Portal:Devonian

Portal topics: Activities; Culture; Geography; Health; History; Mathematics; Nature; People; Philosophy; Religion; Society; Technology; Random portal

The Devonian Portal

Map of the Earth during the late Devonian, c. 370 Ma.

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 419.2 million years ago (Ma), to the beginning of the succeeding Carboniferous period at 358.9 Ma. 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 often be dubbed 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...)

Refresh with new selections below (purge)

Selected Devonian Article

From top to bottom and left to right, examples of sarcopterygians: Guiyu oneiros, West Indian Ocean coelacanth, Australian lungfish and the tetrapodomorph Panderichthys rhombolepis.

Sarcopterygii (/ˌsɑːrkɒptəˈrɪdʒi.aɪ/; from Ancient Greek σάρξ (sárx) 'flesh', and πτέρυξ (ptérux) 'wing, fin') — sometimes considered synonymous with Crossopterygii (from Ancient Greek κροσσός (krossós) 'fringe') — is a clade (traditionally a class or subclass) including both a group of bony fish commonly referred to as lobe-finned fish, and tetrapods. They are characterised by prominent muscular limb buds (lobes) within their fins, which are supported by articulated appendicular skeletons. This is in contrast to the other clade of bony fish, the Actinopterygii, which have only skin-covered bony spines supporting the fins.

The tetrapods, a mostly terrestrial superclass of vertebrates, are now recognized as having evolved from sarcopterygian ancestors and are most closely related to lungfishes. Cladistically, this would make the tetrapods a subgroup of Sarcopterygii and thus sarcopterygians themselves. As a result, the phrase "lobe-finned fish" normally refers to not the entire clade but only its members which are not tetrapods.

Non-tetrapod sarcopterygians were once the dominant predators of freshwater ecosystems during the Carboniferous and Permian periods, but suffered significant decline after the Great Dying. The only known extant non-tetrapod sarcopterygians are the two species of coelacanths and six species of lungfishes. (Full article...)

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

Selected Devonian land plant article

Fossil of Psilophyton dawsonii

Trimerophytopsida (or Trimeropsida) is a class of early vascular plants from the Devonian, informally called trimerophytes. It contains genera such as Psilophyton. This group is probably paraphyletic, and is believed to be the ancestral group from which both the ferns and seed plants evolved. Different authors have treated the group at different taxonomic ranks using the names Trimerophyta, Trimerophytophyta, Trimerophytina, Trimerophytophytina and Trimerophytales. (Full article...)

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

Selected Devonian formation

The Tioga Bentonites are a series of ash bed layers occurring in three Sedimentary basins in the eastern and midwestern United States. The primary basin they are found in is the Appalachian Basin, as well as the Illinois Basin and the Michigan Basin. Due to an unconformity these ash beds are not present in the southern Appalachians. (Full article...)

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

Selected Devonian fish article

Panderichthys

Elpistostegalia is a clade containing Panderichthys and all more derived tetrapodomorph taxa. The earliest elpistostegalians, combining fishlike and tetrapod-like characters, such as Tiktaalik, are sometimes called fishapods. Although historically Elpistostegalia (often spelled Panderichthyida) was considered an order of prehistoric lobe-finned fishes, it was cladistically redefined to include tetrapods. (Full article...)

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

Selected Devonian invertebrate

Amphipora is an extinct genus of sponges, and type genus of the extinct family Amphiporaidae. Species are known from the Silurian to Devonian, over much of the northern hemisphere. (Full article...)