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Palaeothele
''Palaeothele'' is an extinct genus of mesothele spiders, with only one known species ''Palaeothele montceauensis''. Two fossils were found at Montceau-les-Mines, France, in ironstone concretion deposits of Late Carboniferous ( Stephanian) age, about . Taxonomy The genus was first named as ''Eothele'' by Paul A. Selden in 1996. However, this name had already been used for a Cambrian brachiopod, so in 2000, Selden proposed the replacement name ''Palaeothele''. ''Palaeothele'' is derived from the Greek , "ancient", and , "nipple" – a common ending for spider names, referring to their spinnerets. The species name ''montceauensis'' refers to the location where the fossils were found. Phylogeny In 1996, Selden suggested the relationships shown in the cladogram below. (At the time, ''Attercopus'' was thought to be a spider; it is now considered to belong to a related but separate group, the Uraraneida.) ''Palaeothele'' is shown as sister to the modern genus ''Heptathela'' since th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesothelae
The Mesothelae are a suborder of spiders (order Araneae) that includes a single extant family, Liphistiidae, and a number of extinct families. This suborder is thought to form the sister group to all other living spiders, and to retain ancestral characters, such as a segmented abdomen with spinnerets in the middle and two pairs of book lungs. Members of Liphistiidae are medium to large spiders with eight eyes grouped on a tubercle. They are found only in China, Japan, and southeast Asia. The oldest known Mesothelae spiders are known from the Carboniferous, over 300 million years ago. The Heptathelidae were once considered their own family; today they are considered a subfamily of the Liphistiidae. Description Members of Mesothelae have paraxial chelicerae, two pairs of coxal glands on the legs, eight eyes grouped on a nodule, two pairs of book lungs, and no endites on the base of the pedipalp. Most have at least seven or eight spinnerets near the middle of the abdomen. Lateral ... [...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] |
Opisthothelae
The Opisthothelae are spiders within the order Araneae, consisting of the Mygalomorphae and the Araneomorphae, but excluding the Mesothelae. The Opisthothelae are sometimes presented as an unranked clade and sometimes as a suborder of the Araneae. In the latter case, the Mygalomorphae and Araneomorphae are treated as infraorders. The fairly recent creation of this taxon has been justified by the requirement to distinguish these spiders from the Mesothelae, which display many more primitive characteristics. Those that distinguish between the Mesothelae and Opisthothelae are: * The tergite plates on the abdomen of Mesothelae but absent in Opisthothelae * The almost total absence of ganglia in the abdomen of Opisthothelae * The almost median position of the spinnerets in the Mesothelae compared with the hindmost position of those of the Opistothelae Among the Opisthothelae, the fangs of the Mygalomorphae point straight down in front of the mouth aperture and only allow the sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liphistius
''Liphistius'' is a genus of basal trapdoor spiders in the family Liphistiidae. They are found in Japan, China, and Southeast Asia. Etymology ''Liphistius'' is from the Greek ''leipo'' (lacking) and ''stios'' (equality). Biology Female body lengths range from 9 to 29 mm; males are slightly smaller. They live in burrows in earthen banks, on some cave walls, and probably in forests. The burrow is sealed with a thin, circular, woven door, which is disguised with soil and moss. While they spend the day deep inside their burrows, at night they wait just below the door for insects, woodlice, and similar invertebrates that stumble over one of the seven silken threads that radiate from the entrance. With a reluctance to leave their burrows, they push up the door and reach for their prey. Murphy, Frances & Murphy, John (2000): An Introduction to the Spiders of South East Asia. ''Malaysian Nature Society'', Kuala Lumpur. Species , the World Spider Catalog accepts the following sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Book Lungs
A book lung is a type of respiration organ used for atmospheric gas exchange that is present in many arachnids, such as scorpions and spiders. Each of these organs is located inside an open ventral abdominal, air-filled cavity (atrium) and connects with the surroundings through a small opening for the purpose of respiration. Structure and function Book lungs are not related to the lungs of modern land-dwelling vertebrates. Their name describes their structure and purpose. Stacks of alternating air pockets and tissue filled with hemolymph give them an appearance similar to a "folded" book. Their number varies from just one pair in most spiders to four pairs in scorpions. The unfolded "pages" (plates) of the book lung are filled with hemolymph. The folds maximize the surface exposed to air, and thereby maximize the amount of gas exchanged with the environment. In most species, no motion of the plates is needed to facilitate this kind of respiration. Occasionally absent Sometimes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heptathela
