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Sichuanchelyidae
Sichuanchelyidae is a family of extinct turtles in the clade Testudinata. It includes all perichelydians that are more closely related to '' Sichuanchelys'' than '' Meiolania'', '' Helochelydra'', or any extant turtles. Systematics The family Sichuanchelyidae was originally created to accommodate the Middle Jurassic Chinese turtle '' Sichuanchelys'', and it was considered monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ... until Joyce et al. (2016) recovered the problematic Late Cretaceous turtle '' Mongolochelys'' from Mongolia as a close relative of ''Sichuanchelys''. The late Paleocene form '' Laurasichersis'' from Europe is the youngest sichuanchelyid, showing that stem turtles in Laurasia outlived the Mesozoic. References Extinct turtles Testudinata Prehisto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perichelydia
Perichelydia (from Greek ''peri'' "near" and ''chelys'' "turtle") is a clade within Pantestudines (turtles and their extinct relatives) known from the Middle Jurassic to Holocene. Alongside crown group Testudines, it also contains Helochelydridae, which is known from the Cretaceous of Europe and North America, Sichuanchelyidae from the Middle Jurassic to Paleocene of Asia and Europe, Meiolaniformes, which is known from the Cretaceous to Holocene of South America, Australia and Oceania, and '' Spoochelys'', known from the Mid-Cretaceous Griman Creek Formation of Australia. ''Kallokibotion'' from the Late Cretaceous of Europe is also considered part of this group. Several other groups, including the proposed clade Angolachelonia (containing Thalassochelydia and Sandownidae), Paracryptodira, Macrobaenidae, Sinemydidae and Xinjiangchelyidae, which are sometimes considered members of Cryptodira, have also been found outside crown Testudines in several analyses. These groups are usually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus comes above species and below family (taxonomy), family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turtle
Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked turtles), which differ in the way the head retracts. There are 360 living and recently extinct species of turtles, including land-dwelling tortoises and freshwater terrapins. They are found on most continents, some islands and, in the case of sea turtles, much of the ocean. Like other amniotes (reptiles, birds, and mammals) they breathe air and do not lay eggs underwater, although many species live in or around water. Turtle shells are made mostly of bone; the upper part is the domed carapace, while the underside is the flatter plastron or belly-plate. Its outer surface is covered in scales made of keratin, the material of hair, horns, and claws. The carapace bones develop from ribs that grow sideways and develop into broad flat plates th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testudinata
Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles). Though it was first coined as the group containing turtles by Jacob Theodor Klein in 1760, it was first defined in the modern sense by Joyce and colleagues in 2004. Testudinata does not include the primitive stem-turtle ''Odontochelys'', which only had the bottom half of a shell. A recent phylogenetic tree of Testudinata included Angolachelonia and Testudines Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ... as sister-taxa and subgroups of Testudinata. Classification The cladogram below follows an analysis by Jérémy Anquetin in 2012. References {{Taxonbar, from=Q16114972 Reptile taxonomy Norian f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meiolania
''Meiolania'' ("small roamer") is an extinct genus of meiolaniid stem-turtle native to Australasia from the Middle Miocene to Late Pleistocene and possibly Holocene. It is best known from fossils found on Lord Howe Island, though fossils are known from mainland Australia, New Caledonia, and possibly Vanuatu and Fiji. Taxonomy The genus was erected in 1886 based on remains found on Lord Howe Island, which Richard Owen assigned to the two species ''M. platyceps'' and ''M. minor'' (now a synonym of the former). These were the first good meiolaniid remains, and were used to show that the first known remains of a related animal, a species from Queensland now known as '' Ninjemys oweni'' (which was assigned to ''Meiolania'' until 1992), did not belong to lizards as initially thought, but to turtles. Woodward sank ''Niolamia argentina'' into ''Meiolania'', but this was not accepted by later authors. The species of the genus may be summarized as In New Caledonia, ''M. mackayi'' was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helochelydra
''Helochelydra'' is an extinct genus of extinct stem turtle known from the Early Cretaceous (Barremian) of the Isle of Wight, southern England. Phylogeny ''Helochelydra'' is a member of the stem turtle family Helochelydridae, which is known from Late Jurassic to Late Cretaceous deposits in North America and Europe. Cladistic analysis recovers Helochelydridae outside the clade leading to crown turtles (Testudines).W. G. Joyce, S. D. Chapman, R. T. J. Moody, C. A. Walker (2011) The skull of the solemydid turtle ''Helochelydra nopcsai'' from the Early Cretaceous of the Isle of Wight (UK) and a review of Solemydidae. ''Special Papers in Palaeontology'': 75-97. Taxonomy ''Helochelydra'' was named in 1928 by Franz Baron Nopcsa for a partial shell ( NHMUK R171) from the Early Cretaceous Wessex Formation of the Isle of Wight that Lydekker (1889) had referred to ''Tretosternon punctatum'', a turtle taxon from the Purbeck Group of Dorset, but no species name was provided. Lapparent de Bro ... [...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 Mya. The Jurassic constitutes the middle period of the Mesozoic, Mesozoic Era 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. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread Anoxic event, oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar, Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotypic Taxon
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. In contrast, an oligotypic taxon contains more than one but only a very few subordinate taxa. Examples Just as the term ''monotypic'' is used to describe a taxon including only one subdivision, the contained taxon can also be referred to as monotypic within the higher-level taxon, e.g. a genus monotypic within a family. Some examples of monotypic groups are: Plants * In the order Amborellales, there is only one family, Amborellaceae and there is only one genus, '' Amborella'', and in this genus there is only one species, namely ''Amborella trichopoda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinct Turtles
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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