|
Holocephali
Holocephali (Sometimes spelled Holocephala; Romanization of Greek, Greek for "complete head" in reference to the fusion of Palatoquadrate, upper jaw with the rest of the skull) is a Subclass (biology), subclass of Chondrichthyes, cartilaginous fish. While the only living holocephalans are three families within a single Order (biology), order which together are commonly known as chimaeras, the group includes many extinct orders and was far more diverse during the Paleozoic and Mesozoic Era (geology), eras. The earliest known fossils of holocephalans date to the Middle Devonian period, and the group likely reached its peak diversity during the following Carboniferous period. Molecular clock studies suggest that the subclass diverged from its closest relatives, Elasmobranchii, elasmobranchs such as sharks and Batomorphi, rays, during the Early Devonian or Silurian period. Extinct holocephalans are typically divided into a number of orders, although the interrelationships of these gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyes
Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates and sawfish) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Extant chondrichthyans range in size from the finless sleeper ray to the over whale shark. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chimaera
Chimaeras are Chondrichthyes, cartilaginous fish in the order (biology), order Chimaeriformes (), known informally as ghost sharks, rat fish (not to be confused with rattails), spookfish, or rabbit fish; the last two names are also applied to Barreleye, Opisthoproctidae and Rabbitfish, Siganidae, respectively. At one time a "diverse and abundant" group (based on the fossil record), their closest living relatives are sharks and ray (fish), rays, though their last common ancestor with them lived nearly 400 million years ago. Living species (aside from plough-nose chimaeras) are largely confined to deep water. Anatomy Chimaeras are soft-bodied, shark-like fish with bulky heads and long, tapered tails; measured from the tail, they can grow up to in length. Like other members of the class Chondrichthyes, chimaera skeletons are entirely cartilaginous, or composed of cartilage. Males use forehead denticles to grasp a female by a fin during copulation. The Branchial arch, gill arche ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debeeriidae
Debeeriidae is a family of holocephalan fishes from the Mississippian subperiod of the Carboniferous. It is the only family of the order Debeeriiformes. It is named after the type genus, ''Debeerius'', which itself is named in honor of Gavin de Beer. Members of this family and order possess a spine on the first dorsal fin, an opercular cover over the gills, and an autodiastylic (two-jointed) jaw suspension. Both genera in the family are known from exceptionally well-preserved specimens found in the Bear Gulch Limestone member of the Heath Formation The Big Snowy Group is a stratigraphical unit of Chesterian age in the Williston Basin. It takes the name from Big Snowy Mountains in Montana, and was first described on the north slopes of the mountain by H.W. Smith in 1935. Lithology Subdiv .... References Holocephali Fossil taxa described in 2000 Mississippian fish of North America Prehistoric cartilaginous fish families {{Paleo-cartilaginous-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasmobranchii
Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks ( division Selachii), and batomorphs (division Batomorphi, including rays, skates, and sawfish). Members of this subclass are characterised by having five to seven pairs of gill slits 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. The definition of the clade is unclear with respect to fossil chondrichthyans. Some authors consider it as equivalent to Neoselachii (the crown group clade including modern sharks, rays, and all o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous
The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the Permian Period, Ma. It is the fifth and penultimate period of the Paleozoic era and the fifth period of the Phanerozoic eon (geology), eon. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian (geology), Mississippian and the later Pennsylvanian (geology), Pennsylvanian. The name ''Carboniferous'' means "coal-bearing", from the Latin ("coal") and ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern "system" names, it was coined by geologists William Conybeare (geologist), William Conybeare and William Phillips (geologist), William Phillips in 1822, based on a study of the British rock succession. Carboniferous is the per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menaspiformes
