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Clevosauridae
Clevosaurs are an extinct group of rhynchocephalian reptiles from the Triassic and Jurassic periods. History and definition Although members of this group have been known since 1910, only recently has the group received a formal name. In the late 1990s, Victor-Hugo Reynoso established that three particular genera of Sphenodontia (''Clevosaurus, Brachyrhinodon'', and ''Polysphenodon'') were closely related to each other. He gave the informal name "clevosaurs" to these three genera, after the most numerous and well-known genus, ''Clevosaurus.'' He considered clevosaurs to be members of the family Sphenodontidae, the family of rhynchocephalians containing the only living member of the order, the tuatara (''Sphenodon).'' In 2006, Bonaparte and Sues finally gave "clevosaurs" a formal name and taxonomic rank as the family Clevosauridae. They defined Clevosauridae as the last common ancestor of ''Clevosaurus, Brachyrhinodon,'' and ''Polysphenodon,'' and all of its descendants. In 201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clevosauridae
Clevosaurs are an extinct group of rhynchocephalian reptiles from the Triassic and Jurassic periods. History and definition Although members of this group have been known since 1910, only recently has the group received a formal name. In the late 1990s, Victor-Hugo Reynoso established that three particular genera of Sphenodontia (''Clevosaurus, Brachyrhinodon'', and ''Polysphenodon'') were closely related to each other. He gave the informal name "clevosaurs" to these three genera, after the most numerous and well-known genus, ''Clevosaurus.'' He considered clevosaurs to be members of the family Sphenodontidae, the family of rhynchocephalians containing the only living member of the order, the tuatara (''Sphenodon).'' In 2006, Bonaparte and Sues finally gave "clevosaurs" a formal name and taxonomic rank as the family Clevosauridae. They defined Clevosauridae as the last common ancestor of ''Clevosaurus, Brachyrhinodon,'' and ''Polysphenodon,'' and all of its descendants. In 201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clevosaurus
''Clevosaurus'' (meaning "Gloucester lizard") is an extinct genus of rhynchocephalian reptile from the Late Triassic and the Early Jurassic periods. Species of ''Clevosaurus'' were widespread across Pangaea, and have been found on all continents except Australia and Antarctica. Five species of ''Clevosaurus'' have been found in ancient fissure fill deposits in south-west England and Wales, alongside other sphenodontians, early mammals and dinosaurs. In regards to its Pangaean distribution, ''C. hadroprodon'' is the oldest record of a sphenodontian from Gondwana, though its affinity to ''Clevosaurus'' has been questioned. History of discovery The first species of ''Clevosaurus'' to be described was ''C. hudsoni'', which was described by William Elgin Swinton in 1939 from a fissure fill deposit in Cromhall Quarry ( Magnesian Conglomerate Formation) in the county of Gloucestershire, England, with the name of the county lending its name to the genus. Description ''Clevosaurus' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clevosaurus Brasiliensis
''Clevosaurus'' (meaning "Gloucester lizard") is an extinct genus of rhynchocephalian reptile from the Late Triassic and the Early Jurassic periods. Species of ''Clevosaurus'' were widespread across Pangaea, and have been found on all continents except Australia and Antarctica. Five species of ''Clevosaurus'' have been found in ancient fissure fill deposits in south-west England and Wales, alongside other sphenodontians, early mammals and dinosaurs. In regards to its Pangaean distribution, ''C. hadroprodon'' is the oldest record of a sphenodontian from Gondwana, though its affinity to ''Clevosaurus'' has been questioned. History of discovery The first species of ''Clevosaurus'' to be described was ''C. hudsoni'', which was described by William Elgin Swinton in 1939 from a fissure fill deposit in Cromhall Quarry ( Magnesian Conglomerate Formation) in the county of Gloucestershire, England, with the name of the county lending its name to the genus. Description ''Clevosaurus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachyrhinodon Taylori
''Brachyrhinodon'' (meaning "short nose tooth") is an extinct genus of sphenodontian from the Late Triassic Lossiemouth Sandstone of Scotland. It is related to the tuatara, the only member of its order that is not extinct. ''Brachyrhinodon'' is known from the sandstone quarries near Elgin, and is one of the Elgin Reptiles. Sources * ''Vertebrate Palaeontology'' by Michael J. Benton * ''In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods'' by Nicholas C. Fraser and Hans-Dieter Sues Hans-Dieter Sues (born January 13, 1956) is a German-born American paleontologist who is Senior Scientist and Curator of Vertebrate Paleontology at the National Museum of Natural History of the Smithsonian Institution in Washington, DC. He receiv ... *''The Beginning of the Age of Dinosaurs: Faunal Change across the Triassic-Jurassic Boundary'' by Kevin Padian Triassic lepidosaurs Triassic reptiles of Europe Sphenodontia Prehistoric reptile genera {{triassic-reptile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opisthodontia (rhynchocephalians)
