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Period: to
J Armestar Perioid 3
Geological Timescale -
Precambrian #1 Event:19
The presence of stromatolites indicates that shallow seas covered much of Earth during intervals in this period. -
Precambrian #2
Nearly half of the valuable mineral deposits in the world occur in the rock in this period -
Cambrian #1 Event:18
Trilobites Appear -
Cambrian #2
Shelled brachiopods appear -
Ordovician #1 Event:17
There is very little plant life during this period -
Ordovician #2
Colonies of tiny invertebrates call graptolites flourished and vertebrates appear, fish did not have jaws or teeth and their bodies were covered with bony plates