Geologic Time

Scroll through the page below to get an idea of the immensity of geologic time.

Precambrian

  • First rocks
  • Oldest fossils of bacteria
  • Oldest fossils of eukaryotic cells
  • Algae and soft-bodied bilateral animals form
Cambrian

  • Animals diversify; some develop shells, external skeletons or notochords
Ordovician

  • Algae multiply
  • First fish
  • Plants and arthropods colonize land
Silurian

  • Vascular plants form and diversify
Devonian

  • Diversification of bony fishes
  • First amphibians and insects
Carboniferous

  • Forests of giant seed ferns cover the Earth
  • Reptiles form; amphibians are widespread
Permian

  • Reptiles spread
  • Origin of most present-day orders of insects
  • Mammal-like reptiles form
Triassic

  • Cone-bearing plants form
  • Dinosaurs spread
Jurassic

  • Dinosaurs and gymnosperm plants continue to diversify and spread
  • First birds and mammals form
Cretaceous

  • Origin and spread of flowering plants and hardwood trees
  • Dinosaurs become extinct
Paleogene

  • First primates
  • Whales and dolphins return to the sea
  • Earliest apes
Neogene

  • Common ancestor to both apes and humans
  • Oldest fossils of hominids; walked fully upright
Quaternary
Homo erectus appears
First civilization arises
Present day

APA format:

Genetic Science Learning Center. (2017, August 1) Geologic Time. Retrieved October 16, 2019, from https://learn.genetics.utah.edu/content/evolution/geologic/

CSE format:

Geologic Time [Internet]. Salt Lake City (UT): Genetic Science Learning Center; 2017 [cited 2019 Oct 16] Available from https://learn.genetics.utah.edu/content/evolution/geologic/

Chicago format:

Genetic Science Learning Center. "Geologic Time." Learn.Genetics. August 1, 2017. Accessed October 16, 2019. https://learn.genetics.utah.edu/content/evolution/geologic/.