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Planaterga
Planaterga is a clade of prosomapod euchelicerates including several synziphosurid genera (mainly bunodids and pseudoniscids) and the group Dekatriata (which in turn includes arachnids, chasmataspidids and eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is ...s). Planaterga is defined by the opisthosoma with tergites broadest at third or fourth and lacking enlarged axial nodes, carapace (prosomal dorsal shield) with reduced genal spines, as well as somite VII (first opisthosomal segment) with reduced appendages and microtergite. References Middle Ordovician first appearances {{Chelicerata-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pasternakevia
''Pasternakevia'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Pasternakevia'' was regarded as part of the clade Planaterga. Fossils of the single and type species, ''P. podolica'', have been discovered in deposits of the Silurian period in Podolia, Ukraine. The prosoma of ''Pasternakevia'' covered by a smooth, semicircular carapace with rounded genal cornua (posterolateral corner of carapace). Within the 10-segmented opisthosoma, tergite of the first segment is reduced and usually hidden under the preceding carapace, while the second one is significantly arched and well-developed. All but the first tergite possess well-developed pleurae (lateral extension). A complete telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on accou ... is yet to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bembicosoma
''Bembicosoma'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Bembicosoma'' was regarded as part of the clade Planaterga. Fossils of the single and type species, ''B. pomphicus'', have been discovered in deposits of the Silurian period in the Pentland Hills, Scotland (in the United Kingdom). ''Bembicosoma'' had been tentatively assigned as an eurypterid (sea scorpion) before its synziphosurine affinities revealed. The prosoma of ''Bembicosoma'' covered by a short, semicircular carapace without evidence of ophthalmic ridges. Within the 10-segmented opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects ..., the first segment is nearly as wide as the carapace but reduced in length while the second segment is the largest. The dorsal surfac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bunodidae
Bunodidae is an extinct family of synziphosurine chelicerates that lived in the Silurian. Bunodidae is classified inside the clade Planaterga alongside Pseudoniscidae and Dekatriata ( chasmataspidids, eurypterids and arachnids). Bunodidae is composed by two genera, ''Bunodes'' (the type genus) and ''Limuloides ''Limuloides'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Limuloides'' was regarded as part of the clade Planaterga. Fossils of the genus have been discovered in deposits of the Silurian period in th ...''. References Synziphosurina Planaterga Silurian first appearances Silurian arthropods Silurian extinctions Prehistoric arthropod families {{Chelicerata-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudoniscidae
Pseudoniscidae is an extinct family of synziphosurine chelicerates that lived in the Silurian. Pseudoniscidae is classified inside the clade Planaterga, alongside Bunodidae and Dekatriata ( chasmataspidids, eurypterids and arachnids). Pseudoniscidae is composed by two genera, ''Cyamocephalus'' and ''Pseudoniscus ''Pseudoniscus'' is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. ''Pseudoniscus'' was regarded as part of the clade Planaterga. Fossils of the genus have been discovered in Deposition (geology), deposits of th ...'' (the type genus). References Synziphosurina Planaterga Silurian first appearances Silurian arthropods Silurian extinctions Prehistoric arthropod families {{Chelicerata-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosomapoda
Prosomapoda is a clade of euchelicerates including the groups Xiphosura (horseshoe crabs) and Planaterga (a group comprising bunodids, pseudoniscids, chasmataspidids, eurypterids and arachnids), as well as several basal synziphosurid genera. The clade is defined by the lack of exopods (outer branches) of prosomal appendage II-V in the adult instar, where in contrast the exopods of appendage II-V are well-developed in the non-prosomapod euchelicerates ''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, Eng ...'' and '' Dibasterium''. References Middle Ordovician first appearances {{Chelicerata-stub ... [...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. The genus contains at least one species: ''Bunaia woodwardi'' from the Silurian period in Svalbard, Norway. Only a few morphological information of ''B''. ''woodwardi'' had been confirmed, as the species known only from poorly preserved specimens compose of semicircular carapace, fragments of opisthosoma and disarticulated telson. The placement of ''"Bunaia" heintzi'' (known only by a single carapace from the Silurian period in the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...) within this genus had been questioned and required further investigation. References Synziphosurina Silurian first ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelicerate
The subphylum Chelicerata (from New Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. It contains 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. The Chelicerata originated as marine animals in the Middle Cambrian period; the first confirmed chelicerate fossils, belonging to '' Sanctacaris'', date from 508 million years ago. 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 segmented bodies with jointed limb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurypterid
Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 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 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 Permian–Triassic extinction event (or sometim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dekatriata
Dekatriata is a clade of planatergan chelicerates including the groups Arachnida, Chasmataspidida, Eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is ...a and additionally two stem-genera '' Winneshiekia'' and '' Houia''. Dekatriata is defined by an opisthosoma with 13 segments as groundplan (the number proposed to be secondarily reduced in most arachnid orders) and fused, plate-like appendages on the first opisthosomal segment (somite VII). References Middle Ordovician first appearances {{Chelicerata-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
