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Aetiocetus
''Aetiocetus'' is a genus of extinct basal mysticete, or baleen whale that lived , in the Oligocene in the North Pacific ocean, around Japan, Mexico, and Oregon, U.S. It was first described by Douglas Emlong in 1966 and currently contains known four species, ''A. cotylalveus'', ''A. polydentatus'', ''A. tomitai'', and ''A. weltoni''. These whales are remarkable for their retention of teeth and presence of nutrient foramina, indicating that they possessed baleen. Thus, Aetiocetus represents the transition from teeth to baleen in Oligocene mysticetes. Baleen is a highly derived character, or synapomorphy, of mysticetes, and is a keratinous structure that grows from the palate, or roof of the mouth, of the whale. The presence of baleen is inferred from the fossil record in the skull of ''Aetiocetus''. ''Aetiocetus'' is known from both sides of the Pacific Ocean: it was first documented in Oregon, United States, but it is also known from Japan and Mexico. The genus is currently ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aetiocetus BW
''Aetiocetus'' is a genus of extinct basal mysticete, or baleen whale that lived , in the Oligocene in the North Pacific ocean, around Japan, Mexico, and Oregon, U.S. It was first described by Douglas Emlong in 1966 and currently contains known four species, ''A. cotylalveus'', ''A. polydentatus'', ''A. tomitai'', and ''A. weltoni''. These whales are remarkable for their retention of teeth and presence of nutrient foramina, indicating that they possessed baleen. Thus, Aetiocetus represents the transition from teeth to baleen in Oligocene mysticetes. Baleen is a highly derived character, or synapomorphy, of mysticetes, and is a keratinous structure that grows from the palate, or roof of the mouth, of the whale. The presence of baleen is inferred from the fossil record in the skull of ''Aetiocetus''. ''Aetiocetus'' is known from both sides of the Pacific Ocean: it was first documented in Oregon, United States, but it is also known from Japan and Mexico. The genus is currently c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mysticeti
Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their mouths to sieve planktonic creatures from the water. Mysticeti comprises the families Balaenidae (right and bowhead whales), Balaenopteridae (rorquals and the gray whale), and Cetotheriidae (the pygmy right whale). There are currently 16 species of baleen whales. While cetaceans were historically thought to have descended from mesonychids, molecular evidence instead supports them as a clade of even-toed ungulates (Artiodactyla). Baleen whales split from toothed whales (Odontoceti) around 34 million years ago. Baleen whales range in size from the and pygmy right whale to the and blue whale, the largest known animal to have ever existed. They are sexually dimorphic. Baleen whales can have streamlined or large bodies, depending on th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baleen Whale
Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their mouths to sieve planktonic creatures from the water. Mysticeti comprises the families Balaenidae (right and bowhead whales), Balaenopteridae (rorquals and the gray whale), and Cetotheriidae (the pygmy right whale). There are currently 16 species of baleen whales. While cetaceans were historically thought to have descended from mesonychids, molecular evidence instead supports them as a clade of even-toed ungulates (Artiodactyla). Baleen whales split from toothed whales (Odontoceti) around 34 million years ago. Baleen whales range in size from the and pygmy right whale to the and blue whale, the largest known animal to have ever existed. They are sexually dimorphic. Baleen whales can have streamlined or large bodies, depending on th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yaquina Formation
The Yaquina Formation is a geologic formation in Oregon. It preserves fossils dating back to the Paleogene period. Fossil content Mammals Carnivorans Cetaceans Desmostylians Fish Bony fish Sharks See also * List of fossiliferous stratigraphic units in Oregon * Paleontology in Oregon The location of the state of Oregon Paleontology in Oregon refers to paleontological research occurring within or conducted by people from the U.S. state of Oregon. Oregon's geologic record extends back approximately 400 million years ago to the ... References Sources * Paleogene geology of Oregon Formations {{Paleogene-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morawan Formation
The Morawan Formation is a Chattian age siliceous marine geological formation of the Oligo-Miocene Japanese Kawakami Group of eastern Hokkaido prefecture. The formation is fossil rich and contains source units where toothed baleen whales (Aetiocetidae) and Desmostylians have been discovered. The Morawan Formation is a very siliceous unit containing hard platy shales interbedded with tuffaceous mudstones and sandstones, and some pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular v .... The unnamed lower member is a hard platy shale alternating with beds of tuffaceous mudstones and sandstones, the Kamirawan member is a tuffaceous sandstone with pumice, the Lower Hard Shale is a very siliceous hard shale with tuffaceous sandstones and mudstones, and the Middle Hard Shales and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chonecetus
