Halosaurs are eel-shaped fishes found only at great ocean depths. As the family Halosauridae, halosaurs are one of two families within the order Notacanthiformes; the other being the deep-sea spiny eels, Notacanthidae. Halosaurs are thought to have a worldwide distribution, with some 17 species in three genera represented. Only a handful of specimens have been observed alive, all in chance encounters with Remotely operated underwater vehicles.
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last two names are also applied to Opisthoproctidae and Siganidae, respectively.
Placoderms 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, and the rest of the body was scaled or naked depending on the species.
Cladoselache is an extinct genus of shark-like chondrichthyan from the Late Devonian (Famennian) of North America. It was similar in body shape to modern lamnid sharks, but was not closely related to lamnids or to any other modern (selachian) shark. As an early chondrichthyan, it had yet to evolve traits of modern sharks such as accelerated tooth replacement, a loose jaw suspension, enameloid teeth, and possibly claspers.
This glossary of ichthyology is a list of definitions of terms and concepts used in ichthyology, the study of fishes.
The lesser sand eel or sand lance is a species of fish in the sand lance family Ammodytidae. It is an elongated cylindrical fish which may be up to 20 centimetres (7.9 in) long.
The great sand eel is the greater species of sand eel. The maximum size is 35 centimetres (14 in).
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 midline of the upper and lower 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, possibly making it the largest marine predator to have ever existed up to that point.
The saddled swellshark is a rare species of catshark, and part of the family Scyliorhinidae, endemic to Eastern Australia. This bottom-dwelling species is found on the outer continental shelf and upper continental slope at a depth of 115–605 m (377–1,985 ft). It is a robustly built shark with a short, broad, flattened head and a capacious mouth. Adults are patterned with saddles on a brownish or grayish background, which varies between tropical and temperate sharks; juveniles are light-colored with many spots. This shark reaches 74 cm (29 in) in length. Like other swellsharks, it can inflate itself as a defensive measure. Reproduction is oviparous.
The narrowbar swellshark is a rare species of catshark, and part of the family Scyliorhinidae, known only from two specimens collected near Flinders Reef off northeastern Australia. This species reaches at least 44.5 cm (17.5 in) in length, and has a stocky body with a short, broad head. It can be readily identified by its zebra-like dorsal color pattern of transverse brown bars on a yellowish background. Like other swellsharks, it can inflate its body as a defensive measure.
The silver chimaera, or ginzame, is a species of holocephalan in the family Chimaeridae. They are found in the deep sea along the coast of East Asia, from Japan to Indonesia. They are chondrichthyans, closely related to sharks and rays, which means that they have a fully cartilaginous skeleton with no true bones.
Harpagofututor is an extinct genus of eel-like cartilaginous fish from the Early Carboniferous (Mississippian) Bear Gulch Limestone of Montana in North America.
Echinochimaera is an extinct genus of chimaeriform fish, known from the Lower Carboniferous Bear Gulch Limestone in Montana, United States. It is one of the earliest Chimaeriformes known.
Chondrenchelys is an extinct genus of cartilaginous fish and the earliest member of Holocephali known from complete skeletons. Chondrenchelys would have been quite a relatively medium-sized fish with an elongated body up to 18 cm (0.59 ft)in length, it had a dorsal fin which was indeed long and a body which tapered to a point. Chondrenchelys had one large pair, one middle-sized pair, and three small pair of tooth plates in each jaw. The genus name derives from the Greek word χόνδρος, meaning “gristle” or “cartilage”, and ἔγχελυς, meaning “eel”. The speciea name, problematicus, is likely derived from the lack of scales setting it apart from all other fish known at the time of discovery.
Iniopterygiformes is an extinct order of cartilaginous fish known only from the Carboniferous period of the United States. Iniopterygians are characterized by large, superficially wing-like pectoral fins positioned upwards behind the head, from which the name of the group is derived. Iniopterygians are also noted to possess proportionally large skulls and eyes, armor plates composed of dentin, and "tooth-whorls" of fused teeth. Their elongated pectoral fins bore large, denticle-covered spines, and they are thought to have used them to swim using a "flying" motion. The iniopterygians were comparatively small chondrichthyans, with the largest species reaching only 50 cm (20 in) in length.
Ornithoprion is a genus of extinct cartilaginous fish in the family Caseodontidae. The only species, O. hertwigi, lived during the Moscovian stage of the Pennsylvanian, 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 skull anatomy of eugeneodonts; a group which includes O. hertwigi and which were previously known primarily from isolated teeth. The genus name, which is derived from the ancient Greek órnith- meaning 'bird' and príōn meaning 'saw', was inspired by the animal's vaguely bird-like skull and the saw-like appearance of the lower teeth. The species name honors Oscar Hertwig.
Dracopristis is an extinct genus of ctenacanth that lived during the Carboniferous period in North America, around 307 million years ago. The species was discovered in the Kinney Brick Quarry in New Mexico, USA. Like many fossils from the site, the fossils of Dracopristis are very well-preserved. A single species is known, Dracopristis hoffmanorum, which is named in honor of Ralph and Jeanette Hoffman, the owners of the quarry. Prior to being scientific named, D. hoffmanorum was informally referred to as the "Godzilla shark".
Romerodus is an extinct genus of cartilaginous fish in the family Caseodontidae. While it and the rest of its family were historically considered elasmobranchs related to sharks and rays, they are now regarded as holocephalans, a diverse subclass which is today only represented by chimaeras. Romerodus is known from the Carboniferous and possibly Permian periods of North America, and the only named species, R. orodontus, was discovered in organic shale deposits in the U.S. state of Nebraska. It is one of few members of its order, the Eugeneodontida, that is known from multiple complete, well preserved body fossils, and is thus an important taxon for understanding the anatomy and ecology of less well preserved eugeneodonts such as Helicoprion. The genus name honors paleontologist Alfred Romer.
Myriacanthidae is an extinct family of holocephalan cartilaginous fish, closely related to living chimaeras. Fossils are known from the latest Triassic (Rhaetian) and Early Jurassic of Europe.
Chimaeropsis is an extinct genus of cartilaginous fish related to modern chimaeras, known from the Jurassic of Europe.
