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Urumaco Formation
The Urumaco Formation is a formation in Venezuela that includes deposits from the Late Miocene. It is the site of several "giant forms": the turtles, crocodiles, sloths and rodents of Urumaco are among the largest of their groups. Location The Urumaco formation is located in the Urumaco region in the Caribbean coastal Falcón state. The deposits date from 10 to 5.3 million years ago and the Urumaco formation was deposited in an area with large rivers, swamps, estuaries, lagoons and shallow coastal seas. These conditions in the Late Miocene contrast strongly with the current dry environment in the area today. Fauna Cartilaginous fish There are 21 known species of cartilaginous fishes from the Urumaco Formation, belonging to the orders Lamniformes, Carcharhiniformes, Myliobatiformes and Rajiformes. ''Carcharhinus caquetius'' is an endemic species of predator shark from Urumaco. A large number of well-preserved fossils of the sawfish ''Pristis rostra'' have been found in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lamniformes
The Lamniformes (, from Greek ''lamna'' "fish of prey") are an order (biology), order of sharks commonly known as mackerel sharks (which may also refer specifically to the family Lamnidae). It includes some of the most familiar species of sharks, such as the great white shark, great white, as well as more unusual representatives, such as the goblin shark and megamouth shark. Members of the order are distinguished by possessing two dorsal fins, an anal fin, five gill, gill slits, eyes without nictitating membranes, and a mouth extending behind the eyes. Species in two families of Lamniformes – Lamnidae and Alopiidae – are distinguished for maintaining a higher body temperature than the surrounding water. Members of the group include Macro-predator, macropredators, generally of medium-large size, including the largest macropredatory shark ever, the extinct ''Otodus megalodon,'' as well as large planktivores. The oldest member of the group is the small (~ long) carpet shark-lik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiger Shark
The tiger shark (''Galeocerdo cuvier'') is a species of requiem shark and the last extant member of the family Galeocerdonidae. It is a large macropredator, capable of attaining a length over . Populations are found in many tropical and temperate waters, especially around central Pacific islands. Its name derives from the dark stripes down its body, which resemble a tiger's pattern, but fade as the shark matures. The tiger shark is a solitary, mostly nocturnal hunter. It is notable for having the widest food spectrum of all sharks, with a range of prey that includes crustaceans, fish, seals, birds, squid, turtles, sea snakes, dolphins, and even other smaller sharks. It also has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Though apex predators, tiger sharks are sometimes taken as prey by groups of killer whales. It is considered a near threatened species because of finning and fishing by humans. The tiger s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smooth Hammerhead Shark
The smooth hammerhead (''Sphyrna zygaena'') is a species of hammerhead shark, and part of the family Sphyrnidae. This species is named "smooth hammerhead" because of the distinctive shape of the head, which is flattened and laterally extended into a hammer shape (called the "cephalofoil"), without an indentation in the middle of the front margin (hence "smooth"). Unlike other hammerheads, this species prefers temperate waters and occurs worldwide at medium latitudes. In the summer, these sharks migrate towards the poles following cool water masses, sometimes forming schools numbering in the hundreds to thousands. The second-largest hammerhead shark after the great hammerhead shark, the smooth hammerhead can measure up to long. It is an active predator that takes a wide variety of bony fishes and invertebrates, with larger individuals also feeding on sharks and rays. As in the rest of its family, this shark is viviparous and gives birth to litters of 20–40 pups. A relative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spotted Eagle Ray
The spotted eagle ray (''Aetobatus narinari'') is a cartilaginous fish of the eagle ray family, Myliobatidae. As traditionally recognized, it is found globally in tropical regions, including the Atlantic, Pacific and Indian Oceans. Recent authorities have restricted it to the Atlantic (including the Caribbean and Gulf of Mexico) with other populations recognized as the ocellated eagle ray (''A. ocellatus'') and Pacific white-spotted eagle ray (''A. laticeps''). Spotted eagle rays are most commonly seen alone, but occasionally swim in groups. They are ovoviviparous, the female retaining the eggs then releasing the young as miniature versions of the parent. This ray can be identified by its dark dorsal surface covered in white spots or rings. Near the base of the ray's relatively long tail, just behind the pelvic fins, are several venomous, barbed stingers. Spotted eagle rays commonly feed on small fish and crustaceans, and will sometimes dig with their snouts to look for foo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megalodon
