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Euarthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an external skeleton. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species. The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior organs; it has an open circulatory system. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. Their nervous system is "ladder-lik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiodonta
Radiodonta is an extinct Order (biology), order of stem-group arthropods that was successful worldwide during the Cambrian period. They may be referred to as radiodonts, radiodontans, radiodontids, anomalocarids, or anomalocaridids, although the last two originally refer to the family Anomalocarididae, which previously included all species of this order but is now restricted to only a few species. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and used for a variety of functions. Radiodonts included the earliest large predators known, but they also included sediment sifters and filter feeders. Some of the most famous species of radiodonts are the Cambrian taxa ''Anomalocaris, Anomalocaris canadensis'', ''Hurdia, Hurdia victoria'', ''Peytoia nathorsti'', ''Titanokorys gainesii, Titanokorys gainessii, Cambroraster, Cambroraster falcatus'' and ''Amplectobelua, Amplectobelua symbrachiata'', the Ordovician ''Aegirocassis, Aegiroca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinocaridida
DinocarididaGreek, "Terrible crabs" – sometimes informally spelt Dinocarida, but the second 'id' is linguistically correct – see is a proposed fossil taxon of basal arthropods that flourished in the Cambrian period with occasional OrdovicianVan Roy, P.; Briggs, D. E. G. (2011). "A giant Ordovician anomalocaridid". Nature 473 (7348): 510–513. doi:10.1038/nature09920. edit and Devonian records. Characterized by a pair of frontal appendages and series of body flaps, the name of Dinocaridids comes from Greek language, Greek, "deinos" and "caris" ("terrible crab"), referring to the suggested role of some of these members as the largest Marine life, marine Predation, predators of their time. Dinocaridids are occasionally referred to as the 'AOPK group' by some literatures, as the group compose of Radiodonta (''Anomalocaris'' and relatives), Opabiniidae (''Opabinia'' and relatives), ''Pambdelurion'' and ''Kerygmachela.'' It is most likely paraphyletic, with ''Kerygmachela'' and ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nektaspida
Nektaspida (also called Naraoiida, Nektaspia and Nectaspida) is an extinct order of non- mineralised artiopodan arthropods. They are known from the mid-Cambrian to the upper Silurian. Originally classified as trilobites, which they superficially resemble, they are now placed as close relatives as members of the Trilobitomorpha within Artiopoda. The order is divided into three major families; Emucarididae, Liwiidae, and Naraoiidae. Naming history and taxonomic placement The order was originally proposed by Raymond in 1920 as Nektaspia. Størmer corrected it to Nectaspida for the 1959 ''Treatise on Invertebrate Paleontology'' to conform with the names of the other trilobite orders. Whittington described it in 1985 with the spelling Nektaspida; the revised 1997 Treatise by Raymond and Fortey uses this spelling, as do other modern works. Whittington (1985) placed the order in the Trilobita. Cotton & Braddy (2000) place it in a new "Trilobite clade" containing the Trilobita, recogni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobopodia
The lobopodians, members of the informal group Lobopodia (from the Greek language, Greek, meaning "blunt feet"), or the formally erected phylum Lobopoda Cavalier-Smith (1998), are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as well. While the definition of lobopodians may differ between literatures, it usually refers to a group of soft-bodied, worm-like fossil panarthropods such as ''Aysheaia'' and ''Hallucigenia''. The oldest near-complete fossil lobopodians date to the Lower Cambrian; some are also known from Ordovician, Silurian and Carboniferous Lagerstätten. Some bear toughened claws, plates or spines, which are commonly preserved as small carbonaceous fossil, carbonaceous or Small Shelly Fossils, mineralized microfossils in Cambrian strata. The grouping is considered to be paraphyletic, as the three living panarthropod groups (Arthropoda, Tardigrada and Onychophora) are thought to have evolved from lobopodian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erratus
''Erratus'' is an extinct genus of marine arthropod from the Cambrian of China. Its type and only species is ''Erratus sperare''. ''Erratus'' is likely one of the most basal known arthropods, and its discovery has helped scientists understand the early evolution of arthropod trunk appendages. Some of the stem-arthropods like radiodonts did not have legs, instead they had flap like appendages that helped them swim. ''Erratus'' on the other hand had not only flaps but also a set of primitive legs. It also supported the theory that the gills of aquatic arthropods probably evolved into the wings and lungs of terrestrial arthropods later in the Paleozoic. Fossils of ''Erratus'' have been found in the Chengjiang Lagerstätte of China, dating to around 520 million years ago. ''Erratus'' was a small, nektonic organism with a bivalved carapace that probably ate by deposit feeding or filter feeding. History of study The holotype consists of specimens XDBZ101 and XDBZ102. The paratype spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fuxianhuiida
Fuxianhuiida is an extinct clade of arthropods from the Cambrian of China. All currently known species are from Cambrian Series 2 aged deposits in Yunnan Province, including the Chengjiang biota. They are generally considered to be close to the base of Euarthropoda, but have also been considered to be early mandibulates. Many specimens are known with exceptional soft tissue preservation, including preserved guts and neural tissue, which given their basal phylogenetic position makes them important in understanding the evolution of arthropoda as a whole. They reach a size of up to 15 cm, and are interpreted as benthic predators and scavengers. The fuxianhuiid exoskeleton is unmineralised, and the number of tergites ranges from 15 to over 40. The cephalon is covered by a head shield and contains stalked eyes connected by the anterior sclerite, antennae, a butterfly shaped hyposome and a posterior facing mouth. Fuxianhuiids possess specialized post-antennal appendages with se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opabiniidae
