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Aenigmastacus
''Aenigmastacus crandalli'' is a species of fossil freshwater crayfish. It was found in early Eocene Okanagan Highlands lake deposits in British Columbia, and was described in 2011. It is the first member of the Gondwana-distributed family Parastacidae to be found in the Northern Hemisphere, and is the only species in the genus ''Aenigmastacus''. Twelve specimens are known, with a total body length of . On some specimens, details of the internal anatomy can be seen due to the exceptional preservation. Origin and description ''Aenigmastacus'' was discovered in the Tranquille Formations McAbee Fossil Beds of British Columbia, Canada,Feldmann ''et al.'' (2011), p. 320 at . The McAbee beds comprise a thickness of siliceous sediments within a sequence dominated by volcaniclastic rocks. They are formed from lake deposits, based on the presence of five families of freshwater fish and other terrestrial taxa, and the fossil-bearing sediments have been dated to the Ypresian (Lower Eoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parastacidae
The Parastacidae are the family of freshwater crayfish found in the Southern Hemisphere. The family is a classic Gondwana-distributed taxon, with extant members in South America, Madagascar, Australia, New Zealand, and New Guinea, and extinct taxa also in Antarctica. Distribution Three genera are found in Chile, ''Virilastacus'', '' Samastacus'' and '' Parastacus'', the last of which also occurs disjunctly in southern Brazil and Uruguay. There are no crayfish native to continental Africa, but seven species on Madagascar, all of the genus '' Astacoides''. Australasia is particularly rich in crayfish. The small genus ''Paranephrops'' is endemic to New Zealand. The genera ''Astacopsis'' is endemic to Tasmania, while a further two are found on either side of the Bass Strait – '' Geocharax'' and ''Engaeus''. The greatest diversity, however, is found on the Australian mainland. Three genera are endemic and have restricted distributions (''Engaewa'', '' Gramastacus'' and ''Tenuib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
McAbee Fossil Beds
The McAbee Fossil Beds is a Heritage Site that protects an Eocene Epoch fossil locality east of Cache Creek, British Columbia, Canada, just north of and visible from Provincial Highway 97 / the Trans-Canada Highway ( Highway 1). The McAbee Fossil Beds, comprising , were officially designated a Provincial Heritage Site under British Columbia's Heritage Conservation Act on July 19, 2012. The site is part of an old lake bed which was deposited about 52 million years ago and is internationally recognised for the diversity of plant, insect, and fish fossils found there. Similar fossil beds in Eocene lake sediments, also known for their well preserved plant, insect and fish fossils, are found at Driftwood Canyon Provincial Park near Smithers in northern British Columbia, on the Horsefly River near Quesnel in central British Columbia, and at Republic in Washington, United States. The Princeton Chert fossil beds in southern British Columbia are also Eocene, but primarily preserve an aq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. 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. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna (biology)
Antennae ( antenna), sometimes referred to as "feelers", are paired appendages used for sensing in arthropods. Antennae are connected to the first one or two segments of the arthropod head. They vary widely in form but are always made of one or more jointed segments. While they are typically sensory organs, the exact nature of what they sense and how they sense it is not the same in all groups. Functions may variously include sensing touch, air motion, heat, vibration (sound), and especially smell or taste. Antennae are sometimes modified for other purposes, such as mating, brooding, swimming, and even anchoring the arthropod to a substrate. Larval arthropods have antennae that differ from those of the adult. Many crustaceans, for example, have free-swimming larvae that use their antennae for swimming. Antennae can also locate other group members if the insect lives in a group, like the ant. The common ancestor of all arthropods likely had one pair of uniramous (unbranched ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the Roman Republic it became the dominant language in the Italian region and subsequently throughout the Roman Empire. Even after the fall of Western Rome, Latin remained the common language of international communication, science, scholarship and academia in Europe until well into the 18th century, when other regional vernaculars (including its own descendants, the Romance languages) supplanted it in common academic and political usage, and it eventually became a dead language in the modern linguistic definition. Latin is a highly inflected language, with three distinct genders (masculine, feminine, and neuter), six or seven noun cases (nominative, accusative, genitive, dative, ablative, and vocative), five declensions, four verb conjuga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Crustacean Biology
The ''Journal of Crustacean Biology'' is a quarterly peer-reviewed scientific journal in the field of carcinology (crustacean research). It is published by The Crustacean Society and Oxford University Press (formerly by Brill Publishers and Allen Press), and since 2015 the editor-in-chief has been Peter Castro. According to the ''Journal Citation Reports'', its 2016 impact factor is 1.064. The journal has a mandatory publication fee of US$ 115 per printed page for non-members of the SocietyJournal of Crustacean BiologyInstructions for Authors/ref> and an optional open access Open access (OA) is a set of principles and a range of practices through which research outputs are distributed online, free of access charges or other barriers. With open access strictly defined (according to the 2001 definition), or libre op ... fee of $1830 minimum. References Further reading * * External links {{Wikispecies-inline, ISSN 0278-0372 Carcinology journals Publications establi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gut (anatomy)
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines. Food taken in through the mouth is digested to extract nutrients and absorb energy, and the waste expelled at the anus as feces. ''Gastrointestinal'' is an adjective meaning of or pertaining to the stomach and intestines. Most animals have a "through-gut" or complete digestive tract. Exceptions are more primitive ones: sponges have small pores ( ostia) throughout their body for digestion and a larger dorsal pore (osculum) for excretion, comb jellies have both a ventral mouth and dorsal anal pores, while cnidarians and acoels have a single pore for both digestion and excretion. The human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is div ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soft Tissue
Soft tissue is all the tissue in the body that is not hardened by the processes of ossification or calcification such as bones and teeth. Soft tissue connects, surrounds or supports internal organs and bones, and includes muscle, tendons, ligaments, fat, fibrous tissue, lymph and blood vessels, fasciae, and synovial membranes. with :q=a_E_E_ \qquad Q=b_E_E_ quadratic forms of Green-Lagrange strains E_ and a_, b_ and c material constants. W is the strain energy function per volume unit, which is the mechanical strain energy for a given temperature. Isotropic simplification The Fung-model, simplified with isotropic hypothesis (same mechanical properties in all directions). This written in respect of the principal stretches (\lambda_i): :W = \frac\left (\lambda_1^2 + \lambda_2^2 + \lambda_3^2 - 3) + b\left( e^ -1 \right) \right/math> , where a, b and c are constants. Simplification for small and big stretches For small strains, the exponential term is very small, thus neg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorapatite
Fluorapatite, often with the alternate spelling of fluoroapatite, is a phosphate mineral with the formula Ca5(PO4)3F (calcium fluorophosphate). Fluorapatite is a hard crystalline solid. Although samples can have various color (green, brown, blue, yellow, violet, or colorless), the pure mineral is colorless, as expected for a material lacking transition metals. Along with hydroxylapatite, it can be a component of tooth enamel, but for industrial use both minerals are mined in the form of phosphate rock, whose usual mineral composition is primarily fluorapatite but often with significant amounts of the other. Fluorapatite crystallizes in a hexagonal crystal system. It is often combined as a solid solution with hydroxylapatite (Ca5(PO4)3OH or Ca10(PO4)6(OH)2) in biological matrices. Chlorapatite (Ca5(PO4)3Cl) is another related structure. Industrially, the mineral is an important source of both phosphoric and hydrofluoric acids. Fluorapatite as a mineral is the most common p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
