Silurian Period

Age of land plants and fish diversification

The Silurian Period (443-419 Ma) is in the Paleozoic Era, occurring after the Ordovician Period and before the Devonian Period.

Přídolí Epoch: 423.0±2.3–419.2±3.2 Ma
Ludlow Epoch: 427.4–423.0 Ma
- Ludfordian Age: 425.6±0.9–423.0±2.3 Ma
- Gorstian Age: 427.4±1.5–425.6±0.9 Ma
Wenlock Epoch: 433.4–427.4 Ma
- Homerian Age: 430.5±0.7–427.4±0.5 Ma
- Sheinwoodian Age: 433.4±0.8–430.5±0.7 Ma
Llandovery Epoch: 443.8–433.4 Ma
- Telychian Age: 438.5±1.1–433.4±0.8 Ma
- Aeronian Age: 440.8±1.2–438.5±1.1 Ma
- Rhuddanian Age: 443.8±1.5–440.8±1.2 Ma

The climate changes dramatically during this Period
- The early Silurian was a time of global ice-house climate that included great ice sheets at high latitudes
- During the middle of Llandovery the climate becomes warmer
- The world during this time has distinct north-south climatic zones
Plate tectonic activity shifts continents
- Gondwana drifted farther across the South Pole
- Siberia, Laurentia, and Baltica clustered around the equator.
- Laurentia and Baltica collided at the end of the Silurian, forming a new supercontinent, Euramerica, and raising new mountain ranges.
Formation of extensive evaporite (salt) deposits near the equator.
Large glacier melt and sea levels rise
Nearly continuous sea from New York to Nevada, and other shallow seas still covered parts of other continents
Mean oxygen levels in the atmosphere: 19%
Mean carbon dioxide levels in the atmosphere: 4,600 ppm
The earliest record of fire on Earth from 430 Ma (Glasspool & Gastaldo 2022)

Flora

Bryophytes diversify on landscape
The earliest polysporangiophyte macro-fossils found during Silurian
- Branching and vascular plants appear at the end of Silurian
- No evidence of euphyllophytes on the landscape at this point.

Fungi

Diversification of land fungi
- Tortotubus protuberans, a possible land-dwelling fungus from 440 Ma sediments in Sweden (Smith 2016).
  - Tortotubus is an ancient dikaryotic fungus (Ascomycete or Basidiomycete)

Fauna

Coral reefs first appear
Relatives of spiders, scorpions, millipedes and centipedes first appear
- The first flying insects probably appear during this time
Evolution of fishes; diversification of jawless fish