|
Clevosauridae
Clevosaurs are an Extinction, 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 (biology), family Clevosauridae. They defined Clevosauridae as the last common ancestor of ''Clevosaurus, Brachyrhinodon,'' and ''Polysphenodon,'' and ... [...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. Another notable specimen was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polysphenodon
''Polysphenodon'' is an extinct genus of sphenodontian reptile with a single species ''Polysphenodon mulleri'' 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 History of discovery The genus and only known species ''Polysphenodon mulleri'' was described by Otto Jaekel in 1911''.Jaekel, O (1911) Die Wierbeltiere. Eine Übersicht über diefossilen und lebenden Formen. ''Borntraeger, Berlin'', 252p Polysphenodon mulleri'' is known from a single partial skeleton recovered from a borehole sample at depth, which includes parts of the skull, limbs and tail vertebrae. This specimen has been lost since the 1930s, but is known from several casts. Description The skull was around long in life. The snout is relatively short, even when accounting for post-mortem distortion. The limbs ... [...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 speciose group with high morphological and ecological diversity. The oldest record of the group is dated to the Middle Triassic around 238 to 240 million years ago, and they had achieved global 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. Rhynchocephalians are distinguished from squamates by a number of traits, including the retention of rib-like gastralia bones in the belly, as well as most rhynchocephalians having acrodont teeth that are fused to the crests of the jaws (the latter also found among a small number of modern lizard grou ... [...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. History of discovery ''Brachyrhinodon'' and its single species ''B. taylori'' originally described in 1910 by German paleontologist Friedrich von Huene based on three specimens found near Elgin, Scotland where a number of reptile fossils (collectively dubbed the " Elgin Reptiles") have been found. The species was later redescribed in 1989 based on 12 specimens, representing at least 10 individuals. The specimens are largely preserved as negative moulds within the sandstone, which meant that casts needed to be made for description. Description ''Brachyrhinodon'' is known from remains covering most of the skeleton. The skull of ''Brachyrhinodon'' is around long. The skull is relatively blunt. The front of the upper jaw overhangs the front of the lower jaw. The teeth are conical. The postcranial skeleton is similar to that of other ... [...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 Eilenodontinae, 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 bone, palatine) teeth. Some opisthodonts, such as ''Sphenotitan'', also had clusters of small teeth on the Pterygoid bone, 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 divers ... [...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. History of discovery ''Brachyrhinodon'' and its single species ''B. taylori'' originally described in 1910 by German paleontologist Friedrich von Huene based on three specimens found near Elgin, Scotland where a number of reptile fossils (collectively dubbed the " Elgin Reptiles") have been found. The species was later redescribed in 1989 based on 12 specimens, representing at least 10 individuals. The specimens are largely preserved as negative moulds within the sandstone, which meant that casts needed to be made for description. Description ''Brachyrhinodon'' is known from remains covering most of the skeleton. The skull of ''Brachyrhinodon'' is around long. The skull is relatively blunt. The front of the upper jaw overhangs the front of the lower jaw. The teeth are conical. The postcranial skeleton is similar to that of other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. The Jurassic constitutes the second and middle period of the Mesozoic, Mesozoic Era as well as the eighth period of the Phanerozoic, Phanerozoic Eon and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province (CAMP). The beginning of the Toarcian Age started around 183 million years ago and is marked by the Toarcian Oceanic Anoxic Event, a global episode of Anoxic event, oceanic anoxia, ocean acidification, and elevated global temperatures associated with extinctions, likely caused by the eruption of the Kar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pterygoid Bone
The pterygoid is a paired bone forming part of the palate of many vertebrates, behind the palatine bone In anatomy, the palatine bones (; derived from the Latin ''palatum'') are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxilla, they comprise the hard palate. Stru ...s. It is a flat and thin lamina, united to the medial side of the pterygoid process of the sphenoid bone, and to the perpendicular lamina of the palatine bone. References Bones of the head and neck {{musculoskeletal-stub ... [...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 taxonomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and recover. As a species' potential Range (biology), range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxon, Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the Fossil, fossil record) after a period of apparent absence. Over five billion species are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryotes globally, possibly many times more if microorganisms are included. Notable extinct animal species include Dinosaur, non-avian dinosaurs, Machairodontinae, saber-toothed cats, and mammoths. Through evolution, species arise through the process of specia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
