The Ordovician Period
When was it?
505 to 438 million years ago.
What was going on?
Further diversification, then a big mass extinction.
What were the continents like?
Still distributed much like the Cambrian, but towards the end of the Ordovician, Godwanaland
had moved very close to the South pole, and the climatic consequences are believed to have
contributed to a mass extinction at the end of the period..
What kind of life existed?
Further evolved from the cambrian, but fairly similar -- jawless fishes, our distant ancestors,
which had appeared in the late Cambrian, become more common.