Menaspiformes are an extinct order of holocephalans known from the Carboniferous and Permian periods, with a possible member, ''Listracanthus'', known from the Early Triassic. Members of the order are believed to be durophagous Durophagy is the eating behavior of animals that consume hard-shelled or exoskeleton-bearing organisms, such as corals, shelled mollusks, or crabs. It is mostly used to describe fish, but is also used when describing reptiles, including fossil t ... benthic carnivores. While historically menaspiforms were classified under Chimaeriformes, they are today recognized as a separate order. References Holocephali Prehistoric cartilaginous fish orders {{Paleo-holocephalan-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batomorphi
Batomorphi is a division of cartilaginous fishes, commonly known as rays, this taxon is also known as the superorder Batoidea, but the 5th edition of ''Fishes of the World'' classifies it as the division Batomorphi. They and their close relatives, the sharks, compose the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces. Anatomy Batomorphs are flat-bodied, and, like sharks, are cartilaginous fish, meaning they have a boneless skeleton made of a tough, elastic cartilage. Most batomorphs have five ventral slot-like body openings called gill slits that lead from the gills, but the Hexatrygonidae have six. Batomorph gill slits lie under the pectoral fins on the underside, whereas a shark's are on the sides of the head. Most batomorphs have a flat, mantle-l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orodontiformes
Orodontiformes is an extinct group of cartilaginous fish, known from the Late Devonian and Carboniferous periods. They are part of Euchondrocephali (Holocephali ''sensu lato''), making their closest living relatives chimaeras. Most members are only known from teeth, which are low and rounded, and designed for crushing prey (durophagy). The group in its totality has been described as "undoubtedly artificial" (i.e. non-monophyletic).Ginter, M., Hampe, O., and Duffin, C.J., 2010, Chondrichthyes. Paleozoic Elasmobranchii: teeth, in Schultze, H.-P., ed., Handbook of Paleoichthyology, v. 3D: München, Friedrich Pfeil, pp. 109-117 Several species of '' Orodus'' are known from specimens preserving the body as well as the teeth. Description According to Ginter et al 2010, the teeth of Orodontiformes are distinguished by the following features: The only known members of the Orodontiformes known from skeletal material are two species of '' Orodus'', ''Orodus greggi'' ''and Orodus micropte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debeerius
''Debeerius'' is a genus of chondrichthyan from the Mississippian age Bear Gulch Limestone of Montana, United States. It is named after Gavin de Beer. One species, ''D. ellefseni'', is known, which is preserved in very fine detail. Melanin preserved in fossils of ''D. ellefseni'' indicates it possessed dark stripes down the length of its body. The jaw suspension of ''Debeerius'' was autodiastylic (two jointed), and it is considered a member of the subclass Holocephali Holocephali (Sometimes spelled Holocephala; Romanization of Greek, Greek for "complete head" in reference to the fusion of Palatoquadrate, upper jaw with the rest of the skull) is a Subclass (biology), subclass of Chondrichthyes, cartilaginous fi .... References Holocephali Monotypic prehistoric cartilaginous fish genera Fossil taxa described in 2000 Mississippian fish of North America {{Paleo-cartilaginous-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinochimaera
''Echinochimaera'' ("prickly chimaera") 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. Taxonomy The genus' name derives from the Greek ''εχινό'' (''echino'') meaning spiny, and chimaera. It is assigned to the order Chimaeriformes. Species The two known ''Echinochimaera'' species lived in the Upper Mississippian (Serpukhovian). Fossils of the species were found in the Bear Gulch Limestone in Montana, United States. Both species have rounded bodies and paddle-like tails as well as large pectoral fins, two dorsal fins and a jaw fused to the braincase. The paddle-like tails indicate that ''E. meltoni'' was likely not a predator nor a fast swimmer. ''Echinochimaera meltoni'' ''E. meltoni'' was first described by Richard Lund, an Adelphi University palaeontologist, in 1977. The fossils found of ''E. meltoni'' have shown a great deal of sexual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chimaera Opalescens
The opal chimaera (''Chimaera opalescens'') is a chimaera species in the family Chimaeridae The Chimaeridae, or short-nosed chimaeras, are a family (biology), family of cartilaginous fish. They resemble other Chimaeriformes, chimaeras in general form and habits, but have short, rounded snouts, without the modifications found in relate ..., which lives in the northeastern Atlantic Ocean. References Chimaera Fish of the Atlantic Ocean {{holocephalan-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
