Portal:Devonian

The Devonian Portal

A map of Earth as it appeared 390 million years ago during the Middle Devonian Epoch

The Devonian (/dəˈvoʊni.ən, dɛ-/ də-VOH-nee-ən, deh-) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at 419.62 million years ago (Ma), to the beginning of the succeeding Carboniferous period at 358.86 Ma. It is the fourth period of both the Paleozoic and the Phanerozoic. It is named after Devon, South West England, where rocks from this period were first studied.

The first significant evolutionary radiation of life on land occurred during the Devonian, as free-sporing land plants (pteridophytes) began to spread across dry land, forming extensive coal forests which covered the continents. By the middle of the Devonian, several groups of vascular plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants (pteridospermatophytes) appeared. This rapid evolution and colonization process, which had begun during the Silurian, is known as the Silurian-Devonian Terrestrial Revolution. The earliest land animals, predominantly arthropods such as myriapods, arachnids and hexapods, also became well-established early in this period, after beginning their colonization of land at least from the Ordovician period.

Fishes, especially jawed fish, reached substantial diversity during this time, leading the Devonian to be called the Age of Fishes. The armored placoderms began dominating almost every known aquatic environment. In the oceans, cartilaginous fishes such as primitive sharks became more numerous than in the Silurian and Late Ordovician. Tetrapodomorphs, which include the ancestors of all four-limbed vertebrates (i.e. tetrapods), began diverging from freshwater lobe-finned fish as their more robust and muscled pectoral and pelvic fins gradually evolved into forelimbs and hindlimbs, though they were not fully established for life on land until the Late Carboniferous. (Full article...)

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Selected Devonian Article

The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the Late Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago (Ma), with deformational, plutonic, and metamorphic events extending into the early Mississippian. The Acadian orogeny is the third of the four orogenies that formed the Appalachian Mountains and subsequent basin. The preceding orogenies consisted of the Grenville and Taconic orogenies, which followed a rift/drift stage in the Neoproterozoic. The Acadian orogeny involved the collision of a series of Avalonian continental fragments with the Laurasian continent. Geographically, the Acadian orogeny extended from the Canadian Maritime provinces migrating in a southwesterly direction toward Alabama. However, the northern Appalachian region, from New England northeastward into Gaspé region of Canada, was the most greatly affected region by the collision.

It was roughly contemporaneous with the Bretonic phase of the Variscan orogeny of Laurussia, with metamorphic events in southwestern Texas and northern Mexico, and with the Antler orogeny of the Great Basin. (Full article...)

List of selected Devonian articles
Sarcopterygii Trilobites Marcellus Formation Late Devonian extinction Bactritida List of Early Devonian land plants Dunkleosteus

Selected Devonian land plant article

Palhinhaea cernua with close-up of branch

Lycopodiopsida is a class of vascular plants also known as lycopsids, lycopods, or lycophytes. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching stems bearing simple leaves called microphylls and reproduce by means of spores borne in sporangia on the sides of the stems at the bases of the leaves. Although living species are small, during the Carboniferous, extinct tree-like forms (Lepidodendrales) formed huge forests that dominated the landscape and contributed to coal deposits.

The nomenclature and classification of plants with microphylls varies substantially among authors. A consensus classification for extant (living) species was produced in 2016 by the Pteridophyte Phylogeny Group (PPG I), which places them all in the class Lycopodiopsida, which includes the classes Isoetopsida and Selaginellopsida used in other systems. (See Table 2.) Alternative classification systems have used ranks from division (phylum) to subclass. In the PPG I system, the class is divided into three orders, Lycopodiales, Isoetales and Selaginellales. (Full article...)

List of selected Devonian articles
pteridophytes Sigillaria Pteridospermatophyta Lycophyte Equisetidae Progymnosperm Rhyniophyte Trimerophytopsida

Selected Devonian formation

The Hamilton Group is a Devonian-age geological group which is located in the Appalachian region of the United States. It is present in New York, Pennsylvania, Maryland, Ohio, West Virginia, northwestern Virginia and Ontario, Canada, and is mainly composed of marine shale with some sandstone.

There are two main formations encompassed by the group: the Mahantango Formation and the Marcellus Shale. In southwestern Virginia, where the two sub-units are not easily distinguishable, the Hamilton Group is broadly equivalent to the Millboro Shale or Millboro Formation.

The group is named for the village of Hamilton, New York. These rocks are the oldest strata of the Devonian gas shale sequence. (Full article...)

List of selected Devonian formation articles
Tully Formation Tioga Bentonites Windom shale Rhinestreet Formation Oriskany Formation Bakken formation Traverse Group New Albany Shale Old Red Sandstone Grey Downtonian

Selected Devonian fish article

Restoration

Gooloogongia (/ˌɡʊlʊˈɡɒŋɡiə/ GUU-luu-GONG-gee-ə) is a genus of prehistoric lobe-finned fish which belonged to the group of rhizodont fishes. Gooloogongia lived during the Late Devonian period (Famennian stage, about 360 million years ago). Fossils have been found in the Canowindra site, (Australia). It was named by Zerina Johanson and Per Ahlberg in 1998. In general size and shape Gooloogongia is similar to the modern saratoga which lives in the tropical rivers of northern Australia.

Gooloogongia loomesi ("Loomes' Gooloogong") named after Bruce Loomes, the foreman of the 1993 excavation of the Canowindra site, and the town of Gooloogong, NSW. (Full article...)

List of selected Devonian fish articles
Ctenaspis Brochoadmones Cheirolepis Holoptychius Hyneria Lepidaspis Scaumenacia Tinirau clackae Placoderm Diplocercides Dipterus Elpistostegalia Ventastega Tristichopteridae Phoebodus Stethacanthidae Xenacanthus

Selected Devonian invertebrate

Palaeocharinus rhyniensis life restoration at MUSE - Science Museum in Trento

Palaeocharinus is a genus of extinct trigonotarbid arachnids known from the Devonian of western Europe. The genus was first found and described in the Rhynie chert in the 1920s by Arthur Stanley Hirst and S. Maulik. The family to which the genus belongs may be paraphyletic. (Full article...)