Carboniferous

The Carboniferous period dates from 360 million to 280 million years ago. It gets its name from the vast deposits of coal produced when fluctuating seas drowned the tropical forests that covered much of North America and Europe.

The later Paleozoic (286 million to 570 million years ago) was a world that would be recognizable to us. By this time the teeming marine and land plants had expelled enough oxygen to produce an atmosphere very similar to our own. Vast forests greened the supercontinent Pangaea and supported a thriving animal population. We would be struck by the sheer size and variety of the flora and fauna: horsetails and scale trees that stood from 50 to 100 feet tall and dragonflies with 2-foot wingspans. Drippingly humid and silent, the monotonously green rain forest abounded with scuttling creatures familiar and unfamiliar. Animals that swam, crawled, and flew populated the tropical swamps of the forest. Snails and cockroaches and myriapods made a living on the rich forest floor, along with 6-foot centipedes and crocodile-like amphibians.

By this time all the major characters of evolution had come into being. There would still be millennia of ingenious refinements of size and shape and function, variations on the main themes to exploit the new Devonian (408 million to 438 million years ago) environment of land and air. The Phylum Chordata, comprised of animals with backbones, had previously experimented with fishes and amphibians; now, in the Carboniferous period, the chordates would diverge into reptiles.

In a remarkable adaptation referred to as the amniote radiation, amphibians had evolved from needing large bodies of water in order to reproduce. The method was a semipermeable, shelled or leathery skinned egg filled with enough nutrients to sustain an embryo until it was fully developed. This dry-land form of reproduction necessitated yet another biological innovation, namely internal fertilization. These two features enabled the former amphibians to radiate out into every niche of the giant land mass, in turn encouraging further evolutionary branching. As the tetrapods (fourlimbed animals) spread through the luxuriant vegetation, they made adjustments in their dentition and digestive tracts to take advantage of the untapped food source on land.

Three distinct groups of reptiles emerged, differentiated by the number of small holes in the skull located behind the eyes at either side. Anapsids had no holes and included the turtles and their now-extinct relatives. Synapsids, with a single pair of temporal openings, included all of the mammal-like reptiles, now extinct, and their distant relatives, the true mammals. Diapsids were reptiles with two pairs of openings. Petrocalosaurus was a rapid, 16-inch insectivore whose genes gave rise to lizards, snakes, crocodiles, dinosaurs, and birds.

By the Carboniferous period, the constant ebb and flow of continental drift had once again pushed the land masses back together into one supercontinent, Pangaea, whose northern forests were periodically flooded by shallow tropical seas. The cycle of vegetation and flooding produced organic beds of peats that were compressed into coal layers over 3,000-feet thick. Exquisitely preserved fossils appear in this coal, especially near the Czech mining town of Nyrany. Here, hundreds of specimens have been collected, representing twenty amphibian and four reptile species as well as unusual fishes and small, shrimplike creatures.

In the Carboniferous seas, huge limestone reefs were being laid down by limy coral, brachiopod, and crinoid skeletons. These reefs were home to starfish, gastropods , and sea urchins, while giant coiled nautiloids and bony fish swam overhead.

see also Geological Time Scale.

Nancy Weaver

Bibliography

Asimov, Isaac. Life and Time. Garden City, NY: Doubleday and Company, 1978.

Fortey, Richard. Fossils: The Key to the Past. Cambridge, MA: Harvard University Press, 1991.

———. Life: A Natural History of the First Four Billion Years of Life on Earth. New York: Viking Press, 1998.

Friday, Adrian, and David S. Ingram, eds. The Cambridge Encyclopedia of Life Sciences. London: Cambridge University Press, 1985.

Gould, Stephen Jay, ed. The Book of Life. New York: W. W. Norton and Company, 1993.

Lambert, David. The Field Guide to Prehistoric Life. New York: Facts on File, 1985.

McLoughlan, John C. Synapsida: A New Look into the Origin of Mammals. New York: Viking Press, 1980.

Steele, Rodney, and Anthony Harvey, eds. The Encyclopedia of Prehistoric Life. New York: McGraw Hill, 1979.

Wade, Nicholas, ed. The Science Times Book of Fossils and Evolution. New York: The Lyons Press, 1998.

CARBONIFEROUS OR MISSISSIPPIAN AND PENNSYLVANIAN?

