Edaphodon Temporal range: | |
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Tooth plates of E. mirificus, American Museum of Natural History | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Holocephali |
Order: | Chimaeriformes |
Family: | Callorhinchidae |
Genus: | † Edaphodon Buckland, 1838 |
Type species | |
Edaphodon bucklandii Agassiz, 1843 | |
Species | |
See text |
Edaphodon was a fish genus of the family Callorhinchidae (sometimes assigned to Edaphodontidae). As a member of the Chimaeriformes, Edaphodon was a type of rabbitfish, a cartilaginous fish related to sharks and rays. The genus appeared in the Aptian age of the Lower Cretaceous and vanished in the Pliocene. [1] It was most prominent during the Late Cretaceous. Many Edaphodon species were found in the Northern Hemisphere, but species from the Southern Hemisphere are also known (e.g., E. kawai from New Zealand and E. snowhillensis from Antarctica). [2]
Like most other chimaeriforms, Edaphodon is known mainly from poorly preserved specimens because its skeleton was made of cartilage. So, in most cases, only tooth plates and fin spines have been preserved, and they are also often dissociated. [3] Like other chimaeriforms, it fed using six pairs of tooth plates—one pair on the lower jaw (mandibular) and two pairs on the upper (vomerine and palatine), which bear tooth-like hypermineralized areas known as tritors. The patterning of the tritors is used to distinguish chimaeriforms. In Edaphodon, the vomerine tooth plates are covered in rod-like tritors; each palatine tooth plate is massive, and has one large tritor on the outer edge and two large tritor pads and one small tritor pad in the middle; and each mandibular tooth plate is massive and has a beak-like tritor at the front end, along with two pairs of tritor pads at their outer edges and a single large tritor pad in the middle. [2]
The closest relative of Edaphodon was Ischyodus. They were generally similar, but Ischyodus had four large tritor pads on its palatine tooth plates, as well as thinner mandibular tooth plates with shorter beaks. [4] Edaphodon would have used its tritors for both crushing hard-shelled and slicing other prey such as fishes, sharks, and marine reptiles. [5] In the Upper Cretaceous of Alabama, where I. bifurcatus, E. barberi, and E. mirificus coexisted, the two genera may have had different diets, with Ischyodus feeding on more hard-shelled prey. [4]
Externally, Edaphodon would have been similar to other rabbitfish in appearance. However, at least some species of Edaphodon would have been far larger. The largest mandibular tooth plates of the living Callorhinchus measure 20–50 millimetres (0.79–1.97 in) in length; the largest E. sedgwickii mandibular tooth plates reach 225 millimetres (8.9 in), and E. snowhillensis mandibular tooth plates also reached 180 millimetres (7.1 in). [2] According to living callorhynchid and rhinochimaerid specimens, palatine plate represents 4 percent of the length between gill opening and body tip excluding elongated tail. [4] Based on this calculation, the species E. barberi, E. mirificus, and E. snowhillensis have been estimated at over 3 metres (9.8 ft) in length, [2] with one individual of E. mirificus reaching 3.43 metres (11.3 ft). [4]
Edaphodon has numerous species, all of which are extinct. They include: [2] [6] [7]
Species of questionable validity include: [6]
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
Cow sharks are a shark family, the Hexanchidae, characterized by an additional pair or pairs of gill slits. Its 37 species are placed within the 10 genera: Gladioserratus, Heptranchias, Hexanchus, Notidanodon, Notorynchus, Pachyhexanchus, Paraheptranchias, Pseudonotidanus, Welcommia, and Weltonia.
Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks, rays, skates, and sawfish. Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil.
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Edaphodon kawai was a prehistoric chimaeriform fish species belonging to the genus Edaphodon, of which all the species are now extinct. Edaphodon kawai was a type of rabbitfish, a cartilaginous fish related to sharks and rays, and indeed, some rabbitfishes are still alive today. E. kawai is one of numerous Edaphodon species, but is the only one which has been discovered in the Southern Hemisphere, near New Zealand. Indeed, only a handful of other Chimaeroformes have been discovered in the Southern Hemisphere. They first appeared during the Devonian period around 415 to 360 million years ago, but the only known specimen of E. kawai has been dated to the Late Cretaceous at the height of the rabbitfish's reign. Its scientific name, kawai, means "fish" in the language of the Moriori, a Pacific tribe who inhabited the islands.
