Eryops is a genus of extinct, amphibious temnospondyls. It contains the single species Eryops megacephalus, the fossils of which are found mainly in early Permian rocks of the Texas Red Beds, located in Archer County, Texas. Fossils have also been found in late Carboniferous period rocks from New Mexico. Several complete skeletons of Eryops have been found in lower Permian rocks, but skull bones and teeth are its most common fossils.
Otodus megalodon, commonly known as the megalodon, is an extinct species of giant mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. O. megalodon was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark, but has been reclassified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous.
Helicoprion is an extinct genus of shark-like eugeneodont fish. Almost all fossil specimens are of spirally arranged clusters of the individuals' teeth, called "tooth whorls", which in life were embedded in the lower jaw. As with most extinct cartilaginous fish, the skeleton is mostly unknown. Fossils of Helicoprion are known from a 20 million year timespan during the Permian period from the Artinskian stage of the Cisuralian to the Roadian stage of the Guadalupian. The closest living relatives of Helicoprion are the chimaeras, though their relationship is very distant. The unusual tooth arrangement is thought to have been an adaption for feeding on soft bodied prey, and may have functioned as a deshelling mechanism for hard bodied cephalopods such as nautiloids and ammonoids. In 2013, systematic revision of Helicoprion via morphometric analysis of the tooth whorls found only H. davisii, H. bessonowi and H. ergassaminon to be valid, with some of the larger tooth whorls being outliers.
Inostrancevia is an extinct genus of large carnivorous therapsids which lived during the Late Permian in what is now European Russia and South Africa. The first known fossils of this gorgonopsian were discovered in the Northern Dvina, where two almost complete skeletons were exhumed. Subsequently, several other fossil materials were discovered in various oblasts, and these finds will lead to a confusion about the exact number of valid species in the country, before only three of them were officially recognized : I. alexandri, I. latifrons and I. uralensis. More recent research carried out in South Africa has discovered fairly well-preserved remains of the genus, being attributed to the species I. africana. The whole genus is named in honor of Alexander Inostrantsev, professor of Vladimir P. Amalitsky, the paleontologist who described the taxon.
Secodontosaurus is an extinct genus of "pelycosaur" synapsids that lived from between about 285 to 272 million years ago during the Early Permian. Like the well known Dimetrodon, Secodontosaurus is a carnivorous member of the Eupelycosauria family Sphenacodontidae and has a similar tall dorsal sail. However, its skull is long, low, and narrow, with slender jaws that have teeth that are very similar in size and shape—unlike the shorter, deep skull of Dimetrodon, which has large, prominent canine-like teeth in front and smaller slicing teeth further back in its jaws. Its unusual long, narrow jaws suggest that Secodontosaurus may have been specialized for catching fish or for hunting prey that lived or hid in burrows or crevices. Although no complete skeletons are currently known, Secodontosaurus likely ranged from about 2 to 2.7 metres (7–9 ft) in length, weighing up to 110 kilograms (250 lb).
Edestus is an extinct genus of eugeneodontid holocephalian fish known from the Late Carboniferous (Pennsylvanian) of the United Kingdom, Russia, and the United States. Most remains consist of isolated curved blades or "whorls" that are studded with teeth, that in life were situated within the jaws. Edestus is a Greek name derived from the word edeste, in reference to the aberrant quality and size of the species' teeth. The largest species, E. heinrichi, has been conservatively estimated to reach greater than 6.7 m (22 ft) in length, around the size of the largest known great white shark.
Sharks continually shed their teeth; some Carcharhiniformes shed approximately 35,000 teeth in a lifetime, replacing those that fall out. There are four basic types of shark teeth: dense flattened, needle-like, pointed lower with triangular upper, and non-functional. The type of tooth that a shark has depends on its diet and feeding habits.
Sarcoprion is an extinct genus of eugeneodontid holocephalids from the Permian of Greenland. Similar to other eugeneodontids such as Edestus and Helicoprion, it was best known for its extremely bizarre tooth morphology compared to other species of sharks and their closest relatives, the chimaeras. Compared to other members of the Helicoprionidae, its "tooth whorls" were found to be sharper, more compact, and in better condition than other sharks of the time, and refrained from growing to extremely unwieldy forms that would raise questions about its ability to feed properly. The genus contains one species, Sarcoprion edax, found in Permian-aged marine strata of Meddelelser om Grønland.
