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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 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 Prehistoric turtles Testudinata † A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species or languages). It is one of the mo ... [...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 us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. 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 of an ancestral taxon are grouped together (i.e. Phylogeneti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laurasichersis
''Laurasichersis'' is an extinct genus of turtle that lived in France during the Thanetian stage. It is known from a single species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ..., ''L. relicta''. References Testudinata Prehistoric turtle genera {{Paleo-turtle-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turtle
Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, 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 Amniote, 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 Turtle shell#Carapace, carapace, while the underside is the flatter plastron or belly-plate. Its outer surface is covered in scale (anatomy), scales made of keratin, the material of hair, horns, and claws. The carapace bones deve ... [...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 excluding ''Odontochelys'' and ''Eorhynchochelys,'' which are placed in the more inclusive Pantestudines''.'' History It was first coined as the group containing turtles by Jacob Theodor Klein in 1760. In 1832-1836, Thomas Bell (zoologist), Thomas Bell wrote a book describing the Testudinata, which summarizes all the world's turtles, living and extinct, illustrated by forty plates by Jane S. Bell, James de Carle Sowerby and Edward Lear. It was first defined in the modern sense by Joyce and colleagues in 2004. While the ancestral condition for the clade is thought to be terrestrial, members of the subclade Mesochelydia, which contains almost all known testudinatans from the Jurassic onwards, are thought to be ancestrally aquatic. Classification The cladogram below follows an analysis by Jérémy A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meiolania
''Meiolania'' is an extinct genus of meiolaniid stem-turtle native to Australasia throughout much of the Cenozoic. ''Meiolania'' was a large turtle, with the shell alone ranging from in length. Four species are currently recognized, although the validity of two of them is disputed. ''Meiolania'' was first described as a species of lizard related to '' Megalania'' by Richard Owen towards the end of the 19th century, before the continued discovery of additional fossils solidified its placement as a kind of turtle. The best known species is ''M. platyceps'', known from hundreds of specimens collected in Pleistocene strata of Lord Howe Island. The oldest known species is ''M. brevicollis'' from the Miocene of mainland Australia. Other species include ''M. mackayi'' from Pleistocene New Caledonia, which may be synonymous with ''M. platyceps'', ''? M. damelipi'' from Holocene Vanuatu, which may represent a non-meiolaniid turtle, and the Wyandotte species, an unnamed form from Pleistoce ... [...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 Br ... [...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] |
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 Genus, 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. Theoretical implications Monotypic taxa present several important theoretical challenges in biological classification. One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in a hierarchical o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Turtles
Prehistory, also called pre-literary history, is the period of human history between the first known use of stone tools by hominins million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared years ago. It took thousands of years for writing systems to be widely adopted, with writing having spread to almost all cultures by the 19th century. The end of prehistory therefore came at different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. It is based on an old conception of history that without written records there could be no history. The most common conception today is that history is based on evidence, however the concept of prehistory hasn't been completely discarded. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
