"The Middle Mississippian is the second of three subepochs of the Mississippian epoch of the Carboniferous period. It spans the time between 345.3 \u00B1 2.1 Ma and 326.4 \u00B1 1.6 Ma (million years ago). It has one faunal stage, the Visean."@en . . . . "The Middle Mississippian is the second of three subepochs of the Mississippian epoch of the Carboniferous period. It spans the time between 345.3 \u00B1 2.1 Ma and 326.4 \u00B1 1.6 Ma (million years ago). It has one faunal stage, the Visean."@en . . "Middle Mississippian"@en . .