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Siamotyrannus Isanensis
''Siamotyrannus'' (meaning "Siamese tyrant") is a genus of theropod dinosaur from the early Cretaceous of Thailand. Discovery and naming In 1993, Somchai Traimwichanon found a partial skeleton of a large theropod at the Phu Wiang 9 site in Khon Kaen. In 1996, Eric Buffetaut, Varavudh Suteethorn and Haiyan Tong named and described the type species ''Siamotyrannus isanensis''. The generic name is derived from the old Thai kingdom of Siam, and a Latinised Greek ''tyrannus'', meaning "tyrant", in reference to a presumed membership of the Tyrannosauridae. The specific name is derived from Thai ''isan'', "northeastern part", referring to the provenance from northeast Thailand. The holotype, PW9-1, was found in the Sao Khua Formation, dating from the Berriasian-Barremian. It includes the left half of the pelvis, five rear dorsal vertebrae, the sacrum with five sacrals, and thirteen front tail vertebrae. In 1998, a tibia and some individual teeth were referred to the species. Descri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java-Manihiki-Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km2. In the Indian Ocean another LIP began to form at c. 120 Ma, the Kerguelen P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berriasian
In the geological timescale, the Berriasian is an age/stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years ago). The Berriasian succeeds the Tithonian (part of the Jurassic) and precedes the Valanginian. Stratigraphic definition The Berriasian Stage was introduced in scientific literature by Henri Coquand in 1869. It is named after the village of Berrias in the Ardèche department of France. The largely non-marine English Purbeck Formation is in part of Berriasian age.In fact, the first rocks to be described of this age were the beds of the English Purbeck Formation, named as the Purbeckian by Alexandre Brongniart in 1829 following description by Henry De la Beche, William Buckland, Thomas Webster and William Henry Fitton. The base of the Berriasian, which is also the base of the Cretaceous System, has traditionally been placed at the first ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinraptorid
Metriacanthosauridae is an extinct family of allosauroid theropod dinosaurs that lived from the Middle Jurassic to the Early Cretaceous. When broken down into its Greek roots, it means "moderately-spined lizards". The family is split into two subgroups: Metriacanthosaurinae, which includes dinosaurs closely related to ''Metriacanthosaurus'', and another group composed of the close relatives of ''Yangchuanosaurus''. Metriacanthosaurids are considered carnosaurs, belonging to the Allosauroidea superfamily. The group includes species of large range in body size. Of their physical traits, most notable are their neural spines.Bailey, Jack Bowman. "Neural Spine Elongation in Dinosaurs: Sailbacks or Buffalo-Backs?" Journal of Paleontology, vol. 71, no. 06, 1997, pp. 1124–1146., doi:10.1017/s0022336000036076. The records of the group are mostly confined to Asia, though ''Metriacanthosaurus'' is known from Europe. Metriacanthosauridae is used as a senior synonym of Sinraptoridae. Diagno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allosaurid
Allosauridae is a family of medium to large bipedal, carnivorous allosauroid theropod dinosaurs from the Late Jurassic. Allosauridae is a fairly old taxonomic group, having been first named by the American paleontologist Othniel Charles Marsh in 1878. Allosaurids are characterized by an astragalus with a restriction of the ascending process to the lateral part of the bone, a larger medial than lateral condyle, and a horizontal groove across the face of the condyles. Description Allosaurids have a general anatomy typical of other neotheropod dinosaurs, contributing to the difficulty in defining the family's membership. A typical 8m specimen of ''Allosaurus fragilis'' had a skull of about 0.85m. The premaxilla has five teeth and the maxilla usually around 16. The dentary also typically has 16 teeth. All teeth are serrated and continuously replaced throughout the life of the animal. Allosaurid skulls are characterized by two sets of crests formed by the nasal and lacrimal bones res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnosaur
Carnosauria is an extinct large group of predatory dinosaurs that lived during the Jurassic and Cretaceous periods. Starting from the 1990s, scientists have discovered some very large carnosaurs in the carcharodontosaurid family, such as ''Giganotosaurus'', ''Mapusaurus'', ''Carcharodontosaurus'' and ''Tyrannotitan'' which are among the largest known predatory dinosaurs. While it originally contained a wide assortment of giant theropods that were not closely related, the group has since been defined to encompass only the allosaurs and their closest kin. However, with the description and publication in 2019 of '' Asfaltovenator vialidadi'', a basal allosauroid curiously displaying both primitive and derived features seen in Tetanurae, the new phylogenetic analysis has found Megalosauroidea to be a basal grade of carnosaurs in respect to Allosauroidea; thus significantly expanding Carnosauria's inclusiveness towards its original context. Distinctive characteristics of carnosaur ... [...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] |
