Mississippian
Geologic period
The Mississippian is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. Wikipedia
Occurred: 359.2 million years ago - 318.1 million years ago
Period: Carboniferous
Lower boundary definition: FAD of the Conodont Siphonodella sulcata (discovered to have biostratigraphic issues as of 2006)
Lower boundary GSSP: La Serre, Montagne Noire, France; 43°33′20″N 3°21′26″E / 43.5555°N 3.3573°E
Lower GSSP ratified: 1990
Upper boundary definition: FAD of the Conodont Declinognathodus nodiliferus
Ages: Tournaisian, Viséan, and Serpukhovian