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Trionychid
Trionychidae is a family of turtles, commonly known as softshell turtles or simply softshells. The family was described by Leopold Fitzinger in 1826. Softshells include some of the world's largest freshwater turtles, though many can adapt to living in highly brackish waters. Members of this family occur in Africa, Asia, and North America, with extinct species known from Australia. Most species have traditionally been included in the genus ''Trionyx'', but the vast majority have since been moved to other genera. Among these are the North American ''Apalone'' softshells that were placed in ''Trionyx'' until 1987. Characteristics Turtles of the family Trionychidae are called "softshell" because their carapaces lack horny scutes (scales), though the spiny softshell, '' Apalone spinifera'', does have some scale-like projections, to which its common name refers. The carapace is leathery and pliable, particularly at the sides. The central part of the carapace has a layer of solid bone b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plastomeninae
Plastomeninae is an Extinction, extinct subfamily of Trionychidae, softshell turtles that inhabited most of North America from the Cretaceous to the Eocene. Members of this subfamily are also known as plastomenines. Taxonomy and evolution They are thought to have originated in North America during or shortly before the Campanian from basal Trionychidae, trionychids that dispersed from Asia. They reached their peak diversity from the Maastrichtian through the Paleocene, having survived the Cretaceous–Paleogene extinction event. However, they went entirely extinct by the Lutetian. The last surviving member of this subfamily is thought to have been ''Plastomenus thomasii'', which is the only known member of the subfamily to have survived past the Paleocene into the Eocene. Morphological analysis supports them being the Sister group, sister taxon to the Cyclanorbinae, flapshell turtles (subfamily Cyclanorbinae), which still survive to the present day in parts of tropical Asia an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trionyx
''Trionyx'' is a genus of softshell turtles belonging to the family Trionychidae. In the past many species in the family were classified in this genus, but today '' T. triunguis'', the African or Nile softshell turtle, is the only extant softshell still classified as ''Trionyx''. The other species still assigned to this genus are only known from fossils. ''T. triunguis'' is a relatively large, aquatic piscivore. Species The list of species follows a 2017 review of the Trionychidae by Georgios L. Georgalis and Walter G. Joyce. * '' Trionyx triunguis'' ( Forsskål, 1775) – African or Nile softshell turtle * † '' Trionyx pliocenicus'' Fucini, 1912 – Pliocene of Tuscany (Italy) * † '' Trionyx vindobonensis'' (Peters, 1855) – Miocene of Vienna (Austria) The following species are considered valid trionychid taxa, but with uncertain phylogenetic relationships. They are only referred to ''Trionyx'' provisionally due to its historic status as a wastebasket taxon Wasteba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclanorbinae
Cyclanorbinae, also known commonly as the flapshell turtles, is a subfamily of softshell turtles in the family Trionychidae. The subfamily is native to Africa and Asia. Taxonomy Morphological evidence supports Cyclanorbinae being the sister group to the Plastomeninae, an extinct subfamily of softshell turtles that inhabited North America from the Cretaceous to the Eocene. Genera The subfamily Cyclanorbinae contains the following three extant genera.Turtle Taxonomy Working Group (Rhodin, Anders G.J.; Parham, James F.; van Dijk, Peter Paul; Iverson, John B.) (2009"Turtles of the World: Annotated Checklist of Taxonomy and Synonymy, 2009 Update". ''Chelonian Research Monographs'' (5): 000.39-000.84. (Cyclanorbinae, pp. 000.55-000.56). *'' Cyclanorbis'' *'' Cycloderma'' *''Lissemys'' One extinct prehistoric genus is also known from fossil remains: '' Nemegtemys'' , from the Cretaceous of Mongolia. Geographic range Species A species () is often defined as the largest gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trionychinae
The Trionychinae are a subfamily of turtles in the family Trionychidae. Classification The subfamily has 11 extant genera: *''Amyda'' *''Apalone'' *''Axestemys'' *''Chitra (turtle), Chitra'' *''Dogania'' *''Drazinderetes'' *''Gobiapalone'' *''Khunnuchelys'' *''Murgonemys'' *''Nilssonia (turtle), Nilssonia'' *''Oliveremys'' *''Palea (turtle), Palea'' *''Palaeoamyda'' *''Pelochelys'' *''Pelodiscus'' *''Rafetoides'' (nomen dubium) *''Rafetus'' *''Trionyx'' References {{Taxonbar, from=Q2036081 Trionychinae, Reptile subfamilies Taxa named by John Edward Gray ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelodiscus Sinensis
The Chinese softshell turtle (''Pelodiscus sinensis'') is a species of softshell turtle that is native to mainland China (Inner Mongolia to Guangxi, including Hong Kong) and Taiwan, with records of escapees—some of which have established Introduced species, introduced populations—in a wide range of other Asian countries, as well as Spain, Brazil and Hawaii. Populations native to Northeast China, Russia, Korea and Japan were formerly included in this species, but are now regarded as separate as the northern Chinese softshell turtle (''P. maackii''). Furthermore, localized populations in Guangxi and Hunan (where the Chinese softshell turtle also is present), as well as Vietnam, are recognized as the lesser Chinese softshell turtle (''P. parviformis'') and Hunan softshell turtle (''P. axenaria''). The Chinese softshell turtle is a vulnerable species, threatened by disease, habitat loss, and collection for food such as turtle soup. Additionally, millions are now Turtle farming, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urea