In the United States, the Carboniferous Period is usually broken down into two periods— Mississippian and Pennsylvanian. Sedimentary rocks that formed in shallow oceans characterize the Mississippian or "Lower Carboniferous." These rocks are usually found along the Mississippi River. Coal bearing sedimentary rocks that formed in swamps and river deltas characterize the Pennsylvanian or "Upper Carboniferous. These rocks are usually found in the northeastern United States.

Carboniferous Penultimate period of the Palaeozoic Era, preceded by the Devonian and followed by the Permian. It began about 362.5 Ma ago and ended about 290 Ma ago. In Europe the lower part of the system is termed the Dinantian. It is divided into two series and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast the upper part, the Silesian, which is subdivided into three series, is noted for the deposition of terrestrial and freshwater sediments. The vast forests of the Upper Carboniferous gave rise to the rich coal measures of south Wales, England, Scotland, and many other areas worldwide. N. American geologists subdivide the Carboniferous System into two subsystems. Of these the lower (362.5–322.8 Ma ago) is named the Mississippian and is the equivalent of the Dinantian sub-System plus the lower part of the Silesian sub-System. The upper sub-system, the Pennsylvanian (322.8–290 Ma ago), is the equivalent of most of the Silesian.

Carboniferous The penultimate period of the Palaeozoic Era, from about 360–286 Ma ago, preceded by the Devonian and followed by the Permian. In Europe the lower part of the period is termed the Dinantian. It is divided into two stages and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast, the upper part, the Silesian, which is subdivided into three stages, is noted for the deposition of terrestrial and freshwater sediments. N. American geologists subdivide the Carboniferous into two periods or subperiods. Of these the lower is named the Mississippian and is the equivalent of the Dinantian stages (the Tournaisian and Visean). The upper period, the Pennsylvanian, is the equivalent of the Silesian. During the Carboniferous, very lush, swamp forests dominated the landscape in low-lying areas, where minor changes in sea-level alternately exposed land supporting forest then inundated and buried the vegetation. The forests were dominated by Lycopsida and Calamitaceae, some of which grew to the size of trees (see CALAMITES CISTIIFORMES and LEPIDODENDRON SELAGINOIDES), and the forest floor supported ferns and seed ferns. The buried vegetation was compressed and changed through time to form the rich coal measures of southern Wales, England, Scotland, the USA, and many other areas world-wide, in which recognizable seed plants are common fossils.

Carboniferous The penultimate period of the Palaeozoic Era, preceded by the Devonian and followed by the Permian. It began about 362.5 Ma ago and ended about 290 Ma ago. In Europe the lower part of the system is known as the Dinantian. It is divided into two stages and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast the upper part, the Silesian, which is subdivided into three stages, is noted for the deposition of terrestrial and freshwater sediments. North American geologists subdivide the Carboniferous System into two periods or subperiods. Of these the lower (362.5–322.8 Ma ago) is called the Mississippian and is the equivalent of the Dinantian stages (the Tournaisian and Visean) plus the lower part of the Silesian. The upper period, the Pennsylvanian (322.8–290 Ma ago), is the equivalent of most of the Silesian. During the Carboniferous very lush, swamp forests dominated the landscape in low-lying areas, where minor changes in sea level alternately exposed land supporting forest then inundated and buried the vegetation. The climate was very humid until the end of the period, when it became arid, conditions then selecting against seed-bearing plants. The forests were dominated by Lycopsida and Calamitaceae, some of which grew to the size of trees (e.g. Lepidophloios species grew up to 50 m tall) and the forest floor supported ferns and seed ferns. The first tetrapods (e.g. the amphibian Ichthyostega) appeared very early in the Carboniferous. The buried vegetation was compressed and changed through time to form the rich coal measures of southern Wales, England, Scotland, the USA, and many other areas worldwide, in which recognizable seed plants are common fossils.

Carboniferous The penultimate period of the Palaeozoic Era, from about 359.2–299 Ma ago, preceded by the Devonian and followed by the Permian. In Europe the lower part of the period is termed the Dinantian. It is divided into three stages and is characterized by marine limestones with a rich coral-brachiopod fauna. In contrast the upper part, the Silesian, which is subdivided into four stages, is noted for the deposition of terrestrial and freshwater sediments. The vast forests of the Upper Carboniferous gave rise to the rich coal measures of S. Wales, England, Scotland, and many other areas Worldwide. N. American geologists subdivide the Carboniferous into two sub-periods. Of these the lower is named the Mississippian and is the equivalent of the Dinantian stages (the Tournaisian, Visean, and Serpukhovian). The upper period, the Pennsylvanian, is the equivalent of the Silesian.