Opisthodontia is a proposed clade of sphenodontian reptiles, uniting ''Opisthias'' from the Late Jurassic-earliest Cretaceous of Europe and North America with the Elienodontinae, a group of herbivorous sphenodontians known from the Late Triassic to Late Cretaceous. Description Teeth and diet Like other sphenodonts, opisthodonts had acrodont teeth which grew directly from the bone. They had one row of teeth on the lower jaw and two rows on the roof of the mouth. When processing food, their mandibular teeth would have slid between the outer (maxillary) teeth and inner (palatine) teeth. Some opisthodonts, such as '' Sphenotitan'', also had clusters of small teeth on the pterygoid at the center of the mouth roof. Opisthodont teeth were wide, numerous, and tightly-packed for grinding and shredding tough plant matter. Although wide shredding teeth are also known in a few other sphenodontians, such as ''Clevosaurus'' and ''Pelecymala'', the most diverse and long-lasting group of he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachyrhinodon
''Brachyrhinodon'' (meaning "short nose tooth") is an extinct genus of sphenodontian from the Late Triassic Lossiemouth Sandstone of Scotland. It is related to the tuatara, the only member of its order that is not extinct. ''Brachyrhinodon'' is known from the sandstone quarries near Elgin, and is one of the Elgin Reptiles. Sources * ''Vertebrate Palaeontology'' by Michael J. Benton * ''In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods'' by Nicholas C. Fraser and Hans-Dieter Sues Hans-Dieter Sues (born January 13, 1956) is a German-born American paleontologist who is Senior Scientist and Curator of Vertebrate Paleontology at the National Museum of Natural History of the Smithsonian Institution in Washington, DC. He receiv ... *''The Beginning of the Age of Dinosaurs: Faunal Change across the Triassic-Jurassic Boundary'' by Kevin Padian Triassic lepidosaurs Triassic reptiles of Europe Sphenodontia Prehistoric reptile genera {{triassic-reptile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhynchocephalia
Rhynchocephalia (; ) is an order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a diverse group including a wide array of morphologically distinct forms. The oldest record of the group is dated to the Middle Triassic around 238 to 240 million years ago, and they had achieved a worldwide distribution by the Early Jurassic. Most rhynchocephalians belong to the group Sphenodontia ('wedge-teeth'). Their closest living relatives are lizards and snakes in the order Squamata, with the two orders being grouped together in the superorder Lepidosauria. Many of the niches occupied by lizards today were held by sphenodontians during the Triassic and Jurassic, although lizard diversity began to overtake sphenodontian diversity in the Cretaceous, and they had disappeared almost entirely by the beginning of the Cenozoic. While the modern tuat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxillary bones are fused at the intermaxillary suture, forming the anterior nasal spine. This is similar to the mandible (lower jaw), which is also a fusion of two mandibular bones at the mandibular symphysis. The mandible is the movable part of the jaw. Structure In humans, the maxilla consists of: * The body of the maxilla * Four processes ** the zygomatic process ** the frontal process of maxilla ** the alveolar process ** the palatine process * three surfaces – anterior, posterior, medial * the Infraorbital foramen * the maxillary sinus * the incisive foramen Articulations Each maxilla articulates with nine bones: * two of the cranium: the frontal and ethmoid * seven of the face: the nasal, zygomatic, lacrimal, inferior n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Taxon
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 taxonomi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polysphenodon
''Polysphenodon'' is an extinct genus of clevosaurine reptile from the Late Triassic Keuper Group of Germany,N. C. Fraser and M. J. Benton. (1989) The Triassic reptiles ''Brachyrhinodon'' and ''Polysphenodon'' and the relationships of the sphenodontids. ''Zoological Journal of the Linnean Society'' 96:413-445 discovered within a borehole at below the surface. The type species, ''P. mulleri'', was described by Otto Jaekel in 1911.Jaekel, O (1911) Die Wierbeltiere. Eine Übersicht über diefossilen und lebenden Formen. ''Borntraeger, Berlin'', 252p The limbs of ''Polysphenodon'' are long relative to the size of the skull and are similar in proportions to some species of ''Homoeosaurus ''Homoeosaurus'' is an extinct genus of sphenodont reptile. It was found in limestone in Bavaria, Germany, as well as in France and the United Kingdom. It was related to the modern tuatara, though it was a considerably more gracile. There were se ...''. This resemblance is considered to be indi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic Analysis
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the "end" or the present time in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the tree. An unrooted tree diagram (a network) makes no assumption about the ancestral line, and does n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to descendants, nor does it show how much they have changed, so many differing evolutionary trees can be consistent with the same cladogram. A cladogram uses lines that branch off in different directions ending at a clade, a group of organisms with a last common ancestor. There are many shapes of cladograms but they all have lines that branch off from other lines. The lines can be traced back to where they branch off. These branching off points represent a hypothetical ancestor (not an actual entity) which can be inferred to exhibit the traits shared among the terminal taxa above it. This hypothetical ancestor might then provide clues about the order of evolution of various features, adaptation, and other evolutionary narratives about ance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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