Other forms: Mississippians
The Mississippian is the fifth geologic period of the Paleozoic era, lasting from about 359 to 323 million years ago. It is often referred to as the "Age of Crinoids," marine animals sometimes called "sea lilies."
During the Mississippian period, crinoids and other marine animals, such as filter-feeding brachiopods (shellfish resembling clams) flourished in the warm, shallow seas that covered much of what is now North America. There were early sharks, too. These organisms contributed to the massive limestone deposits that were first studied in the Mississippi River region. Vertebrates were moving onto land, and early amphibians evolved. Colliding land masses eventually pushed up the Appalachian Mountains. In Europe, the Mississippian is known as the Lower Carboniferous period.