Ordovician Period

Age of the earliest land plants

The Ordovician Period (485-444 Ma) is in the Paleozoic Era, occurring after the Cambrian Period and before the Silurian Period.

Geologic Age

  • 485.4–443.8 million years ago


What happened during this time?


    • The carbon dioxide levels hover around ~5,000 ppm during this Period

    • Oxygen levels are relatively stable during this time at 17%

    • The Taconic progeny forms a mountain chain formed from eastern Canada down through the East coast of the United States

      • Portions of the range are represented by the Appalachian Mts

    • The appearance of early land plants (bryophytes, eophytes) may have helped trigger the 2nd largest glaciation event (Lenton et al. 2012)



  • Algae were dominant in the oceans

    • Probable autotrophs on the land, such as soil algae or bacteria

  • Evidence for the earliest land plants


  • Terrestrial fungi-like organisms, such as Prototaxites, are some of the largest organisms on the landscape at 15 cm tall

  • Mycorrhizal fungi, related to the glomeromycetes, are found in associated with land plants and Prototaxites


  • Diversification of invertebrates

    • First insects appear around 480 Ma

  • Origin of vertebrates (fish)