| Undina Temporal range: Triassic-Cretaceous | |
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| Undina penicillata, at Göteborgs Naturhistoriska Museum | |
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| Genus: | Undina Münster, 1834 |
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†Holophagus Egerton 1861 | |
Undina is a genus of prehistoric coelacanth, lobe-finned fish, which lived from the Triassic period to the Cretaceous period.
Species of this genus have been found in Cretaceous of Spain, in Jurassic of Germany, Turkey and the United Kingdom and in Triassic of Italy.
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The Jurassic is a geologic period and stratigraphic system that spanned from the end of the Triassic Period 201.4 million years ago (Mya) to the beginning of the Cretaceous Period, approximately 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified.
The Mesozoic Era is the second-to-last era of Earth's geological history, lasting from about 252 to 66 million years ago, comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of gymnosperms and of archosaurian reptiles, such as the dinosaurs; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic.
Mesolimulus is an extinct genus of horseshoe crab. The best known examples are found in Solnhofen limestone near Solnhofen, Bavaria, Germany. Originally assigned to the living genus Limulus, they are related to and look virtually identical to modern horseshoe crabs. Other species assigned to Mesolimulus have been recorded spanning over 140 million years from the Middle Triassic to Late Cretaceous from England, Spain, Siberia and Morocco.
Diplurus is a genus of prehistoric mawsoniid coelacanth fish which lived during the Late Triassic-Early Jurassic period in North America. The fossils of this genus are common on the eastern North American Margin, being a key taxon of the Newark Supergroup, and recovered from units such as the Bull Run Formation, Lockatong Formation, Stockton Formation, Solite Quarry, Midland Formation, East Berlin Formation, Boonton Formation and the Portland Formation. Three species are know, the type D. longicaudatus, the youngest and biggest, D. newarki, the oldest, followed then by "D. uddeni" (Eastman), also from older rocks and considered dubious. A recent work has recovered a 3rd or 4th species, D. enigmaticus, from the Late Triassic of New Jersey, representing another small-bodied form living in sympatry with the similarly sized D. newarki. This genus ranges in size from 15 cm of D. newarki and D. enigmaticus in New Jersey to the larger 60 cm specimens of Diplurus longicaudatus found in the Connecticut River Valley, which indicates a considerable growth and likely a changue in the ecological position of the genus to a possible apex predatory niche.
Laugia is an extinct genus of coelacanth fish which lived during the Induan age of the Early Triassic epoch in what is now Greenland. The type and only species, Laugia groenlandica, was collected from the Wordie Creek Formation and described by Erik Stensiö. The genus is named after Lauge Koch.
Libys is a genus of coelacanth fish in the family of Latimeridae. Species of Libys lived during the Upper Jurassic period.
Ticinepomis is an extinct genus of coelacanth lobe-finned fish which lived during the Middle Triassic period in what is now Switzerland. It contains two species, T. peyeri and T. ducanensis.
Holophagus is an extinct genus of coelacanth belonging to Latimeriidae. The type species, Holophagus gulo, is known from the Lower Jurassic marine Lias of England. Some authors have considered the genus restricted to the Lias of England.
Mawsoniidae is an extinct family of prehistoric coelacanth fishes which lived during the Triassic to Cretaceous periods. Members of the family are distinguished from their sister group, the Latimeriidae by the presence of ossified ribs, a coarse rugose texture on the dermatocranium and cheek bones, the absence of the suboperculum and the spiracular, and reduction or loss of the descending process of the supratemporal. Mawsoniids are known from North America, Europe, South America, Africa, Madagascar and Asia. Unlike Latimeriidae, which are exclusively marine, Mawsoniidae were also native to freshwater and brackish environments. Mawsoniids represent among the youngest known coelacanths, with the youngest known remains of the freshwater genus Axelrodichthys from France and an indeterminate marine species from Morocco being from the final stage of the Cretaceous, the Maastrichtian, roughly equivalent in age to the youngest known fossils of latimeriids. Species of Mawsonia and Trachymetopon are known to have exceeded 5 metres in length, making them among the largest known bony fish to have ever existed.
Trachymetopon is an extinct genus of prehistoric coelacanth from the Jurassic of Europe. Fossils have been found in the Early Jurassic Posidonia Shale of Germany the Middle Jurassic Marnes de Dives of France, and probably the Late Jurassic Kimmeridge Clay of England. Only one species has been named, Trachymetopon liassicum, described by Henning in 1951 from an almost complete specimen found in the Lower Toarcian of Ohmden in Baden-Württemberg. Another specimen is known from the same site, and two older specimens come from the Sinemurian of Holzmaden. The holotype of this species is 1.6 metres in length. A giant specimen of an undetermined species of Trachymetopon found at the Middle Jurassic Falaises des Vaches Noires of Normandy. This specimen, composed of a 53 cm long palatoquadrate, belongs to an individual 4 metres (13 ft) in length. A basisphenoid found in a museum in Switzerland that likely originates from the same locaity probably belonged to an individual around 5 m (16 ft) long, making Trachymetopon the largest of all coelacanths alongside Mawsonia. A study published in 2015 revealed that this coelacanth belongs to the Mawsoniidae. Trachymetopon is one of the few known mawsoniids to have been exclusively marine, while most of the other members of the group have lived in fresh and brackish waters.
