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Harpagofututor
''Harpagofututor'' is an extinct genus of eel-like cartilaginous fish from the Early Carboniferous ( Mississippian). It is primarily known from complete specimens discovered in the Bear Gulch Limestone of Montana, as well as an isolated tooth from Whitrope, Scotland. Discovery and taxonomy ''Harpagofututor'' was first described in 1982, from several complete specimens discovered in the Bear Gulch Limestone of Montana by Adelphi University palaeontologist Richard Lund.Lund, Richard. "Harpagofututor volsellorhinus New Genus and Species (Chondrichthyes, Chondrenchelyiformes) from the Namurian Bear Gulch Limestone, Chondrenchelys problematica Traquair (Visean), and Their Sexual Dimorphism," ''Journal of Paleontology'', Vol. 56, No. 4, July 1982, pp. 938-958. There is only one named species, ''H. volsellorhinus'', which was described by Lund in 1982. A single specimen of indeterminate species is also known from a single tooth plate discovered in Whitrope, Scotland. The genus is pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Bear Gulch Limestone
The Bear Gulch Limestone is a limestone-rich Lens (geology), geological lens in central Montana, renowned for the quality of its marine fossils from the late Mississippian (geology), Mississippian subperiod, about 324 million years ago. It is exposed over a number of outcrops northeast of the Big Snowy Mountains, and is often considered a component of the more widespread Heath Formation. The Bear Gulch Limestone reconstructs a diverse, though isolated, marine ecosystem which developed near the end of the Serpukhovian age in the Carboniferous period. It is a lagerstätte, a particular type of rock unit with exceptional fossil preservation of both articulated skeletons and soft tissues. Bear Gulch fossils include a variety of fish, invertebrates, and algae occupying a number of different habitats within a preserved shallow bay. Fish include a high diversity of unusual Chondrichthyes, chondrichthyans (cartilaginous fish) and one of the oldest known lampreys, along with other vertebrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrenchelyidae
Chondrenchelyiformes is an extinct order of holocephalan cartilaginous fish, known from the Early Carboniferous of Europe and North America. There are currently two recognised genera known from largely complete remains, '' Chondrenchelys'' from the Visean of Scotland, and ''Harpagofututor'' from the Serpukhovian aged Bear Gulch Limestone of Montana, United States. Both genera have elongate, eel-like bodies, with their mouths having tooth plates similar to those of living chimaeras, to which they share numerous anatomical similarities indicating a close relationship. Isolated tooth plates assigned to the genus '' Platyxystrodus'' likely belong to members of the family, which would extend the range of the group into the late Carboniferous. Anatomy Chondrenchelyiformes generally have elongate bodies with tapered heads, the lower jaw (mandible) is elongate, and articulates with the quadrate bone of the skull below the posteior edge of the eye socket. The dentition is composed of to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clasper
In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's cloaca during mating. The act of mating in some fish including sharks usually includes one of the claspers raised to allow water into the siphon through a specific orifice. The clasper is then inserted into the cloaca, where it opens like an umbrella to anchor its position. The siphon then begins to contract, expelling water and sperm. The claspers of many shark species have spines or hooks, which may hold them in place during copulation. Many male holocephalans, including living chimaeras, have cephalic claspers (tenacula) on their heads, which are thought to aid in holding the female during mating. In entomology Entomology (from Ancient Greek ἔντομον (''éntomon''), meaning "insect", and -logy from λόγος (''lógos'') ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrinacodus
''Thrinacodus'' is an extinct genus of basal elasmobranch, found worldwide from the Late Devonian-Lower Carboniferous. The type species is ''Thrinacodus nanus''. Most species are only known from their tricuspid teeth. ''T. gracia'', originally placed in the separate genus ''Thrinacoselache'' from the Serpukhovian-aged Bear Gulch Limestone, of what is now Montana, is known from full body impressions, showing a long, slender eel-like body up to a metre in length, with an elongate rostrum. Stomach contents of ''T. gracia'' include remains of crustaceans and small chondrichthyan fish (''Harpagofututor'' and ''Falcatus ''Falcatus'' is an extinct genus of falcatid chondrichthyan which lived during the early Carboniferous Period in Bear Gulch bay in what is now Montana. Description This fish was quite small, only getting to around 25–30 cm or 10-12 i ...''). It is a member of the Phoebodontiformes. References Phoebodontiformes Carboniferous cartilaginous fish Fos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrenchelys
''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 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. See also * List of prehistoric cartilaginous fish This list of prehistoric cartilaginous fish genera is an attempt to create a comprehensive listing of all Genus, genera that have ever been included in the class chondrichthyes ''and'' are known from the fossi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous Cartilaginous Fish
The Carboniferous ( ) is a geologic period and system of the Paleozoic 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. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later 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 and William Phillips in 1822, based on a study of the British rock succession. Carboniferous is the period during which both terrestrial animal and land plant life was well established. Stegocephalia (four-limbed vertebrates including true tetrapods), whose forerunners (tetrapodomor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotypic Prehistoric Cartilaginous Fish Genera
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. Theoretical implications Monotypic taxa present several important theoretical challenges in biological classification. One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in a hierarchical system. ... [...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] |
Viviparity
In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juvenile that is at least metabolically independent. This is opposed to oviparity, where the embryos develop independently outside the mother in eggs until they are developed enough to break out as hatchlings; and ovoviviparity, where the embryos are developed in eggs that remain carried inside the mother's body until the hatchlings emerge from the mother as juveniles, similar to a live birth. Etymology The term "viviparity" and its adjective form "viviparous" both derive from the Latin ''vivus'', meaning "living"; and ''pario'', meaning "give birth to". Reproductive mode Five modes of reproduction have been differentiated in animals based on relations between zygote and parents. The five include two nonviviparous modes: ovulipari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