''Chonecetus'' is an extinct genus of primitive baleen whale of the family Aetiocetidae that lived in the Oligocene period. Its fossils have been found in Canada, in the northeast Pacific. It was first named by L.S. Russell in 1968, and contains one species, ''C. sookensis''. Like ''Aetiocetus'', ''Chonecetus'' possessed both multicusped teeth and the nutrient foramina required for baleen.''Marine Mammals: Evolutionary Biology''; page 62. By Annalisa Berta, James L. Sumich, and Kit M. Kovacs, published 2005; Academic Press. Retrieved on July 1, 2008. ''Chonecetus'' closely resembled a modern Mysticeti, with an elongate, streamlined body supporting a pair of paddle-shaped forelimbs, and a horizontal tail fluke strengthened by fibrous cartilage. Sister Taxa *''Aetiocetus'' *''Ashorocetus'' *''Fucaia'' *''Morawanocetus ''Morawanocetus'' is a genus of extinct primitive baleen whale from the family Aetiocetidae that existed during the Chattian stage of the Oligocene epoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Douglas Emlong
Douglas Ralph Emlong (April 17, 1942–June 1980) was an amateur fossil collector from the Oregon Coast in the northwestern United States. His collections contributed to the discovery and description of numerous extinct marine mammal species, many of which are ancestral to extant groups. Described as an 'indefatigable' fossil collector with 'Promethian prowess in discovery of unprecedented vertebrate fossils', he contributed substantially to the field from the age of fourteen. The ancestral pinniped '' Enaliarctos emlongi'' was named in his honor by Annalisa Berta in 1991. Discoveries Fossils discovered by Douglas Emlong include: Marine Mammals: *''Aetiocetus cotylalveus'', an early, toothed relative of baleen whales and evolutionary link between ancient and modern cetaceans *'' Simocetus'', a genus of bottom-feeding pug-nosed whales which may have had comparable echolocation abilities to modern toothed whales *''Behemotops'', a genus of primitive, elephant-like desmostylians ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen(s). Article 67.1 A similar concept is used for suprageneric groups and called a type genus. In botanical nomenclature, these terms have no formal standing under the code of nomenclature, but are sometimes borrowed from zoological nomenclature. In botany, the type of a genus name is a specimen (or, rarely, an illustration) which is also the type of a species name. The species name that has that type can also be referred to as the type of the genus name. Names of genus and family ranks, the various subdivisions of those ranks, and some higher-rank names based on genus names, have such types. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiomorphic
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and synapomorphy, all mean a trait shared between species because they share an ancestral species. Apomorphic and synapomorphic characteristics convey much information about evolutionary clades and can be used to define taxa. However, plesiomorphic and symplesiomorphic characteristics cannot. The term ''symplesiomorphy'' was introduced in 1950 by German entomologist Willi Hennig. Examples A backbone is a plesiomorphic trait shared by birds and mammals, and does not help in placing an animal in one or the other of these two clades. Birds and mammals share this trait because both clades are descended from the same far distant ancestor. Other clades, e.g. snakes, lizards, turtles, fish, frogs, all have backbones and none are either birds no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphic Section
A stratigraphic section is a sequence of layers of rocks in the order they were deposited. It is based on the principle of original horizontality, which states that layers of sediment are originally deposited horizontally under the action of gravity. Biostratigraphers estimate the age of stratigraphic sections by using the faunal assemblages contained within rock samples from outcrop and drill cores.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Biology'', 8th ed., Oxford University Press, 2019. Geochronologists precisely date rocks within the stratigraphic section to provide better absolute bounds on the timing and rates of deposition. Magnetic stratigraphers look for signs of magnetic reversals in igneous rock units within the drill cores. Other scientists perform stable-isotope studies on the rocks to gain information about past climate. Stratigraphic sections can also be used to locate areas for water, coal, and hydrocarbon extraction, particular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, pp.381-382 Although its permeability and porosity is relatively low, siltstone is sometimes a tight gas reservoir rock, an unconventional reservoir for natural gas that requires hydraulic fracturing for economic gas production. Siltstone was prized in ancient Egypt for manufacturing statuary and cosmetic palettes. The siltstone quarried at Wadi Hammamat was a hard, fine-grained siltstone that resisted flaking and was almost ideal for such uses. Description There is not complete agreement on the definition of siltstone. One definition is that siltstone is mudrock ( clastic sedimentary rock containing at least 50% clay and silt) in which at least 2/3 of the clay and silt fraction is composed of silt-sized particles. Silt is defined a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic groups are typically characterised by shared derived characteristics ( synapomorphies), which distinguish organisms in the clade from other organisms. An equivalent term is holophyly. The word "mono-phyly" means "one-tribe" in Greek. Monophyly is contrasted with paraphyly and polyphyly as shown in the second diagram. A ''paraphyletic group'' consists of all of the descendants of a common ancestor minus one or more monophyletic groups. A '' polyphyletic group'' is characterized by convergent features or habits of scientific interest (for example, night-active primates, fruit trees, aquatic insects). The features by which a polyphyletic group is differentiated from others are not inherited from a common ancestor. These definitions have tak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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