Ordovician Period

Geologic Age

• 485.4–443.8 million years ago

Subdivisions

• Late Ordovician: 458.4–443.8 million years ago

  • Hirnantian: 445.2±1.4–443.8±1.5 Ma

  • Katian: 453.0±0.7–445.2±1.4 Ma

  • Sandbian: 458.4±0.9–453.0±0.7 Ma

• Middle Ordovician: 470.0–458.4 million years ago

  • Darriwilian: 467.3±1.1–458.4±0.9 Ma

  • Dapingian: 470.0±1.4–467.3±1.1 Ma

• Early Ordovician: 485.4–470.0 million years ago

  • Floian: 477.7±1.4–470.0±1.4 Ma

  • Tremadocian: 485.4±1.9–477.7±1.4 Ma

What happened during this time?

Geophysical

• • 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

Biological

Flora

• Algae were dominant in the oceans

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

• Evidence for the earliest land plants

  • Spores from land plants in the Early Ordovician indicating the presence of bryophytes and eophytes

  • Potential macro-fossil evidence of liverworts, hornworts, and mosses by the Middle Ordovician (Retallack, 2019)

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

Fungi

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

Nematophytes

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

Fauna

• Diversification of invertebrates

  • First insects appear around 480 Ma

• Origin of vertebrates (fish)