Phanerozoic/Mississippian Period

From Wikiversity
Jump to navigation Jump to search

Rogelio Paz This page is under construction

The Mississippian Period takes place about 360 to 325 million years ago[1]. A part of the Carboniferous Period, named so because of the unconformity and the rocks marking the unconformity are different then those in Europe and found mainly in the American state of Mississippi.

Rocks[edit]

In the most part, coal was largely deposited during this time period. The rocks of the Mississippian Period are mostly limestones[2]. Much of this was deposited as limy mud in the shallow seas.

Mountain Building[edit]

Formation of Appalachian Mountains through time

The most notable occurrence of orogeny is the formation of the Appalachian Mountains, which were formed when continents of Laurasia crashed with Gondwanaland. What is now North America and Africa collided to form the southern Appalachian Mountains. The Appalachians formed due to three major orogenic events: the Taconic orogeny, Acadian orogeny, and Allegheny orogeny.

Animal Life[edit]

This time period saw a reduction of trilobites and an increase in marine life such as corals and mollusks. The large amounts of Mississippian limestone found demonstrate the great diversity in crinoids. Sharks, acanthodians, and sarcopterygian fishes were diverse, while placoderms began to die out[3].

Fish had evolved into tetrapods such as ichthyostegas, during the Devonian period. These animals, although still fish, were one step closer to becoming land animals through the development of "arms and feet" like appendages. This led to amphibians which were making the transition from oceans to land. Labyrinthodonts were mainly swamp based animals who fed on insects, fish, and even each other[4]. These animals lived mainly on solid land, returning to the water only to reproduce. The oldest fossils of amniotic animals can be found dated back the the Late Mississippian. This marked a significant achievement in the evolution of animals as they could finally reproduce without the need to return to water. These animals were reptiles such as the Petrolacosaurus.

References[edit]

  1. http://www.watersheds.org/earth/gtime02e.htm
  2. http://tapestry.usgs.gov/ages/carboniferous.htm
  3. Levin, Harold, (2006), The Earth Through Time, 8th ed, John Wiley & Sonc, Inc. NJ.
  4. http://www.palaeos.com/Paleozoic/Carboniferous/Mississippian.htm