Mawsonia | |
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Skeleton of Mawsonia gigas, showing estimated size of largest known individual | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Sarcopterygii |
Class: | Actinistia |
Order: | Coelacanthiformes |
Family: | † Mawsoniidae |
Genus: | † Mawsonia Woodward, 1907 |
Type species | |
†Mawsonia gigas Woodward, 1907 | |
Species | |
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Mawsonia is an extinct genus of prehistoric coelacanth fish. It is amongst the largest of all coelacanths, with one quadrate specimen (DGM 1.048-P) possibly belonging to an individual measuring 5.3 metres (17.4 feet) in length. [2] It lived in freshwater and brackish environments from the late Jurassic to the mid-Cretaceous (Kimmeridgian to Cenomanian stages, about 152 to 96 million years ago) of South America, eastern North America, and Africa. Mawsonia was first described by British paleontologist Arthur Smith Woodward in 1907. [3]
The fish has six fins: two on the top of the body, two on the sides, one at the end of its tail and one at the bottom of its tail. Rather than having teeth, the inside of the mouth was covered in small (1-2 mm) denticles. [1] It reached at least 3.5 m (11 ft) in length, although one specimen possibly exceeded 5 m (16 ft), only rivaled by the related Trachymetopon. [4] [5] [2]
The genus was named by Arthur Smith Woodward in 1907, from specimens found in the Early Cretaceous (Hauterivian) aged Ilhas Group of Bahia, Brazil.
Fossils have been found on three continents; in South America they have been found in the Bahia Group, Romualdo, Alcântara, Brejo Santo and Missão Velha Formations of Brazil, and the Tacuarembó Formation of Uruguay. [1] In Africa, they are known from the Continental Intercalaire of Algeria and Tunisia, the Ain el Guettar Formation of Tunisia, the Kem Kem Group of Morocco, and the Babouri Figuil Basin of Cameroon, spanning from the Late Jurassic, to early Late Cretaceous. Fossils assigned to Mawsonia have also been found in Woodbine Formation of Texas, USA, then part of the island continent Appalachia. [6] [7]
The type species is Mawsonia gigas, named and described in 1907. Numerous distinct species have been described since then. M. brasiliensis, M. libyca, M. minor, and M. ubangiensis have all been proposed to be synonyms of M. gigas, [5] [8] although Léo Fragoso's 2014 thesis on mawsoniids [9] finds M. brasiliensis valid and cautions against synonymizing M. minor without further examination. Several recent publications consider M. brasiliensis to be valid as well. [8] [10] [11] [12] Although initially considered to belong to this genus, "Mawsonia" lavocati is most likely referable to Axelrodichthys instead. [12] [13]
Mawsonia was native to freshwater and brackish ecosystems. [14] The diet of Mawsonia and their mechanism of feeding is uncertain. It has been suggested that the denticles were used to crush hard shelled organisms (durophagy) [15] or that prey was swallowed whole using suction feeding. [16]
Coelacanths are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. As sarcopterygians, they are more closely related to lungfish and tetrapods than to ray-finned fish.
Macropoma is an extinct genus of coelacanth in the class Sarcopterygii. Fossils of Macropoma have been found in both England and Czech Republic, dating to the mid-Cretaceous (Albian-Turonian). Recorded fossils have bodies under two feet in length. A modern coelacanth measures five or more, but in other respects the two genera are remarkably similar, and share the same body plan with a three-lobed tail and stalked fins.
Chinlea is an extinct genus of late Triassic Mawsoniid coelacanth fish found in and named after the Chinle Formation that crops out in the southwestern states of Arizona and New Mexico. The word “Chinle” comes from the Navajo word meaning "flowing out", referencing the location where water flows out of the Canyon de Chelly. They were also possibly found in the Dockum Group.
Latimeriidae is the only extant family of coelacanths, an ancient lineage of lobe-finned fish. It contains two extant species in the genus Latimeria, found in deep waters off the coasts of southern Africa and east-central Indonesia. In addition, several fossil genera are known from the Mesozoic of Europe, the Middle East, and the southeastern United States, dating back to the Triassic.
Axelrodichthys is an extinct genus of mawsoniid coelacanth from the Cretaceous of Africa, North and South America, and Europe. Several species are known, the remains of which were discovered in the Lower Cretaceous (Aptian-Albian) of Brazil, North Africa, and possibly Mexico, as well as in the Upper Cretaceous of Morocco (Cenomanian), Madagascar and France. The Axelrodichthys of the Lower Cretaceous frequented both brackish and coastal marine waters while the most recent species lived exclusively in fresh waters. The French specimens are the last known fresh water coelacanths. Most of the species of this genus reached 1 metre to 2 metres in length. Axelrodichthys was named in 1986 by John G. Maisey in honor of the American ichthyologist Herbert R. Axelrod.
Coccoderma is an extinct genus of prehistoric marine coelacanth which lived during the Late Jurassic period. Fossils have been found in Germany and France. It was small in size, about 27.5 cm. They had very long and sharp teeth.
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.
Whiteia is an extinct genus of prehistoric coelacanth fish which lived during the Triassic period. It is named after Errol White.
Laugiidae is an extinct family of prehistoric marine coelacanths which lived during the Triassic and Jurassic periods. Their fossils have been found in Canada, Germany and Greenland.
The Kem Kem Group is a geological group in the Kem Kem region of eastern Morocco, whose strata date back to the Cenomanian stage of the Late Cretaceous. Its strata are subdivided into two geological formations, with the lower Ifezouane Formation and the upper Aoufous Formation used for the strata on the eastern side of the Atlas Mountains (Tinghir), with the Gara Sbaa Formation and Douira Formation used in the southern Tafilalt region. It is exposed on an escarpment along the Algeria–Morocco border.
Lualabaea is an extinct genus of prehistoric freshwater coelacanth, belonging to the family Mawsoniidae, from the Jurassic period. It contains two species, L. lericheiSaint-Seine, 1955 and L. henryiSaint-Seine, 1955, both known from the Stanleyville Formation of the Democratic Republic of the Congo. It may be related to or possibly synonymous with Axelrodichthys.
Swenzia is an extinct genus of coelacanthid fish from the late Jurassic of France. It contains a single species, S. latimerae, which was originally described as Wenzia latimerae. Because the generic name Wenzia was already preoccupied by a snail, the generic name was amended to Swenzia. It is the fossil genus most closely related to the living coelacanth, Latimeria.
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.
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 metres (11–15 ft) in length.
Parnaibaia is a genus of coelacanth fish which lived during the Late Jurassic period. Parnaibaia fossils have been found in the Pastos Bons Formation in Maranhão, Brazil. Parnaibaia was described for the first time by palaeontologist Yoshitaka Yabumoto in 2008.
Foreyia is an extinct genus of coelacanth lobe-finned fish which lived during the Middle Triassic period in what is now Canton of Graubünden, Switzerland. It contains a single species F. maxkuhni.
This list of fossil fishes described in 2019 is a list of new taxa of jawless vertebrates, placoderms, acanthodians, fossil cartilaginous fishes, bony fishes, and other fishes of every kind that were described during the year 2019, as well as other significant discoveries and events related to paleoichthyology that occurred in 2019.
The Pastos Bons Formation is a Late Jurassic geologic formation of the Parnaíba Basin in Maranhão, northeastern Brazil. The formation forms part of the sag phase of the basin. It overlies the Sardinha Formation and is overlain by the Mosquito Formation. The fluvial to lacustrine sandstones and shales have provided fossils of a coelacanth fish, Parnaibaia maranhaoensis and a paralligatorid named after the formation, Batrachomimus pastosbonensis.
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.
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