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Keichousaurids
left, 220px, '' Pachypleurosaurus'' Pachypleurosauria is an extinct clade of primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from , with small heads, long necks, paddle-like limbs, and long, deep tails. The limb girdles are greatly reduced, so it is unlikely these animals could move about on land. The widely spaced peg-like teeth project at the front of the jaws, indicating that these animals fed on fish. In the species ''Prosantosaurus'', it was observed that they fed on small fishes and crustaceans which they devoured entirely and that its teeth regrew after they broke off. This was the first observation of tooth replacement in a European pachypleurosaur, the only other discovery of such an event was made in China. Classification Pachypleurosaurs were originally and are often still included within the Nothosauroidea (Carroll 1988, Benton 2004). In some more recen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Induan
The Induan is the first age of the Early Triassic epoch in the geologic timescale, or the lowest stage of the Lower Triassic series in chronostratigraphy. It spans the time between 251.902 Ma and Ma (million years ago). The Induan is sometimes divided into the Griesbachian and the Dienerian subages or substages. The Induan is preceded by the Changhsingian (latest Permian) and is followed by the Olenekian. The Induan is roughly coeval with the regional Feixianguanian Stage of China. Geology Stratigraphy The Triassic is the first period of the Mesozoic era. It is subdivided into the Lower, Middle, and Upper Triassic series, which are further subdivided into stages. The Induan is the first stage of the Lower Triassic, from 251.9 million to 251.2 million years ago, spanning the first 700,000 years after the Permian–Triassic extinction event. Stages can be defined globally or regionally. For global stratigraphic correlation, the International Commission on Stratigraphy (ICS) r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosantosaurus
''Prosantosaurus'' is a monotypic genus of pachypleurosaurian sauropterygian containing the single species ''Prosantosaurus scheffoldi'' discovered in Canton Grison of Switzerland. The genus is named after the Prosanto Formation near the Ducan mountains, where the skeletons were found, and the species for Beat Scheffold, a scientific illustrator from Zurich who contributed prominently to the research of the Triassic marine reptiles. Discovery Six skeletons of the species have been discovered within lime and marlstone sediments of the Upper Prosanto Formation in the Ducanfurgga southeast of Davos, Canton Grisons, at about 2700 m above sea level. They have been dated to the very early Ladinian of the Triassic period. Today, the Ducan mountains are located about northeast of Mount San Giorgio, a UNESCO world heritage site where other pachypleurosauria were found. In the past, the two locations have been up to apart from each other. The skeletons are accessible in the palae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nothosaur
Nothosaurs (order Nothosauroidea) were Triassic marine sauropterygian reptiles that may have lived like seals of today, catching food in water but coming ashore on rocks and beaches. They averaged about in length, with a long body and tail.F. v. Huene. 1956. Paläontologie und Phylogenie der Niederen Tetrapoden aleontology and Phylogeny of the Lower Tetrapods ''VEB Gustav Fischer Verlang, Jena'' 1-716 The feet were paddle-like, and are known to have been webbed in life, to help power the animal when swimming. The neck was quite long, and the head was elongated and flattened, and relatively small in relation to the body. The margins of the long jaws were equipped with numerous sharp outward-pointing teeth, indicating a diet of fish and squid. Taxonomy The Nothosauroidea consist of two suborders: * Pachypleurosauria, small primitive forms, and * Nothosauria (including two families Nothosauridae and Simosauridae), which evolved from pachypleurosaurs. The placement of pachypleuros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term ''cladus'' (plural ''cladi'') is often used in taxonomical literature. The common ancestor may be an individual, a population, or a species (extinct or extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between organisms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eosauropterygia
Sauropterygia (" lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became extinct at the end of that period. The plesiosaurs would continue to diversify until the end of the Mesozoic. Sauropterygians are united by a radical adaptation of their pectoral girdle, adapted to support powerful flipper strokes. Some later sauropterygians, such as the pliosaurs, developed a similar mechanism in their pelvis. Uniquely among reptiles, sauropterygians moved their tail vertically like modern cetaceans and sirenians. Origins and evolution The earliest sauropterygians appeared about 247 million years ago (Ma), at the start of the Middle Triassic: the first definite sauropterygian with exact stratigraphic datum lies within the Spathian division of the Olenekian era in South China. Early examples were small (around 60&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same taxonomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladistics
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived characteristics ( synapomorphies'')'' that are not present in more distant groups and ancestors. However, from an empirical perspective, common ancestors are inferences based on a cladistic hypothesis of relationships of taxa whose character states can be observed. Theoretically, a last common ancestor and all its descendants constitute a (minimal) clade. Importantly, all descendants stay in their overarching ancestral clade. For example, if the terms ''worms'' or ''fishes'' were used within a ''strict'' cladistic framework, these terms would include humans. Many of these terms are normally used paraphyletically, outside of cladistics, e.g. as a 'grade', which are fruitless to precisely delineate, especially when including extinct species. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swissinfo
SWI swissinfo.ch is a multilingual news and information platform produced by the Swiss Broadcasting Corporation (SRG SSR). Its content is Swiss-centred, with top priority given to in-depth information on politics, the economy, the arts, science, education, and direct democracy. Switzerland's international political, economic and cultural relations are other key points of focus. The website is available in ten languages. History In the mid-1990s, economic circumstances forced swissinfo.ch to take a new strategic direction. The internet was advancing fast, heralding a new era for the producing journalists and the Swiss Radio International (SRI) audience alike. The German, French, English and Portuguese sites went online in 1999. The Italian, Japanese and Spanish sites followed in 2000, with Arabic going live on 1 February 2001 and Chinese in September of the same year. Within just two years, the internet platform for expatriate Swiss was already better known than SRI's short-wav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limb Girdles
Limb may refer to: Science and technology *Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, the border or upper spreading part of a petal or sepal *Limb, in a measuring instrument, the graduated edge of a circle or arc Music * ''Limb'' (album), by Foetus, 2009 *''Limb'', an album by Justin Clayton, 1999 *"Limbs", a song by Emma Pollock from ''Watch the Fireworks'', 2007 *Limb Music, a German record label Other uses *Limb (surname), a list of people *Limb McKenry (1888–1956), American baseball pitcher *Limb Brook, a stream in Sheffield, South Yorkshire, England *Limbs Dance Company, in Auckland, New Zealand *Limbs, in archery, the upper and lower working parts of the bow; see recurve bow *Bresso Airfield, Bresso, Italy (ICAO code) *Limbu script (ISO 15924 code) See also * Limb darkening Limb darkening is an optical effect s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic. The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it was well into the middle of the Triassic before life recovered its former diversity. Three categories of organisms can be distinguished in the Triassic record: survivors from the extinction event, new groups that flourished briefly, and other new groups that went on to dominate the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized subgroup of archo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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