Urea, also called carbamide (because it is a diamide of carbonic acid), is an organic compound with chemical formula . This amide has two Amine, amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important role in the cellular metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. ''Urea'' is Neo-Latin, , , itself from Proto-Indo-European ''*h₂worsom''. It is a colorless, odorless solid, highly soluble in water, and practically non-toxic ( is 15 g/kg for rats). Dissolved in water, it is neither acidic nor base (chemistry), alkaline. The body uses it in many processes, most notably metabolic waste#Nitrogen wastes, nitrogen excretion. The liver forms it by combining two ammonia molecules () with a carbon dioxide () molecule in the urea cycle. Urea is widely used in fertilizers as a source of nitrogen (N) and is an important ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raymond Ditmars
Raymond Lee Ditmars (June 22, 1876 – May 12, 1942) was an American herpetology, herpetologist, writer, public speaker and pioneering natural history filmmaker. Biography Ditmars was fascinated by all animals, but primarily reptiles, obtaining his first snakes at twelve years of age. His parents eventually allowed him to keep all manner of venomous reptiles in the attic of their house at 1666 Bathgate Avenue in the Bronx. Ditmars left school at 16 with no formal qualifications but nevertheless gained a deep understanding of zoology through his own personal study of snakes and other animals in the wild and captivity. Throughout his life, vacations were spent searching for new specimens. Such was his interest and knowledge that he would eventually be regarded as the country's foremost herpetologist. In 1893, Ditmars was hired as an assistant in the department of entomology at the American Museum of Natural History, primarily because of his talent as an artist. Four years lat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature-dependent Sex Determination
Temperature-dependent sex determination (TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larval development determine the sex of the offspring. It is observed in reptiles and teleost fish, with some reports of it occurring in species of shrimp. TSD differs from the chromosomal sex-determination systems common among vertebrates. It is the most studied type of environmental sex determination (ESD). Some other conditions, e.g. density, pH, and environmental background color, are also observed to alter sex ratio, which could be classified either as temperature-dependent sex determination or temperature-dependent sex differentiation, depending on the involved mechanisms. As sex-determining mechanisms, TSD and genetic sex determination (GSD) should be considered in an equivalent manner, which can lead to reconsidering the status of fish species that are claimed to have TSD when submitted to extreme temperatures instead of the temp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ZW Sex-determination System
The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), the schistosome family of flatworms, and some reptiles, e.g. majority of snakes, lacertid lizards and monitors, including Komodo dragons. It is also present in some plants, where it has evolved independently on many occasions, characterizing at least 22% of plants with documented sex chromosomes. The letters Z and W are used to distinguish this system from the XY sex-determination system. In the ZW system, females have a pair of dissimilar ZW chromosomes, and males have two similar ZZ chromosomes. In contrast to the XY sex-determination system and the X0 sex-determination system, where the sperm determines the sex, in the ZW system, the ovum determines the sex of the offspring. Males are the homogametic sex (ZZ), while females are the heterogametic sex (ZW). The Z ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microchromosome
A microchromosome is a chromosome defined for its relatively small size. They are typical components of the karyotype of birds, some reptiles, fish, amphibians, and monotremes. As many bird genomes have chromosomes of widely different lengths, the name was meant to distinguish them from the comparatively large macrochromosomes. The distinction referred to the measured size of the chromosome while staining for karyotype, and while there is not a strict definition, chromosomes resembling the large chromosomes of mammals were called macrochromosomes (roughly 3 to 6 μm), while the much smaller ones of less than around 0.5 μm were called microchromosomes. In terms of base pairs, by convention, those of less than 20Mb were called microchromosomes, those between 20 and 40 Mb are classified as intermediate chromosomes, and those larger than 40Mb are macrochromosomes. By this definition, all normal chromosomes in organisms with relatively small genomes (less than 100-200Mb) wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
