Ordovician
Geologic period
>
The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period 485.4 Ma to the start of the Silurian Period 443.8 Ma. Wikipedia
Occurred: 485.4 (+/- 1.9) million years ago - 443.8 (+/- 1.5) million years ago
Era: Paleozoic
Epochs: Early Ordovician, Middle Ordovician, and Upper Ordovician
Chronological unit: Period
First proposed by: Charles Lapworth, 1879
Lower boundary definition: FAD of the Conodont Iapetognathus fluctivagus
Lower boundary GSSP: Greenpoint section, Green Point, Newfoundland, Canada; 49°40′58″N 57°57′55″W / 49.6829°N 57.9653°W