''Heptathela'' is a genus of spiders that includes the Kimura spider (''Heptathela kimurai''). They are trapdoor spiders of the family Liphistiidae and are found in Japan, including Okinawa Island, Okinawa and the Ryukyu Islands. Spiders of this genus lack venom glands. Full text at (60 MB) Females are up to 25 mm long, males slightly smaller. Burrows have an oval shaped door which is hinged across the long diameter. Name The genus name is derived from Ancient Greek ''hepta'' "seven", referring to the number of Spinneret (spider), spinneret glands. Species , the World Spider Catalog accepted the following species: *''Heptathela aha'' Xu, Ono, Kuntner, Liu & Li, 2019 – Ryukyu Is. *''Heptathela amamiensis'' Haupt, 1983 – Ryukyu Is. *''Heptathela crypta'' Xu, Ono, Kuntner, Liu & Li, 2019 – Ryukyu Is. *''Heptathela gayozan'' Xu, Ono, Kuntner, Liu & Li, 2019 – Ryukyu Is. *''Heptathela helios'' Tanikawa & Miyashita, 2014 (synonym ''H. yaginumai'' Ono, 1998) – Jap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uraraneida
Uraraneida is an extinct order of arachnids, known from fossils of Middle Devonian, Permian and possibly Cretaceous age. Two genera of fossils have been definitively placed in this order: ''Attercopus'' from the Devonian of United States and ''Permarachne'' from the Permian of Russia. In 2018, a third genus ''Chimerarachne'', from the Cretaceous of Myanmar was proposed to belong to this group, but this placement is disputed. When the first fossils were found, they were identified as spiders, but now constitute the Uraraneida, a separate but closely related group. Characteristics The first fossil now placed in the order was found in Gilboa, New York. In 1987, it was initially tentatively placed in the extinct order Trigonotarbida and named ''Gelasinotarbus''? ''fimbriunguis''. Later, partly on the basis of a supposed spinneret (spider), spinneret, it was identified as a spider and named ''Attercopus fimbriunguis''. Further specimens of this species were found, and when examined in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Attercopus
''Attercopus'' is an extinct genus of arachnids, containing one species ''Attercopus fimbriunguis'', known from flattened cuticle fossils from the Panther Mountain Formation in Upstate New York. It is placed in the extinct order Uraraneida, spider-like animals able to produce silk, but which lacked true spinnerets and retained a segmented abdomen bearing a flagellum-like tail resembling that of a whip scorpion. They are thought to be close to the origins of spiders. Its name is taken from the English dialect word ''attercop'' ("spider"), which came from '' ang, attorcoppa'' ("poison-head"), from '' ang, ator'' ("poison"), itself drawn from the Proto-Germanic ''*aitra-'' ("poisonous ulcer") and ''kopp-'' ("head"). An important Early Devonian (about ) fossil example from Gilboa, New York, was originally described as a member of the extinct order Trigonotarbida and named ''Gelasinotarbus? fimbriunguis''. It was later assigned to a new genus ''Attercopus'' and reinterpreted as t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinneret (spider)
A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and are typically segmented. While most spiders have six spinnerets, some have two, four, or eight. They can move both independently and in concert. Most spinnerets are not simple structures with a single orifice producing a single thread, but complex structures of many microscopic spigots, each producing one filament. This produces the necessary orientation of the protein molecules, without which the silk would be weak and useless. Spigots can be singular or found in groups, which also permits spiders to combine multiple filaments in different ways to produce many kinds of silk for various purposes. Spinneret morphology can help arachnologists identify the taxon of a specimen and the specific morphology of a spigot can determine its use as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic period (), and the Classical period (). Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Epic and Classical periods of the language. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regarded as a separate historical stage, although its earliest form closely resembles Attic Greek and its latest form approaches Medieval Greek. There were several regional dialects of Ancient Greek, of which Attic Greek developed into Koine. Dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopod
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major categories are traditionally recognized, articulate and inarticulate brachiopods. The word "articulate" is used to describe the tooth-and-groove structures of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic skeletal feature, by which the two main groups can be readily distinguished as fossils. Articulate brachiopods have toothed hinges and simple, vertically-oriented opening and closing muscles. Conversely, inarticulate brachiopods have weak, untoothed hinges and a more complex system of vertical and oblique (diagonal) muscles used to keep the two valves aligned. In many brachiopods, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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