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Euchelicerata
The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks, and mites, among many others), as well as a number of extinct lineages, such as the eurypterids (sea scorpions) and chasmataspidids. Chelicerata split from Mandibulata by the mid-Cambrian, as evidenced by stem-group chelicerates like Habeliida and '' Mollisonia'' present by this time. The surviving marine species include the four species of xiphosurans (horseshoe crabs), and possibly the 1,300 species of pycnogonids (sea spiders), if the latter are indeed chelicerates. On the other hand, there are over 77,000 well-identified species of air-breathing chelicerates, and there may be about 500,000 unidentified species. Like all arthropods, chelicerates have Segmentation (biology), segmented bodies with jointed limbs, all cove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pycnogonida
Sea spiders are marine arthropods of the class Pycnogonida, hence they are also called pycnogonids (; named after ''Pycnogonum'', the type genus; with the suffix '). The class includes the only now-living order Pantopoda ( ‘all feet’), alongside a few fossil species which could trace back to the early or mid Paleozoic. They are cosmopolitan, found in oceans around the world. The over 1,300 known species have leg spans ranging from to over . Most are toward the smaller end of this range in relatively shallow depths; however, they can grow to be quite large in Antarctic and deep waters. Despite their name and brief resemblance, "sea spiders" are not spiders, nor even arachnids. While some literature around the 2000s suggests they may be a sister group to all other living arthropods, their traditional classification as a member of chelicerates alongside horseshoe crabs and arachnids has regained wide support in subsequent studies. Morphology Many sea spiders are recognised ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Spider
Sea spiders are marine arthropods of the class (biology), class Pycnogonida, hence they are also called pycnogonids (; named after ''Pycnogonum'', the type genus; with the suffix '). The class includes the only now-living order (biology), order Pantopoda ( ‘all feet’), alongside a few fossil species which could trace back to the early or mid Paleozoic. They are cosmopolitan distribution, cosmopolitan, found in oceans around the world. The over 1,300 known species have leg spans ranging from to over . Most are toward the smaller end of this range in relatively shallow depths; however, they can grow to be quite large in Antarctic and deep-sea gigantism, deep waters. Despite their name and brief resemblance, "sea spiders" are not spiders, nor even arachnids. While some literature around the 2000s suggests they may be a sister group to all other living arthropods, their traditional classification as a member of chelicerates alongside Xiphosura, horseshoe crabs and arachnids has r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arachnida
Arachnids are arthropods in the class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegaroons. Adult arachnids have eight legs attached to the cephalothorax. In some species the frontmost pair of legs has converted to a sensory function, while in others, different appendages can grow large enough to take on the appearance of extra pairs of legs. Almost all extant arachnids are terrestrial, living mainly on land. However, some inhabit freshwater environments and, with the exception of the pelagic zone, marine environments as well. They comprise over 110,000 named species, of which 51,000 are species of spiders. The term is derived from the Greek word (''aráchnē'', 'spider'), from the myth of the hubristic human weaver Arachne, who was turned into a spider. Morphology Almost all adult arachnids have eight legs, unlike adult insects whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Offacolidae
Offacolidae is a family of basal euchelicerate arthropods from the Ordovician and Silurian of Europe, Morocco and North America. The family is united by several features, including paddle-like sixth post-cheliceral appendages, elongated chelicerae, and reduced first tergites, although these are apparently not unique to the clade, but instead euchelicerate or wider synapomorphies, therefore making the clade paraphyletic. Alongside this, ''Offacolus'' may be more basal than the rest of the clade, as its seventh exopod pair is unreduced and it has a bipartite telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ..., among other features. They share with most other euchelicerates a wide carapace, which has led to them being placed in the paraphyletic “ Synziphosurina” for a long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Offacolus
''Offacolus'' is an extinct genus of euchelicerate, a group of chelicerate arthropods. Its only species, ''O. kingi'', has been found in deposits from the Silurian period ( Homerian epoch) in the Wenlock Series Lagerstätte of Herefordshire, England. The genus is named after Offa, a king from the ancient kingdom of Mercia, and ''colus'', a person who dwelled among (this time referring to) the Offa's Dyke. The species name honors Robert Joseph King, a British mineralogist who found the fossils of ''Offacolus''. Similar to ''Dibasterium'', ''Offacolus'' possess limb-like exopods (outer limb branches) on appendage II to V, a character suggest to be plesiomorphic (observable in the putative stem-chelicerate taxon Habeliida) and lost within the prosomapod clade. Classification ''Offacolus'' was originally described as an arthropod with chelicerate affinities, with detailed redescription done by Sutton ''et al.'' 2002 further suggested it to be unambiguously a chelicerate arthro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Setapedites
