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Squalodontidae
Squalodontidae or the shark-toothed dolphins is an extinct family of large toothed whales who had long narrow jaws. Squalodontids are known from all continents except Antarctica, from the Oligocene to the Neogene, but they had a maximal diversity and global distribution during the Late Oligocene and Early to Middle Miocene (). With their cosmopolitan Miocene distribution and heterodont dentition, squalodontids are the most common and basal platanistoids. They are relatively large odontocetes, comparable in size to extant mesoplodont whales. The premaxillae on their elongated rostrum have large and slightly convex fossae for the air sacs associated with the presence of a melon, indicating the ability for echolocation. ''Squalodon'' and ''Eosqualodon'' are based on partial or complete skulls. The synapomorphic traits of the family are, however, based mostly on one of the bones of the inner ear, the periotic bone, which is unknown in these genera except in ''Squalodon''. The mon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squalodon
''Squalodon'' is an extinct genus of whales of the Oligocene and Miocene epochs, belonging to the family Squalodontidae. Named by Jean-Pierre Sylvestre de Grateloup in 1840, it was originally believed to be an iguanodontid dinosaur but has since been reclassified. The name ''Squalodon'' comes from ''Squalus'', a genus of shark. As a result, its name means "shark tooth". Its closest modern relatives are the 2 species of the genus South Asian river dolphin, Platanista ( the Ganges river dolphin and Indus river dolphin). Description Species of ''Squalodon'' are odontocetes that lived during the late Oligocene into the middle Miocene, about 28 to 15 million years ago. The genus ''Squalodon'' belongs to the order Odontoceti, the toothed whales. Their name is derived from the term ''Wiktionary:squalus#Noun, Squalus'' because their cheek teeth were thought to resemble the teeth of a Spurdog, ''Squalus'' shark. The largest species, ''Squalodon whitmorei'', reached up to 5.5 meters in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squalodontidae
Squalodontidae or the shark-toothed dolphins is an extinct family of large toothed whales who had long narrow jaws. Squalodontids are known from all continents except Antarctica, from the Oligocene to the Neogene, but they had a maximal diversity and global distribution during the Late Oligocene and Early to Middle Miocene (). With their cosmopolitan Miocene distribution and heterodont dentition, squalodontids are the most common and basal platanistoids. They are relatively large odontocetes, comparable in size to extant mesoplodont whales. The premaxillae on their elongated rostrum have large and slightly convex fossae for the air sacs associated with the presence of a melon, indicating the ability for echolocation. ''Squalodon'' and ''Eosqualodon'' are based on partial or complete skulls. The synapomorphic traits of the family are, however, based mostly on one of the bones of the inner ear, the periotic bone, which is unknown in these genera except in ''Squalodon''. The mon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toothed Whales
The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales with teeth, such as beaked whales and the sperm whales. 73 species of toothed whales are described. They are one of two living groups of cetaceans, the other being the baleen whales (Mysticeti), which have baleen instead of teeth. The two groups are thought to have diverged around 34 million years ago (mya). Toothed whales range in size from the and vaquita to the and sperm whale. Several species of odontocetes exhibit sexual dimorphism, in that there are size or other morphological differences between females and males. They have streamlined bodies and two limbs that are modified into flippers. Some can travel at up to 30 knots. Odontocetes have conical teeth designed for catching fish or squid. They have well-developed hearing that is well adapted for both air and water, so much so that some can survive even if they ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periotic Bone
The periotic bone is the single bone that surrounds the inner ear of birds and mammals. It is formed from the fusion of the prootic, epiotic, and opisthotic bones, and in Cetacea forms a complex with the tympanic bone The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal. It originates as a separate bone (tympanic .... References Skeletal system Mammal anatomy {{Vertebrate anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chattian First Appearances
The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage of the Miocene). Stratigraphic definition The Chattian was introduced by Austrian palaeontologist Theodor Fuchs Theodor Fuchs (15 September 1842 in Eperies – 5 October 1925 in Steinach am Brenner) was an Austrian geologist and paleontologist. He studied geology and paleontology at the University of Vienna as a pupil of Eduard Suess (doctorate 1863). ... in 1894. Fuchs named the stage after the Chatti, a Germanic peoples, Germanic tribe.Berry, Edward W"The Mayence Basin, a Chapter of Geologic History" ''The Scientific Monthly'', Vol. 16, No. 2, February 1923. pp. 114. Retrieved March 18, 2020. The original type locality (geology), type locality was near the Germany, German city of Kassel. The base of the Chattian is at the extinct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Toothed Whales
Prehistory, also called pre-literary history, is the period of human history between the first known use of stone tools by hominins million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared years ago. It took thousands of years for writing systems to be widely adopted, with writing having spread to almost all cultures by the 19th century. The end of prehistory therefore came at different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. It is based on an old conception of history that without written records there could be no history. The most common conception today is that history is based on evidence, however the concept of prehistory hasn't been completely discarded. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeoceti
Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is an obsolete paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene (). Representing the earliest cetacean radiation, they include the initial amphibious stages in cetacean evolution, thus are the ancestors of both modern cetacean suborders, Mysticeti and Odontoceti. This initial diversification occurred in the shallow waters that separated India and Asia , resulting in some 30 species adapted to a fully oceanic life. Echolocation and filter-feeding evolved during a second radiation . All archaeocetes from the Ypresian (56–47.8 mya) and most from the Lutetian (47.8–41.3 mya) are known exclusively from Indo-Pakistan, but Bartonian (41.3–38.0 mya) and Priabonian (38.0–33.9 mya) genera are known from across Earth, including North America, Egypt, New Zealand, and Europe. Although no consensus exists regarding the mode of locomotion of which cetaceans were capabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atavism
In biology, an atavism is a modification of a biological traits structure or behavior whereby an ancestral genetic trait reappears after having been lost through evolutionary change in previous generations. Atavisms can occur in several ways, one of which is when genes for previously existing phenotypic features are preserved in DNA, and these become expressed through a mutation that either knocks out the dominant genes for the new traits or makes the old traits dominate the new one. A number of traits can vary as a result of shortening of the fetal development of a trait (neoteny) or by prolongation of the same. In such a case, a shift in the time a trait is allowed to develop before it is fixed can bring forth an ancestral phenotype. Atavisms are often seen as evidence of evolution. In social sciences, atavism is the tendency of reversion: for example, people in the modern era reverting to the ways of thinking and acting of a former time. The word ''atavism'' is derived fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean-Pierre Sylvestre De Grateloup
Jean-Pierre Sylvestre de Grateloup (31 December 1782 – 25 August 1862) was a French physician and naturalist. He completed his medical studies at Montpellier and remained attached to the countryside of the southwest of France. In company with his childhood friend Jean-Marie Léon Dufour (1780–1865) and Dufour's friend Jean-Baptiste Bory de Saint-Vincent (1778–1846) he expressed his enthusiasm for botany specializing in the study of cryptogams, the ferns and other plants that reproduce through spores. Then the shells found in the region attracted his attention, in particular those from the Adour.Grateloup, "Tableau des coquilles Fossiles qu'on rencontre dans des terrains calcaires tertiaires (faluns) des environs de Dax" in ''Actes de la Société linnéenne de Bordeaux'', 183;: ''Mémoire de géo-zoologie sur les oursins fossiles (échinides) qui se rencontrent dans les terrains caleaires des environs de Dax'', 1836; Conchyliologie fossile des terrains tertiaires du bassin de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Asian River Dolphin
South Asian river dolphins are toothed whales in the genus ''Platanista'', which inhabit the waterways of the Indian subcontinent. They were historically considered to be one species (''P. gangetica'') with the Ganges river dolphin and the Indus river dolphin being subspecies (''P. g. gangetica'' and ''P. g. minor'' respectively). Genetic and morphological evidence led to their being described as separate species in 2021. The Ganges and Indus river dolphins are estimated to have Split (phylogenetics), diverged 550,000 years ago. They are the only living members of the family Platanistidae and the superfamily Platanistoidea. Fossils of ancient relatives date to the late Oligocene. South Asian river dolphins are small but stocky cetaceans with long snouts or Rostrum (anatomy), rostra, broad flippers, and small dorsal fins. They have several unusual features. Living in murky river waters, they have eyes that are tiny and lensless; the dolphins rely instead on Animal echolocation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christian De Muizon
A Christian () is a person who follows or adheres to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. Christians form the largest religious community in the world. The words ''Christ'' and ''Christian'' derive from the Koine Greek title (), a translation of the Biblical Hebrew term ''mashiach'' () (usually rendered as ''messiah'' in English). While there are diverse interpretations of Christianity which sometimes conflict, they are united in believing that Jesus has a unique significance. The term ''Christian'' used as an adjective is descriptive of anything associated with Christianity or Christian churches, or in a proverbial sense "all that is noble, and good, and Christ-like." According to a 2011 Pew Research Center survey, there were 2.3 billion Christians around the world, up from about 600 million in 1910. Today, about 37% of all Christians live in the Americas, about 26% live in Europe, 24% live in sub-Saharan Africa, ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Dolphin
Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the Globicephalinae (round-headed whales, which include the false killer whale and pilot whale). Delphinidae is a family within the superfamily Delphinoidea, which also includes the porpoises (Phocoenidae) and the Monodontidae ( beluga whale and narwhal). River dolphins are relatives of the Delphinoidea. Oceanic dolphins range in size from the and Maui's dolphin to the and orca, the largest known dolphin. Several species exhibit sexual dimorphism; the males are larger than females. They have streamlined muscular bodies and two limbs that are modified into flippers. Though not quite as flexible as seals, some dolphins can travel at speeds 29 km/h (18 mph) for short distances. Most delphinids primarily eat fish, along wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