Ptychodus is a genus of extinct durophagous (shell-crushing) sharks from the Late Cretaceous. Fossils of Ptychodus teeth are found in many Late Cretaceous marine sediments. There are many species among the Ptychodus that have been uncovered on all the continents around the globe. Such species are Ptychodus mortoni, P. decurrens, P. marginalis, P. mammillaris, P. rugosus and P. latissimus to name a few. They died out approximately 85 million years ago. A large number of remains have been found in the former Western Interior Seaway. A 2016 publication found that Ptychodus are likely true sharks belonging to Selachimorpha, rather than hybodonts or batoids as previously thought. Their life history coincides with the typical life of many other large sharks: they lived relatively long lives and were slow growing and produced large offspring and small litters.
Fadenia is an extinct genus of eugeneodontid holocephalian chondrichthyan from the Carboniferous Period of Missouri, the Permian period of Greenland, and the Early Triassic epoch of British Columbia, Canada.
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like chondrichthyans, which existed from the late Devonian to the Late Cretaceous. They form the group of Elasmobranchii closest to neoselachians, the clade of modern sharks and rays. Hybodonts were named and are distinguished based on their conical tooth shape. They are also noted for the presence of a spine on each of their two dorsal fins. They were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct.
The Eugeneodontida, sometimes also called Eugeneodontiformes, is an extinct and poorly known order of cartilaginous fishes. They possessed "tooth-whorls" on the symphysis of either the lower or both jaws and pectoral fins supported by long radials. They probably lacked pelvic fins and anal fins. The palatoquadrate was either fused to the skull or reduced. Now determined to be within the Holocephali, their closest living relatives are ratfish. The eugeneodonts are named after paleontologist Eugene S. Richardson, Jr. The Eugeneodontida disappeared in the Early Triassic. The geologically youngest fossils of the group are known from the Sulphur Mountain Formation, Vardebukta Formation and Wordie Creek Formation (Greenland).
Helicoprionidae is an extinct, poorly known family of bizarre holocephalids within the poorly understood order Eugeneodontida. Members of the Helicoprionidae possessed a unique "tooth-whorl" on the symphysis of the lower jaw and pectoral fins supported by long radials. The closest living relatives of the Helicoprionidae and all other eugeneodontids are the ratfishes. The anatomy of the tooth-whorl differed amongst genus and species, some possessing complete spirals, others possessing halved spirals, and some with wedged half-spirals. Each tooth-whorl is thought to be adapted to a different type of prey, and a different predation strategy.
The Edestidae are a poorly known, extinct family of shark-like eugeneodontid holocephalid cartilaginous fish.
Scaldicetus is an extinct genus of highly predatory macroraptorial sperm whale. Although widely used for a number of extinct physeterids with primitive dental morphology consisting of enameled teeth, Scaldicetus as generally recognized appears to be a wastebasket taxon filled with more-or-less unrelated primitive sperm whales.
Toxoprion is an extinct genus of eugeneodont holocephalids whose fossils are found in marine strata from the Early Carboniferous until the Late Permian near Eureka, Nevada.
Cosmopolitodus is an extinct genus of mackerel shark that lived between thirty and one million years ago during the late Oligocene to the Early Pleistocene epochs. Its type species is Cosmopolitodus hastalis, the broad-tooth mako. In 2021, Isurus planus was reassigned to the genus, and thus became the second species C. planus.
Cladodont is the term for a common category of early Devonian shark known primarily for its "multi-cusped" tooth consisting of one long blade surrounded by many short, fork-like tines, designed to catch food that was swallowed whole, instead of being used to saw off chunks of meat like many modern sharks. The skinny teeth would puncture and grasp the prey, keeping it from wriggling free.
Qianodus is a jawed vertebrate genus that is based on disarticulated teeth from the lower Silurian of China. The type and only species of Qianodus, Q. duplicis, is known from compound dental elements called tooth whorls, each consisting of multiple tooth generations carried by a spiral-shaped base. The tooth whorls of Qianodus represent the oldest unequivocal remains of a toothed vertebrate, predating previously recorded occurrences by about 14 million years. The specimens attributed to the genus come from limestone conglomerate beds of the Rongxi Formation exposed near the village of Leijiatun, Guizhou Province, China. These horizons have been interpreted as tidal deposits1 that form part of the shallow marine sequences of the Rongxi Formation.
Campyloprion is an extinct genus of large shark-like eugenodont fish. Two species of Campyloprion are known, C. annectans from Texas and New Mexico in United States and C. ivanovi from Russia. The fossils date to the Gzhelian stage, approximately 303.4–298.9 million years ago. There is a small gap in age between the latest Edestus and the first Campyloprion, which suggests that Campyloprion might have evolved to fit into an ecological niche left vacant by the extinction of Edestus. The fact that Campyloprion is older than Helicoprion suggests, but does not prove, that it is a direct ancestor of Helicoprion.