Megalodon (''Otodus megalodon''), meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark (''Carcharodon carcharias''). However, it is now classified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous. While regarded as one of the largest and most powerful predators to have ever lived, the megalodon is only known from fragmentary remains, and its appearance and maximum size are uncertain. Scientists differ on whether it would have more closely resembled a stockier version of the great white shark, the whale shark (''Rhincodon typus''), the basking shark (''Cetorhinus maximus'') or the sand tiger shark (''Carcharias taurus''). The most recent estimate with the least error range suggests a maximum length e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pristis Rostra
''Pristis'' is a genus of sawfish of the family Pristidae. These large fish are found worldwide in tropical and subtropical regions in coastal marine waters, estuaries, and freshwater lakes and rivers. Sawfish have declined drastically and all species are considered critically endangered today. Taxonomy The scientific genus name ''Pristis'' is derived from the Greek word for saw. Living species Recent authorities recognize four species: * ''Pristis clavata'' Garman, 1906 — dwarf sawfish, Queensland sawfish * ''Pristis pectinata'' Latham, 1794 — smalltooth sawfish * ''Pristis pristis'' (Linnaeus, 1758) — largetooth sawfish, common sawfish, freshwater sawfish, Leichhardt's sawfish * ''Pristis zijsron'' Bleeker, 1851 — longcomb sawfish, green sawfish These are divided into two species groups. Most are considered a part of the smalltooth group, except ''P. pristis'' which is the sole member of the largetooth group.Faria, V. V.; McDavitt, M. T.; Charvet, P.; Wiley, T. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pristis
''Pristis'' is a genus of sawfish of the family Pristidae. These large fish are found worldwide in tropical and subtropical regions in coastal marine waters, estuaries, and freshwater lakes and rivers. Sawfish have declined drastically and all species are considered critically endangered today. Taxonomy The scientific genus name ''Pristis'' is derived from the Greek word for saw. Living species Recent authorities recognize four species: * '' Pristis clavata'' Garman, 1906 — dwarf sawfish, Queensland sawfish * '' Pristis pectinata'' Latham, 1794 — smalltooth sawfish * '' Pristis pristis'' (Linnaeus, 1758) — largetooth sawfish, common sawfish, freshwater sawfish, Leichhardt's sawfish * '' Pristis zijsron'' Bleeker, 1851 — longcomb sawfish, green sawfish These are divided into two species groups. Most are considered a part of the smalltooth group, except ''P. pristis'' which is the sole member of the largetooth group.Faria, V. V.; McDavitt, M. T.; Charvet, P.; Wiley ... [...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''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endemic (biogeography)
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can be also be referred to as an ''endemism'' or in scientific literature as an ''endemite''. For example '' Cytisus aeolicus'' is an endemite of the Italian flora. '' Adzharia renschi'' was once believed to be an endemite of the Caucasus, but it was later discovered to be a non-indigenous species from South America belonging to a different genus. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. A rare alternative term for a species that is endemic is "precinctive", which applies to s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcharhinus Caquetius
''Carcharhinus'' is the type genus of the family Carcharhinidae, the requiem sharks. One of 12 genera in its family, it contains over half of the species therein. It contains 35 extant and eight extinct species to date, with likely more species yet to be described. Species Extant T Type species Fossil See also * List of prehistoric cartilaginous fish genera This list of prehistoric cartilaginous fish genera is an attempt to create a comprehensive listing of all genera that have ever been included in the class chondrichthyes ''and'' are known from the fossil record. This list excludes purely vernacul ... References Bibliography * * * * * * * {{Taxonbar, from=Q312359 Shark genera Extant Eocene first appearances Taxa named by Henri Marie Ducrotay de Blainville ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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