Symmoriiformes is an extinct order of stem-group holocephalians. Originally named Symmoriida by Zangerl (1981), it has subsequently been known by several other names. Lund (1986) synonymized the group with Cladodontida, while Maisey (2008) corrected the name to Symmoriiformes in order to prevent it from being mistaken for a family. The symmoriiform fossils record begins during the late Devonian. Most of them died out at the start of the Permian, but Dwykaselachus is known from the Artinskian-Kungurian of South Africa. Teeth described from the Valanginian of France and Austria indicate that members of the family Falcatidae might have survived until the Early Cretaceous; however, these teeth were also argued to be more likely neoselachian teeth.
Hydrolagus is a genus of fish in the family Chimaeridae found in the Atlantic, Indian and Pacific Oceans.
Ptychodus is a genus of extinct large durophagous (shell-crushing) lamniform sharks from the Cretaceous period, spanning from the Albian to the Campanian. Fossils of Ptychodus teeth are found in many Late Cretaceous marine sediments worldwide.
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Squaloraja is an extinct genus of bizarre ray-like marine chimaeriform fish from the Early Jurassic of Europe.
The Snow Hill Island Formation is an Early Maastrichtian geologic formation found on James Ross Island, James Ross Island group, Antarctica. Remains of a paravian theropod Imperobator antarcticus have been recovered from it, as well as the elasmarian ornithopods Trinisaura santamartaensis, Biscoveosaurus and Morrosaurus antarcticus, the ankylosaurian Antarctopelta oliveroi, and the shark Notidanodon sp. Alongside these described genera are also the remains of indeterminate elasmosaurids, lithostrotian titanosaurs and an indeterminate pterosaur.
The New Egypt Formation is a Late Cretaceous (Maastrichtian) geologic formation of the Monmouth Group in New Jersey, United States.
This list of fossil fishes described in 2015 is a list of new taxa of jawless vertebrates, placoderms, acanthodians, fossil cartilaginous fishes, bony fishes and other fishes of every kind that have been described during the year 2015, as well as other significant discoveries and events related to paleontology of fishes that occurred in the year 2015. The list only includes taxa at the level of genus or species.
Ornithoprion is a monotypic genus of extinct eugeneodont holocephalan in the family Caseodontidae. The type and only species, O. hertwigi, lived during the Moscovian stage of the Carboniferous, between 315.2 to 307 million years ago, and is known from black shale deposits in what is now the Midwestern United States. The discovery and description of Ornithoprion, performed primarily via radiography, helped clarify the cranial anatomy of the eugeneodonts, a group which were previously known primarily from isolated tooth whorls. The genus derives its name from the elongate, bill-like rostrum and large eyes, which vaguely resemble the features of a bird, while the species name honors Oscar Hertwig. It is known from specimens preserving the skull and anterior portion of the body.
Ptyctodus is an extinct armour-plated fish of the late Devonian. Ptyctodus belongs to the family Ptyctodontidae and is of the class Placodermi. They share a close resemblance to modern day chimaeras (Holocephali). Fossils of this armour-plated fish have been found in locations such as in Russia, the Michigan Basis, and Arizona, United States.
Amylodon is an extinct genus of chimaera. It consists of four described species. A. karamysh is known from the latest early Campanian of Russia, the name being derived from the Karamysh River which runs near the type locality. In the Eocene, two species are known. A. venablesae and A. eocenica are both known from the Ypresian-aged London Clay of England. A mandibular plate originally ascribed to the latter was found in the Bartonian of the Barton Beds of England, though later found not to fit with any described species. A. delheidi is known from the Rupelian-aged Boom Clay of Belgium. All species are known mainly from isolated mandibles. They show a slow progressing towards increased shearing ability. Amylodon was considered to be a member of Chimaeridae in Nessov and Averianov, 1996 but other studies have either been assigned to the "Edaphodontidae", or to the Rhinochimaeridae.
Pachymylus is an extinct genus of chimaera belonging to the family Callorhinchidae. The type species. P. leedsi was described by A. S. Woodward in 1892, and is known from the Middle-Late Jurassic (Callovian-Oxfordian) Oxford Clay of Peterborough, England. The type material consisted of a large mandibular tooth and two palatine teeth. Indeterminate remains of the genus are also known from the Middle Jurassic (Bajocian) of France.
Agassizilia is an extinct genus of both freshwater and marine pycnodont fishes from the mid-late Cretaceous. The genus is named after paleontologist Louis Agassiz.