Carboniferous

The Carboniferous (/ˌkɑːrb.əˈnɪf.ər.əs/ KAHR-bə-NIF-ə-rəs) is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago (Mya), to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means 'coal-bearing' and derives from the Latin words carbō ('coal') and ferō ('I bear, I carry'), and was coined by geologists William Conybeare and William Phillips in 1822.Late Pennsylvanian: Gzhelian (most recent)Aviculopecten subcardiformis; a bivalve from the Logan Formation (Lower Carboniferous) of Wooster, Ohio (external mold).Bivalves (Aviculopecten) and brachiopods (Syringothyris) in the Logan Formation (Lower Carboniferous) in Wooster, Ohio.Syringothyris sp.; a spiriferid brachiopod from the Logan Formation (Lower Carboniferous) of Wooster, Ohio (internal mold).Palaeophycus ichnosp.; a trace fossil from the Logan Formation (Lower Carboniferous) of Wooster, Ohio.Crinoid calyx from the Lower Carboniferous of Ohio with a conical platyceratid gastropod (Palaeocapulus acutirostre) attached.Conulariid from the Lower Carboniferous of Indiana.Tabulate coral (a syringoporid); Boone Limestone (Lower Carboniferous) near Hiwasse, Arkansas.The late Carboniferous giant dragonfly-like insect Meganeura grew to wingspans of 75 cm (30 in).The gigantic Pulmonoscorpius from the early Carboniferous reached a length of up to 70 cm (28 in).Akmonistion of the shark order Symmoriida roamed the oceans of the early Carboniferous.Falcatus was a Carboniferous shark, with a high degree of sexual dimorphism.The amphibian-like Pederpes, the most primitive Mississippian tetrapodHylonomus, the earliest sauropsid reptile, appeared in the Pennsylvanian.Petrolacosaurus, the first diapsid reptile known, lived during the late Carboniferous.Archaeothyris was a very early synapsid and the oldest known. The Carboniferous (/ˌkɑːrb.əˈnɪf.ər.əs/ KAHR-bə-NIF-ə-rəs) is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago (Mya), to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means 'coal-bearing' and derives from the Latin words carbō ('coal') and ferō ('I bear, I carry'), and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern 'system' names to be employed, and reflects the fact that many coal beds were formed globally during that time. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial animal life was well established by the Carboniferous period. Amphibians were the dominant land vertebrates, of which one branch would eventually evolve into amniotes, the first solely terrestrial vertebrates. Arthropods were also very common, and many (such as Meganeura) were much larger than those of today. Vast swaths of forest covered the land, which would eventually be laid down and become the coal beds characteristic of the Carboniferous stratigraphy evident today. The atmospheric content of oxygen also reached its highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. The later half of the period experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change. In the United States the Carboniferous is usually broken into Mississippian (earlier) and Pennsylvanian (later) subperiods. The Mississippian is about twice as long as the Pennsylvanian, but due to the large thickness of coal-bearing deposits with Pennsylvanian ages in Europe and North America, the two subperiods were long thought to have been more or less equal in duration. In Europe the Lower Carboniferous sub-system is known as the Dinantian, comprising the Tournaisian and Visean Series, dated at 362.5-332.9 Ma, and the Upper Carboniferous sub-system is known as the Silesian, comprising the Namurian, Westphalian, and Stephanian Series, dated at 332.9-298.9 Ma. The Silesian is roughly contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, and the Westphalian as the Coal Measures and Pennant Sandstone. The International Commission on Stratigraphy (ICS) faunal stages (in bold) from youngest to oldest, together with some of their regional subdivisions, are: A global drop in sea level at the end of the Devonian reversed early in the Carboniferous; this created the widespread inland seas and the carbonate deposition of the Mississippian. There was also a drop in south polar temperatures; southern Gondwanaland was glaciated throughout the period, though it is uncertain if the ice sheets were a holdover from the Devonian or not. These conditions apparently had little effect in the deep tropics, where lush swamps, later to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major marine extinction, one that hit crinoids and ammonites especially hard. This sea level drop and the associated unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation.