| Carboniferous period|
359 to 318 million years ago
The Early Carboniferous or Mississippian sub-period lasted for about 40 million years. During that time animal life, both vertebrate and invertebrate, consolidated its position on land the way plant life did during the Devonian. Euramerica and western Gondwana drifted northwards and moved closer together. This movement caused a lot of mountain building - the Varisca-Hercynian Orogeny - in Europe.
The American geologist Alexander Winchell formally proposed the name Mississippian in 1869 for the Lower Carboniferous strata (mostly limestones from limy mud laid down in a shallow sea) that are extensively exposed along the Upper Mississippi River drainage region. In 1891 H. S. Williams divided the "Carboniferous or Pennine" System into Pennsylvanian and Mississippian. In 1911 Ulrich divided the Mississippian into Waverleyan and Tennesseean systems.
The term Mississippian is used by American geologists and paleontologist but did not catch on in Europe or elsewhere, where Carboniferous was retained. The Mississippian and the "Lower Carboniferous" are not actually equivalent. Nevertheless some recent fiddling with boundaries has allowed the two to be matched and the Mississippian became a formal international term for the Early (Lower) Carboniferous, encompassing the Tournaisian, Viséan, and Serpukhovian Ages.
The Mississippian saw mountain building in what is now western North America. A glaciated Gondwana nears southern Euramerica and continues to collide with ancestral Europe, resulting in the Hercynian Orogeny and great mountains in southern Europe.
|Period/Epoch||Age||Faunal Stages||When began (Ma)||Duration (Ma)|
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Arthropods, corals, bryozoa, crinoids, and mollusks flourished in warm shallow seas. Echinoderms - especially Crinoids - were extremely numerous. Trilobites were much reduced in numbers, and confined to a single superfamily, the Proetoidea (also spelled Proeteacea). The last of the dendrite graptoloids died out. The first of the giant fusulinid foramnifers (marine amoebas) appear, but these are still tiny and insignificant
Of the nautiloid (palcephalopoda) cephalopods only the nautilida flourished. The giant straight-shelled Rayonnoceras, up to perhaps 6 meters in length, was the last of the Actinocerida. The bulbous-shelled Oncocerida also died out at this time. Many types of Ammonoid cephalopods evolved, mostly of the simple goniatiatic suture pattern. Especially in northwest Europe, their fossils are of great stratigraphic importance. The first ceratic ammonoids appear, with a more complex suture pattern.
Freshwater and Terrestrial Biota
There are major differences between Late Devonian and early Mississippian vegetation. Areas that were previously forest were now dominated by shrubby r-selected plants, mostly pteridosperms less than 2 meters in height. In other words, weeds. Only later did lycopsid and calamite trees reappear, paving the way for the giant forests of the late Carboniferous (Pennsylvanian) period.
The climate, originally hot and dry, became cooler and wet later in the Mississippian period. Plants became important ground cover in this lush new environment, producing shelter for invertebrates which in turn provided food for early tetrapods.
Terrestrial invertebrates are poorly known, but it is likely that they consisted of mites, scorpions and other arachnids, millipedes, arthropleurids, collembolans (springtails), and an increasing diversity of litter-reducing insects (e.g. blattoids). Some eurypterids of this time may have been partially terrestrial.
This was the period of greatest tetrapod evolutionary radiation. The early generations of aquatic ichthyostegids were replaced by various parallel lineages of labyrinthodont and lepospondyl amphibians. All the major ancient tetrapod groups seem to have appeared at this time. the majority were probably semi-aquatic, but early terrestrial forms and proto-reptiles appeared as well. The fresh-water rhizodontiform fish - tetrapod "uncles" that like lungfish were capable of breathing air on occasion - were the super predators of the swamps, streams and lakes, with Rhizodus attaining 5 to 6 meters in length.
The Mississippian terrestrial food chain seems to have been much more primitive and less efficient then that of today. The major link between plant productivity and animal consumers seems to have been, as in the Devonian, through detritivorous arthropods. Insect herbivory was only just beginning at the end of the Mississippian sub-period, and tetrapod herbivory unknown. Most insects and arachnids scrounged for food in leaf litter, and served as the primary food source for the early terrestrial tetrapods.
During this period there seems to have been only a single tetrapod province, although that may be because all known tetrapod fossils of this age are from tropical Euramerica; there are none known further than 5 degrees north or 20 degrees south of the Viséan paleoequator. It is not known whether this is because the rest of the world was uninhabitable to animal life at the time (due to the increasing polar ice age conditions) or simply because no other localities have yet been discovered.
- Browse the Fossil Gallery - Lower Carboniferous (Mississippian) Period - a nice selection of fossils from Nova Scotia
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page uploaded on Kheper Site on 27 May 1998, page uploaded on Palaeos Site 10 April 2002, last modified 4 May
text content by M. Alan Kazlev 1998-2002