''Setapedites'' is an extinct genus of Ordovician offacolid chelicerates from the Fezouata Formation of Morocco. The genus contains a single species, ''Setapedites abundantis''. Description ''Setapedites'' is roughly 6 mm long excluding the telson, with eleven body segments and a prosoma with six appendage pairs. The first appendage pairs are elongated chelicerae, with the other five being biramous appendages. The exopods of these appendages bear setae on their tips, hence the name ''Setapedites''. The opisthosoma is divided into a pre-abdomen and an abdomen. Each pre-abdomen segment has both a pair of appendages and on the tergites, leaf-shaped tergopleurae, although somite 14 and all of the abdominal somites lack appendages. The first pre-abdominal somite has a large, flap-like exopod. The abdominal somites have fused tergites and sternites forming ring-shaped structures, alongside two pairs of spines derived from the tergopleurae. Under the 11th tergite, a small, symmetri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibasterium
''Dibasterium'' is an extinct genus of euchelicerate, a group of chelicerate arthropods. Fossils of the single and type species, ''D. durgae'', have been discovered in the Coalbrookdale Formation of the Middle Silurian period (Homerian age) in Herefordshire, England (in the United Kingdom). The name of the genus is derived from the Latin words ''dibamos'' ("on two legs") and '' mysterium'' ("mystery"), meaning "mystery on two legs" and referring to its prosomal (of the head) limbs. The species name ''durgae'' comes from Durga, a Hindu goddess Hindu deities are the gods and goddesses in Hinduism. Deities in Hinduism are as diverse as its traditions, and a Hindu can choose to be polytheistic, pantheistic, monotheistic, monistic, even agnostic, atheistic, or humanist. Julius J. Lip ... with many arms. References Euchelicerata Fossils of England Silurian arthropods of Europe Silurian animals Wenlock first appearances Homerian extinctions Fossil taxa described in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurypterid
Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 Myr, million years ago. The group is likely to have appeared first either during the Early Ordovician or Late Cambrian period. With approximately 250 species, the Eurypterida is the most diverse Paleozoic Chelicerata, chelicerate order. Following their appearance during the Ordovician, eurypterids became major components of marine faunas during the Silurian, from which the majority of eurypterid species have been described. The Silurian genus ''Eurypterus'' accounts for more than 90% of all known eurypterid specimens. Though the group continued to diversify during the subsequent Devonian period, the eurypterids were heavily affected by the Late Devonian extinction event. They declined in numbers and diversity until becoming extinct during the Permi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollisoniida
Mollisoniida is an extinct order of chelicerates, living from the mid-Cambrian to Early Ordovician. The clade is united by the presence of various characteristics. These include an elongated dorsal exoskeleton, seven articulating tergites and similarly sized cephalic and pygidial shields, in addition to only having three pairs of walking legs and the rest of the limbs being used as gills (which likely places them nearest to Euchelicerata, due to sharing similar arrangements of limbs). The clade is relatively diverse, containing three (possibly four) genera. '' Mollisonia'' and '' Thelxiope'' are both known from four species extending from Cambrian to Ordovician, with ''Thelxiope'' being very spiny and often with a shortened body. ''Mollisonia'', on the other hand, barely has any spines at all, and (with the exception of ''Mollisonia plenovenatrix'' and ''Mollisonia sinica'', which are similarly shaped to ''Thelxiope'') has a relatively elongated body. '' Corcorania'' is purely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weinbergina
''Weinbergina'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Fossils of the single and type species, ''W. opitzi'', have been discovered in deposits of the Devonian period in the Hunsrück Slate, Germany. Morphology ''Weinbergina'' is a relatively large synziphosurine, ranging about 7 cm to 10 cm in full body length. The prosoma is covered by a semicircular carapace with blunt genal cornua (posterolateral corners). There is possible evidence of lateral eyes located just below the ophthalmic ridges. The opisthosoma is externally 10-segmented, expressed by tergites that possess blunt tergopleurae (lateral extension) and axial nodes. However, the opisthosoma is most likely 11-segmented in origin, with the first segment being highly reduced (a synapomorphy of euchelicerates) and possibly covered by the preceding carapace. The last 3 segments form a narrow postabdomen and lacking lateral nodes. Compared to other synziphosurines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bunaia
''Bunaia'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Bunaia'' was tentatively placed as part of the clade Planaterga, however a 2024 study found it to be within Offacolidae instead. The genus contains at least one species: ''Bunaia woodwardi'' from the Silurian period in Svalbard, Norway and the Bertie Group of Ontario Description Initially, the species was known only from poorly preserved specimens composed of semicircular carapace, fragments of opisthosoma and disarticulated telson. The aforementioned 2024 study described additional specimens, which revealed "a pair of elongated chelicerae in the prosoma, followed posteriorly by five pairs of biramous appendages, a first pre-abdomen somite bearing a pair of paddle-like uniramous appendages ( exopods) and a ventral pretelsonic process." Taxonomy The placement of ''"Bunaia" heintzi'' (known only by a single carapace from the Silurian period in the United States The Unite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Cambrian
Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (other) * Middle Brook (other) * Middle Creek (other) * Middle Island (other) * Middle Lake (other) * Middle Mountain, California * Middle Peninsula, Chesapeake Bay, Virginia * Middle Range, a former name of the Xueshan Range on Taiwan Island * Middle River (other) * Middle Rocks, two rocks at the eastern opening of the Straits of Singapore * Middle Sound, a bay in North Carolina * Middle Township (other) * Middle East Music *Middle (song), "Middle" (song), 2015 *The Middle (Jimmy Eat World song), "The Middle" (Jimmy Eat World song), 2001 *The Middle (Zedd, Maren Morris and Grey song), "The Middle" (Zedd, Maren Morris and Grey song), 2018 *"Middle", a song by Rocket from the Crypt from their 1995 album ''Scream, Dracula, Scream!'' *"The Middle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
