Devonian extinctions

Placoderms (from Ancient Greek πλάξ [plax, plakos] 'plate' and δέρμα [derma] 'skin') are vertebrate animals of the class Placodermi, an extinct group of prehistoric fish known from Paleozoic fossils during the Silurian and the Devonian periods. While their endoskeletons are mainly cartilaginous, their head and thorax were covered by articulated armoured plates (hence the name), and the rest of the body was scaled or naked depending on the species.

Cephalaspidomorphi (alternatively called Monirhina, or simply cephalaspids) is a class of jawless fishes that is presently regarded as uniting the osteostracans, galeaspids and pituriaspids. Most biologists regard this taxon as extinct, but the name is still sometimes used in the classification of lampreys because they were once thought to be descended. If lampreys are included they would extend the known range of the group from the Silurian and Devonian periods, when they are traditionally assumed to have lived, to the present day. Modern works typically assume the cephalaspidimorphs to be th

Cystoidea was defined as a class of extinct paleozoic blastozoan echinoderms established to encompass stalked taxa that were neither crinoids nor blastoids. It was shown to be polyphyletic in the late 1960s but continues to be used even in recent (as of 2022) literature to discuss both rhombiferans and diploporitans.

The zosterophylls are a group of extinct land plants that first appeared in the Silurian period. The taxon was first established by Banks in 1968 as the subdivision Zosterophyllophytina; they have since also been treated as the division Zosterophyllophyta or Zosterophyta and the class or plesion Zosterophyllopsida or Zosteropsida. They were among the first vascular plants in the fossil record, and had a world-wide distribution. They were probably stem-group lycophytes, forming a sister group to the ancestors of the living lycophytes. By the late Silurian (late Ludlovian, about ) a diverse asse

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.

Carcinosomatidae (the name deriving from the type genus Carcinosoma, meaning "crab body") is a family of eurypterids, an extinct group of aquatic arthropods. They were members of the superfamily Carcinosomatoidea, also named after Carcinosoma. Fossils of carcinosomatids have been found in North America, Africa, Europe and Asia, the family possibly having achieved a worldwide distribution, and range in age from the Early Ordovician to the Early Devonian. They were among the most marine eurypterids, known almost entirely from marine environments.

Linguliformea is a subphylum of inarticulate brachiopods. These were the earliest of brachiopods, ranging from the Cambrian into the Holocene. They rapidly diversified during the Cambrian into the Ordovician, but most families became extinct by the end of the Devonian.

Zosterophyllum was a genus of Silurian-Devonian vascular land plants with naked branching axes on which usually kidney-shaped sporangia were arranged in lateral positions. It is the type genus for the group known as zosterophylls, thought to be part of the lineage from which modern lycophytes evolved. More than 20 species have been described.

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.

Osteolepididae is a family of primitive, fish-like tetrapodomorphs (the clade that contains modern tetrapods and their extinct relatives) that lived during the Devonian period. The family is generally thought to be paraphyletic, with the traits that characterise the family being widely distributed among basal tetrapodomorphs and other osteichthyans. Some of the genera historically placed in Osteolepididae have more recently been assigned to the family Megalichthyidae, which appears to be a monophyletic group.

Dolichopteridae is an extinct family of eurypterids that lived in the Silurian and Devonian periods.

The Hardieopteridae are a family of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". The family is one of two families contained in the superfamily Kokomopteroidea (along with Kokomopteridae), which in turn is one of four superfamilies classified as part of the suborder Stylonurina. Hardieopterids have been recovered from deposits of Early Silurian to Late Devonian age in the United States, the United Kingdom, and Belgium.

Loganellia is a genus of jawless fish which lived between 430 and 370 million years ago, during the Silurian and Devonian periods of the Paleozoic. Loganellia belonged to the Thelodonti class and like other thelodonts possessed scales instead of plate armor.

Dalmanitidae is a family of trilobites in the order Phacopida that lived from the Floian (Ordovician) to the Devonian and includes 33 genera.

Ozarkodina is an extinct genus of conodonts in the family Spathognathodontidae.

Michelinoceras is the oldest known genus of the Michelinocerida, more commonly known as the Orthocerida, characterized by long, slender, nearly cylindrical orthocones with a circular cross section, long camerae, very long body chambers, and a central or near central tubular siphuncle free of organic deposits. Septal necks are straight; connecting rings cylindrical and thin. Cameral deposits are well developed. A radula has been found in one species, with seven teeth per row. It had ten arms, two of which formed longer tentacles.

The Tarphycerida were the first of the coiled cephalopods, found in marine sediments from the Lower Ordovician (middle and upper Canad) to the Middle Devonian. Some, such as Aphetoceras and Estonioceras, are loosely coiled and gyroconic; others, such as Campbelloceras, Tarphyceras, and Trocholites, are tightly coiled, but evolute with all whorls showing. The body chamber of tarphycerids is typically long and tubular, as much as half the length of the containing whorl in most, greater than in the Silurian Ophidioceratidae. The Tarphycerida evolved from the elongated, compressed, exogastric Bas

Erieopterus is a genus of prehistoric eurypterid found in Silurian to Devonian-aged marine and freshwater strata of North America. The genus contains three species from the Silurian to the Devonian.'''''''' Erieopterus'' is the only genus in the family Erieopteridae, part of the Dolichopteroidea superfamily.

Kokomopteroidea is an extinct superfamily of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". It is one of four superfamilies classified as part of the suborder Stylonurina. Kokomopteroids have been recovered from deposits of Early Silurian to Late Devonian age in the United States and the United Kingdom.

The Actinocerida are an order of generally straight, medium to large cephalopods that lived during the early and middle Paleozoic, distinguished by a siphuncle composed of expanded segments that extend into the adjacent chambers, in which deposits formed within contain a system of radial canals and a narrow space along the inner side of the connecting ring known as a paraspatium. (Teichert 1964) Septal necks are generally short and cyrtochoanitic, some being recumbent, some hook shaped. Most grew to lengths of about but some, like the Huroniidae of the Silurian grew significantly larger.