Coccolepis is an extinct genus of prehistoric ray-finned fish in the family Coccolepididae. Originally including most species within the family, it is now restricted to two species from the Late Jurassic Solnhofen Limestone of Germany. The holotype of C. bucklandi, designated and described by Louis Agassiz, was thought to be lost but was later rediscovered in Neuchâtel.
The Ommatidae are a family of beetles in the suborder Archostemata. The Ommatidae are considered the extant beetle family that has most ancestral characteristics. There are only seven extant species, confined to Australia and South America. However, the geographical distribution was much wider during the Mesozoic spanning across Eurasia and Australia, suggesting that they were widespread on Pangea. So far, over 26 extinct genera containing over 170 species of these beetles have been described. Three extant genera have been assigned to this family: Omma,Tetraphalerus and Beutelius. The family is considered to be a subfamily of Cupedidae by some authors, but have been found to be more closely related to Micromalthidae in molecular phylogenies. A close relationship with Micromalthidae is supported by several morphological characters, including those of the mandibles and male genitalia. Due to their rarity, their ecology is obscure, it is likely that their larvae feed on deadwood.
Stenophlebia is an extinct genus of dragon-damselfly from late Jurassic and early Cretaceous period.
Palaeontinidae, commonly known as giant cicadas, is an extinct family of cicadomorphs. They existed from the Late Triassic to the Early Cretaceous. The family contains around 30 to 40 genera and around a hundred species.
Omma is a genus of beetles in the family Ommatidae. Omma is an example of a living fossil. The oldest species known, O. liassicum, lived during the final stage of the Triassic (Rhaetian), over 200 million years ago, though the placement of this species in Omma has been questioned. Numerous other fossil species are known from the Jurassic and Cretaceous of Europe and Asia. The only living species is Omma stanleyi, which is endemic to Australia. Three other extant species endemic to Australia that were formerly part of this genus were moved to the separate genus Beutelius in 2020.Omma stanleyi is strongly associated with wood, being found under Eucalyptus bark and exhibiting thanatosis when disturbed. Its larval stage and many other life details are unknown due to its rarity. Males are typically 14–20 mm in length, while females are 14.4-27.5 mm. Omma stanleyi occurs throughout eastern Australia from Victoria to Central Queensland.
Chresmodidae is an extinct family of Mesozoic insects within the superorder Polyneoptera.
Megalocoelacanthus dobiei is an extinct species of giant latimeriid coelacanth lobe-finned fish which lived during the Lower Campanian epoch until possibly the early Maastrichtian in the Late Cretaceous period in Appalachia, the Western Interior Seaway and Mississippi Embayment. Its disarticulated remains have been recovered from the Eutaw Formation, Mooreville Chalk Formation, and Blufftown Formation of Alabama, Mississippi, and Georgia, and also from the Niobrara Formation of Kansas. Although no complete skeleton is known, careful examination of skeletal elements demonstrate it is closely related to the Jurassic-aged coelacanthid Libys. The species is named for herpetologist James L. Dobie. It has been estimated to have been 3.5—4.5 meters in length.
Asteracanthus is an extinct genus of hybodont, known from the Middle Jurassic (Bathonian) to the Early Cretaceous (Valanginian).
This list of fossil fish research presented in 2021 is a list of new taxa of jawless vertebrates, placoderms, acanthodians, fossil cartilaginous fishes, bony fishes, and other fishes that were described during the year, as well as other significant discoveries and events related to paleoichthyology that occurred in 2021.
Coccolepididae is an extinct family of ray-finned fish, known from the Early Jurassic to Early Cretaceous, most of which were originally referred to the type genus Coccolepis. They had a widespread distribution, being found in North and South America, Australia, Asia and Europe. They are mostly known from freshwater environments, though several species have been found in marine environments. They are morphologically conservative, and have poorly ossified endo and exoskeletons, which usually results in poor preservation. This makes it difficult to distinguish species. They are generally small fish, with the largest known specimens reaching a length of 210 mm. Historically, they have been classified as members of “Palaeonisciformes”, a paraphyletic grouping of non-neopterygian fish, due to their plesiomorphic conservative morphology closely resembling those of many other groups of primitive fish. They have been suggested to be relatives of the Acipenseriformes within the Chondrostei.
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