The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago (Mya), to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, England, where rocks from this period were first studied.
The PaleozoicEra is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from 541 to 251.902 million years ago, and is subdivided into six geologic periods : the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era.
The Falls of the Ohio National Wildlife Conservation Area is a national, bi-state area on the Ohio River near Louisville, Kentucky in the United States, administered by the U.S. Army Corps of Engineers. Federal status was awarded in 1981. The falls were designated a National Natural Landmark in 1966.
The Variscan or Hercynianorogeny is a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea.
Hynerpeton is an extinct genus of early four-limbed vertebrate that lived in the rivers and ponds of Pennsylvania during the Late Devonian period, around 365 to 363 million years ago. The only known species of Hynerpeton is H. bassetti, named after the describer's grandfather, city planner Edward Bassett. Hynerpeton is known for being the first Devonian four-limbed vertebrate discovered in the United States, as well as possibly being one of the first to have lost internal (fish-like) gills.
The order Trigonotarbida is a group of extinct arachnids whose fossil record extends from the late Silurian to the early Permian. These animals are known from several localities in Europe and North America, as well as a single record from Argentina. Trigonotarbids can be envisaged as spider-like arachnids, but without silk-producing spinnerets. They ranged in size from a few millimetres to a few centimetres in body length and had segmented abdomens, with the tergites across the backs of the animals' abdomens, which were characteristically divided into three or five separate plates. Probably living as predators on other arthropods, some later trigonotarbid species were quite heavily armoured and protected themselves with spines and tubercles. About seventy species are currently known, with most fossils originating from the Carboniferous coal measures. In July 2014 scientists used computer graphics to re-create a possible walking gait for the animal.
Rhenanida is an order of scaly placoderms. Unlike most other placoderms, the rhenanids' armor was made up of a mosaic of unfused scales and tubercles. The patterns and components of this "mosaic" correspond to the plates of armor in other, more advanced placoderms, suggesting that the ancestral placoderm had armor made of unfused components, as well.
Drepanopterus is an extinct genus of eurypterid and the only member of the family Drepanopteridae within the Mycteropoidea superfamily. There are currently three species assigned to the genus. The genus has historically included more species, with nine species associated with the genus Drepanopterus, however five of these have since been proven to be synonyms of pre-existing species, assigned to their own genera, or found to be based on insubstantial fossil data. The holotype of one species proved to be a lithic clast.
Elpistostegalia or Panderichthyida is an order of prehistoric lobe-finned fishes which lived during the Late Devonian period. They represent the advanced tetrapodomorph stock, the fishes more closely related to tetrapods than the osteolepiform fishes. The earliest elpistostegalians, combining fishlike and tetrapod-like characters, are sometimes called fishapods, a phrase coined for the advanced elpistostegalian Tiktaalik.
The Columbus Limestone is a mapped bedrock unit consisting primarily of fossiliferous limestone, and it occurs in Ohio, Pennsylvania, and Virginia in the United States, and in Ontario, Canada.
The Helderberg Escarpment also known as Helderberg Mountains is an escarpment and mountain range in eastern New York, roughly 11 miles (18 km) west of the city of Albany. The escarpment rises steeply from the Hudson Valley below, with an elevation difference of approximately 700 feet over a horizontal distance of approximately 2,000 feet. Much of the escarpment is within John Boyd Thacher State Park, and has views of the Hudson Valley and the Albany area.
Densignathus is an extinct genus of early stem-tetrapod from the Late Devonian of Pennsylvania in the United States. A lower jaw has been found from the Red Hill fossil site, which is known for a diversity of lobe-finned fishes and other early tetrapods like Hynerpeton. The type species, Densignathus rowei, was named by paleontologist Douglas Rowe in 2000.
Lechriaspis is an extinct genus of poraspid heterostracan agnathan known from the Early Devonian of northern Utah, western United States.
Gracianella is a genus of fossil brachiopods. It was described by Johnson and Coucot in 1967, and existed from the Silurian to the Devonian of Australia, Austria, Canada, China, the Czech Republic, Italy, Tajikistan, and the United States. A new species, G. paulula, was described by Andrzej Baliński in 2012, from the early Devonian of Ukraine.
Plectodonta is an extinct genus of brachiopods which existed during the Devonian to Silurian of the United States, Australia, Canada, China, the Czech Republic, Czechoslovakia, Germany, Kazakhstan, Morocco, Poland, Spain, Ukraine, Argentina, Bolivia, Sweden, the United Kingdom, and Venezuela. It was described by Kozlowski in 1929, and the type species is P. mariae. A new extinct subspecies, P. mariae pantherae, was described by Andrzej Baliński in 2012, from the early Devonian of Ukraine.
Skenidioides is an extinct genus of brachiopods which existed during the Ordovician, Silurian, and Devonian of what is now Australia, Canada, China, the Czech Republic, Italy, Morocco, Poland, Ukraine, the United States, Belarus, Estonia, Lithuania, Mexico, Norway, Sweden, the United Kingdom, Venezuela, Ireland, Kazakhstan, the Russian Federation, and Argentina. It was described by Schuchert and Cooper in 1931, and the type species is S. billingsi. A new species, S. tatyanae, was described by Andrzej Baliński in 2012, from the early Devonian of Ukraine. The species epithet refers to Tatyana Lvovna Modzalevskaya.
Strophomena is a genus of brachiopods belonging to the order Strophomenida family Strophomenidae, named by Rafinesque in 1824. They were stationary epifaunal suspension feeders.
The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include Haikouichthys. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawed fish. Lampreys belong to the Cyclostomata, which includes the extant hagfish, and this group may have split early on from other agnathans.
Paraspirifer is a genus of large brachiopods that lived during the late Lower and Middle Devonian in what now are Germany, Spain, Morocco and the United States.
Pteraspidiformes is an extinct order of heterostracan agnathan vertebrates known from extensive fossil remains primarily from Early Devonian strata of Europe and North America, and from Upper Silurian Canada.