Opabiniidae is an extinct family of bizarre marine stem-arthropods. Its type and best-known genus is ''Opabinia''. It also contains ''Utaurora''. Opabiniids closely resemble radiodonts, but their frontal appendages were basally fused into a proboscis. Opabiniids also distinguishable from radiodonts by setal blades covering at least part of the body flaps and serrated caudal rami. History of study Opabiniidae was named by Charles Doolittle Walcott in 1912, alongside its type species ''Opabinia''. Walcott interpreted Opabiniidae as a family of anostracan crustaceans, most closely related to Thamnocephalidae. ''Opabinia'' was restudied in the 1970s, and reinterpreted as a stranger animal. Stephen Jay Gould referred to ''Opabinia'' as a "weird wonder", and an illustration of ''Opabinia'' prompted laughter when it was first revealed at a paleontological conference. In 2022, a second opabiniid, ''Utaurora'', was identified. ''Myoscolex'' from Emu Bay Shale is sometimes suggested to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kiisortoqia
''Kiisortoqia soperi'' is an extinct species of arthropod from the Early Cambrian Sirius Passet Lagerstätte in Greenland. While it had a superficially trilobite-like bodyform, it also possessed large frontal appendages similar to those of radiodonts. Description The body of ''K. soperi'' consisted of a simple head shield, 16 trunk segments (tergites) and a tail plate. In outward appearance the body is almost elliptical, about twice as long as wide, with the widest point in the front third of the body at the 3rd to 5th tergite. The head plate was simple, convex in shape, wider than long, and represented about 20% of the total body length. The tergites were short, about five times as wide as long, and the rear edge of each tergite overlapped the following by about a fifth of its length. The tergites 1–5 all had about the same width, the following tergites becoming narrower towards the posterior end of the animal. In the middle of the tergites an axis can be clearly seen, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megacheira
Megacheira ("great hands") is an extinct class of predatory arthropods that possessed a pair of great appendages, hence the class name as well as the common name "great appendage arthropods". Their taxonomic position is controversial, with studies either considering them stem-group euarthropods, or stem-group chelicerates. Most of them were found in marine environments throughout the world from the lower to middle Cambrian. Megacheirans were important components of several faunas, including the Burgess, Wheeler and Maotianshan Shales Lagerstatten. Homology of great appendages The homology between megacheiran great appendages and cephalic appendages of other arthropods had been discussed for decades. There is controversy over whether they are homologous to both dinocaridid (radiodonts and gilled lobopodians) frontal appendages, the frontalmost appendages of ''Isoxys'' and chelicerates' chelicerae. Based on neuroanatomical evidences, many studies support their homology to ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kylinxia
''Kylinxia'' is a genus of extinct arthropod described in 2020. It was described from six specimens discovered in Yu'anshan Formation (Maotianshan Shales) in southern China. The specimens are assigned to one species ''Kylinxia zhangi.'' Dated to 518 million years, the fossils falls under the Cambrian period. Announcing the discovery on 4 November 2020 at a press conference, Zeng Han of the Nanjing Institute of Geology and Paleontology, said that the animal "bridges the evolutionary gap from ''Anomalocaris'' to true arthropods and forms a key ‘ missing link’ in the origin of arthropods," which was "predicted by Darwin’s evolutionary theory." The same day the formal description was published in ''Nature''. Discovery ''Kylinxia zhangi'' was discovered among the Maotianshan Shales from Yu'anshan Formation at Yunnan in southern China in 2019. Zeng Han, Zhao Fangchen, and Huang Diying of the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, made the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fengzhengia
''Fengzhengia'' is an extinct genus of arthropod known from a single species, ''Fengzhengia mamingae'' from the Cambrian aged Chengjiang Biota of Yunnan, China. It is thought to be a basal arthropod, as one of the most basal members of Deuteropoda. Like other basal deuteropods such as ''Kylinxia'', ''Fengzhengia'' has an upward curling pair of "frontal appendages", contrasting with the downward curving pair of frontal appendages possessed by radiodonts. The head has a pair of stalked eyes. The trunk had 15 tergites the first nine of which had upward facing spines, with the trunk terminating with a tail fan. The trunk seemingly had pairs of biramous limbs, with paddle-shaped exopod The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, plur ...s. It is thought to have been nektobenthic (swimmin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anomalocaris
''Anomalocaris'' ("unlike other shrimp", or "abnormal shrimp") is an extinct genus of Radiodonta, radiodont, an Order (biology), order of early-diverging stem-group arthropods. The first fossils of ''Anomalocaris'' were discovered in the ''Ogygopsis'' Shale of the Stephen Formation in British Columbia, Canada by Joseph Frederick Whiteaves, with more examples found by Charles Doolittle Walcott in the Burgess Shale unit of the Stephen Formation. Other closely related fossils have been found in the older Emu Bay Shale of Australia, as well as possibly elsewhere. Originally several fossilized parts discovered separately (the mouth, frontal appendages and trunk) were thought to be three separate creatures, a misapprehension corrected by Harry B. Whittington and Derek Briggs in a 1985 journal article. With a body length close to 40 centimetres, ''A. canadensis'' is thought to be one of the earliest examples of an apex predator, though others have been found in older Cambrian lagerstätte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
