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Euchondrocephali
Holocephali (Sometimes spelled Holocephala; Greek for "complete head" in reference to the fusion of upper jaw with the rest of the skull) is a subclass of cartilaginous fish. While the only living holocephalans are three families within a single order which together are commonly known as chimaeras, the group includes many extinct orders and was far more diverse during the Paleozoic and Mesozoic 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, elasmobranchs such as sharks and rays, during the Early Devonian or Silurian period. Extinct holocephalans are typically divided into a number of orders, although the interrelationships of these groups are poorly understood. Several different definitions of Holocephali exist, with the group sometimes considered a less inclusiv ... [...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] |
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] |
Romanization Of Greek
Romanization of Greek is the transliteration ( letter-mapping) or transcription (sound-mapping) of text from the Greek alphabet into the Latin alphabet. History The conventions for writing and romanizing Ancient Greek and Modern Greek differ markedly. The sound of the English letter B () was written as in ancient Greek but is now written as the digraph , while the modern sounds like the English letter V () instead. The Greek name became Johannes in Latin and then John in English, but in modern Greek has become ; this might be written as Yannis, Jani, Ioannis, Yiannis, or Giannis, but not Giannes or Giannēs as it would be for ancient Greek. The word might variously appear as Hagiοs, Agios, Aghios, or Ayios, or simply be translated as " Holy" or "Saint" in English forms of Greek placenames. Traditional English renderings of Greek names originated from Roman systems established in antiquity. The Roman alphabet itself was a form of the Cumaean alphabet derived f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shark
Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the Division (taxonomy), division Selachii and are the sister group to the Batoidea, Batomorphi (Batoidea, rays and skate (fish), skates). Some sources extend the term "shark" as an informal category including Extinction, extinct members of Chondrichthyes (cartilaginous fish) with a shark-like morphology, such as hybodonts. Shark-like chondrichthyans such as ''Cladoselache'' and ''Doliodus'' first appeared in the Devonian Period (419–359 million years), though some fossilized chondrichthyan-like scales are as old as the Ordovician, Late Ordovician (458–444 million years ago). The earliest confirmed modern sharks (Selachii) are known from the Early Jurassic around , with the oldest known member being ''Agaleus'', though records of true shar ... [...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] |
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of '' Tiktaalik'' in the arctic of Canada. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. Early edition, published online before prin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Era (geology)
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardised international units of geological time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesozoic
The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian reptiles such as the dinosaurs, and of Gymnosperm, gymnosperms such as cycads, ginkgoaceae and Araucariaceae, araucarian conifers; a hot Greenhouse and icehouse earth, greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since Cambrian explosion, complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic. The era began in the wake of the Permian–Triassic extinction event, the largest mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs, Pterosaur, pterosaurs, Mosasaur, mosasaurs, and Plesiosaur, plesiosaurs. The Mesozoic was a time of significant tectonic, climatic, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleozoic
The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of the Mesozoic Era. The Paleozoic is subdivided into six period (geology), geologic periods (from oldest to youngest), Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Some geological timescales divide the Paleozoic informally into early and late sub-eras: the Early Paleozoic consisting of the Cambrian, Ordovician and Silurian; the Late Paleozoic consisting of the Devonian, Carboniferous and Permian. The name ''Paleozoic'' was first used by Adam Sedgwick (1785–1873) in 1838 to describe the Cambrian and Ordovician periods. It was redefined by John Phillips (geologist), John Phillips (1800–1874) in 1840 to cover the Cambrian to Permian periods. It is derived from the Ancient Greek, Greek ''palaiós'' (π� ... [...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] |
Order (biology)
Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. An immediately higher rank, superorder, is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families. What does and does not belong to each order is determined by a taxonomist, as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with a capital letter. For some groups of organisms, their orders may follow consist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
