The Ordovician Button for link to Chinese version of this page
The Ordovician was a period of about 60 million years, that passed between 510 to 438 million years ago (some authorities begin the age at 490 million years ago and some have it ending 443 or 440 million years ago). During the Ordovician most organisms that have left us fossil records were living the shallow seas, and there was very little life on the land surface. The seas were full of brachiopods, crinoids, trilobites, and conodonts. Scottish fossils of conodonts soft tissue show that these creatures had some resemblance to lampreys. Toward the end of the Ordovician there was a mass extinction event.

 
Links about the Paleozoic:
  1. The U Cal Berkeley Ordovician page.
  2. The Palaeos Ordovician page.
  3. A BBC news item about a possible gamma burst cause for a mass extinction toward the end of the Ordovician.
  4. A map of the Middle Ordovician Earth.

Ordovician Fauna (Actinoceras)

The two cephalopods above (Actinoceras bigsbyi) and the crinoids behind them (Cupulocrinus plattesvillensis is orange and Glyptocrinus charitoni is purple) lived in the shallow seas over Illinois in the middle Ordovician, about 470 million years ago. These specimens can be found in the Illinois State Museum in Springfield, IL.

 
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