geologic Time

Updated Geological History


Link to equivalent chart with Paleobiology:
"visit links within the table for more information"






Geologic Time is divided and subdivided into various categories as presented here:
Eons are divided into Eras; Eras are divided Periods; Periods and subperiods are divided into Epochs
(Epochal subdivisions referred to as "ages" are not given in the chart)











Phanerozoic EON
(544 mya to present)

"The age of visible life"

Evolutionary Milstones

Cenozoic Era
(65 mya to today)

Quaternary (1.8 mya to today)

Holocene (11,000 years to today) Modern man radiates, "science" appears and eventually computers and the Internet become ubiquitous.
Pleistocene (1.8 mya to 11,000 yrs)Neandertals appear and disappear; Homo erectus and Homo sapiens appear
Tertiary (65 to 1.8 mya)Pliocene (5 to 1.8 mya)Ape-like ancestors of modern humans (Hominids), the australopithecines
Miocene (23 to 5 mya) Grazing horses, antelopes appear
Oligocene (38 to 23 mya)

Radiation of more modern animals: most modern bird forms have appeared; most modern mammals have appeared.

Eocene (54 to 37 mya)First grasses appear, a resource for herbovores; trees thrive. Some modern mammals appear: advanced primates; camels, cats, dogs, horses & rodents
Paleocene (65 to 54 mya)Flowering plants begin radiation extending through the Eocene. Small mammals radiate
Mesozoic Era
(245 to 65 mya)

Cretaceous (146 to 65 mya)





Major extinction includes dinosaurs and ammonites (K-T)
Appearances include: flowering plants (angiosperms); lizards; placental animals (early mammals); snakes; social insects; marsupial and primitive placental animals
Modern insect forms radiate

Jurassic (208 to 146 mya) Appearances include birds; crabs; frogs and salamanders
Dinosaurs radiate to dominate the land
Triassic (245 to 208 mya) Breakup of Pangaea begins
Major extinction event: tabulate corals and conodonts disappear - ammonoids, reptiles and amphibians decimated
Appearances include: dinosaurs; crocodiles; marine reptiles; turtles;
Pterosauria and mammals
Major groups of seed plants appear


Paleozoic Era
(544 to 245 mya)

Permian (286 to 245 mya)

Major extinction of invertebrates (P-T). Trilobites fade away forever. All but articulate crinoids dissapear
Seedplants producing large trees

(360 to 286 mya)
Pennsylvanian (325 to 286 mya) Conifers & many winged insects appear
Mississippian (360 to 325 mya) Reptiles appear. Trilobites become scarce
Devonian (410 to 360 mya)Mass extinction (F-F)
Land colonized by plants and animals
Appearances include: insects; sharks; amphibians (tetrapods); lung fishes and earliest seed plants.
Extensive radiation of fishes.
Silurian (440 to 410 mya)Jawed fish, cartilaginous fish and vascular plants appear. Primitive terrestrial predators: Arachnids.
Ordovician (500 to 440 mya) Mass extinction
First land plants; bryozoans appear. Trilobites begin to specialize.
Cambrian (544 to 500 mya) Tommotian (530 to 527 mya)Appearance of hard parts and vision - fossils become common. Appearances include: vertebrates; jawless fish; small shelly animals; conodonts; trilobites radiate repeatedly and reach their peak diversity.First major radiation of animals


Precambrian Time
(4,500 to 544 mya)

"deep time on earth"

Proterozoic Era
(2500 to 544 mya)
Vendian (650 to 544 mya) or Ediacaran
No Epochs

Cold climate with glaciation in late Proterozoic

Neoproterozoic (900 to 544 mya) - Late

Rodinia supercontinent splits (.75 ba) forming Panthalassic Ocean

Mesoproterozoic (1600 to 900 mya) - MiddleRodinia supercontinent forms (1.1 ba)
Paleoproterozoic (2500 to 1600 mya) - Early.

(3800 to 2500 mya)

Toxic atmosphere of ammonia methane and other gases
Formation of stromatolites

(4500 to 3800 mya)
Earth's environment extremely hostile to life as we know it.
Oldest rocks form (3.8 ba)
Sun forms and planets coalesce
Dawn of Time (13,700 mya)The Big Bang (13,700 mya)

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