Synapomorphies
In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have evolved in their most recent common ancestor. ) In cladistics, synapomorphy implies homology. Examples of apomorphy are the presence of erect gait, fur, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a sprawling gait and lack of fur. Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals. Etymology The word —coined by German entomologist Willi Hennig—is derived from the Ancient Greek words (''sún''), meaning "with, together"; (''apó''), meaning "away from"; and (''morphḗ''), meaning "shape, form". Clade analysis T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrannosaurid
Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera is controversial, with some experts recognizing as few as three. All of these animals lived near the end of the Cretaceous Period and their fossils have been found only in North America and Asia. Although descended from smaller ancestors, tyrannosaurids were almost always the largest predators in their respective ecosystems, putting them at the apex of the food chain. The largest species was ''Tyrannosaurus rex'', one of the largest and most massive known land predators, which measured over in length and according to most modern estimates to in weight. Tyrannosaurids were bipedal carnivores with massive skulls filled with large teeth. Despite their large size, their legs were long and proportioned for fast movement. In contrast, their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrannosauroid
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Jurassic Period. By the end of the Cretaceous Period, tyrannosauroids were the dominant large predators in the Northern Hemisphere, culminating in the gigantic ''Tyrannosaurus''. Fossils of tyrannosauroids have been recovered on what are now the continents of North America, Europe and Asia, with fragmentary remains possibly attributable to tyrannosaurs also known from South America and Australia. Tyrannosauroids were bipedal carnivores, as were most theropods, and were characterized by numerous skeletal features, especially of the skull and pelvis. Early in their existence, tyrannosauroids were small predators with long, three-fingered forelimbs. Late Cretaceous genera became much larger, including some of the largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autapomorphy
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to the focal taxon (which may be a species, family or in general any clade). It can therefore be considered an apomorphy in relation to a single taxon. The word ''autapomorphy'', first introduced in 1950 by German entomologist Willi Hennig, is derived from the Greek words αὐτός, ''autos'' "self"; ἀπό, ''apo'' "away from"; and μορφή, ''morphḗ'' = "shape". Discussion Because autapomorphies are only present in a single taxon, they do not convey information about relationship. Therefore, autapomorphies are not useful to infer phylogenetic relationships. However, autapomorphy, like synapomorphy and plesiomorphy is a relative concept depending on the taxon in question. An autapomorphy at a given level may well be a synapomorphy at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gregory S
Gregory may refer to: People and fictional characters * Gregory (given name), including a list of people and fictional characters with the given name * Gregory (surname), a surname Places Australia *Gregory, Queensland, a town in the Shire of Burke **Electoral district of Gregory, Queensland, Australia *Gregory, Western Australia. United States *Gregory, South Dakota *Gregory, Tennessee *Gregory, Texas Outer space *Gregory (lunar crater) *Gregory (crater on Venus) Other uses * "Gregory" (''The Americans''), the third episode of the first season of the television series ''The Americans'' See also * Greg (other) * Greggory * Gregoire (other) * Gregor (other) * Gregores (other) * Gregorian (other) * Gregory County (other) * Gregory Highway, Queensland * Gregory National Park, Northern Territory * Gregory River in the Shire of Burke, Queensland * Justice Gregory (other) Justice Gregory may refer to: * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones. The two projections at the sides of the sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua. The sacrum has three different surfaces which are shaped to accommodate surrounding pelvic structures. Overall it is concave (curved upon itself). The base of the sacrum, the broadest and uppermost part, is tilted forward as the sacral promontory internally. The central part is curved outward toward the posterior, allowing greater room for the pel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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