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.