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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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alalcomenaeus
''Alalcomenaeus'' is one of the most widespread and longest-surviving arthropod genera of the Early and Middle Cambrian. Known from over 300 specimens in the Burgess Shale and the Chengjiang biota. it is a member of the group Megacheira. Morphology ''Alalcomenaeus'' had three median eyes; two stalked, more lateral eyes; a triflagellate great appendage; and two more head appendages posterior to that. Like its body appendages, these were biramous—their inner branch was spiny, segmented, flexible and leg-like, while the outer portion had a large surface area and resembled a flap. ''Alalcomenaeus'' reached about 6 cm in length, although many smaller specimens are known. Its head was covered with a shield, and its eleven body segments were also covered with an exoskeleton. Its body terminated with a paddle-like telson ("tail") which probably helped to propel the organism; this ended with long flat spikes in the plane of the tail fin. Ecology The organism probably swam, wafti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arthropod cuticle, cuticle made of chitin, often Mineralization (biology), 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 exoskeleton, 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 Organ (anatomy), organs; it has an open circulatory system. Like their exteriors, the internal or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oestokerkus
''Oestokerkus'' is an extinct genus of Cambrian megacheiran arthropod known from the Emu Bay Shale of Kangaroo Island, Australia. It belongs to the family Leanchoiliidae. It had a large head shield that was more than a third of the trunk's length, as well as a large pair of eyes. The great appendages have long flagellae projecting from them. The head shield probably had two pairs of cephalic appendages. The trunk has 11 segments. The exopods of the biramous limbs are fringed with long setae. The body ended with a 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 ..., which was probably dorsally flattened. References {{Taxonbar, from1=Q21369030, from2=Q15056321 Megacheira Cambrian arthropods Cambrian Series 2 first appearances Fossil taxa described in 2011 Prehistor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bundenbachiellus
''Bundenbachiellus'' is an extinct genus of arthropod described from the Lower Devonian Hunsrück Slate of Germany. This genus is known from only one species, ''B. giganteus''. Alongside its possible relative ''Enalikter'' from Silurian, it is possible that genus is late-living example of Megacheira, "great-appendage arthropod". History ''Bundenbachiellus giganteus'' was described in 1929 with the name of ''Megadactylus giganteus'', with incomplete specimen BSPG 1929 II 34, however genus name ''Megadactylus'' was already used for synonym of dinosaur '' Anchisaurus'', its genus name was changed into ''Bundenbachiellus'' in 1930.BROILI, F. 1930. Ein neuer Fund von ?"Megadactylus". - Sitzungsberichte der Bayerischen Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Abteilung 1930: 215-222. Second species, ''B. minor'' was also described, however that species is later considered as misinterpretation of a trilobite. Due to holotype specimen was incomplete, preserve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enalikter
''Enalikter'' ("scourger of the sea") is an extinct arthropod described from the middle Silurian Herefordshire Lagerstätte at the England–Wales border in UK. This genus is known from only one species, ''E. aphson''. ''Enalikter'' is described as late-living example of Megacheira, "great-appendage arthropod". It was once considered as an annelid by other researchers, however subsequent studies denied this. Its interpretation as megacheiran arthropod is questioned in later study. Morphology ''Enalikter'' is small arthropod with length just around long. Head shield is subrectangular and lacked eyes. Median, unpaired antenna and three pairs of appendages can be seen on head, and a first appendage had three tapering flagella. Twelve trunk segments lack tergites, and is flexible to bend at least 90 degrees. Trunk appendages are biramous. Egg-like shaped telson had two pairs of blade-like processes. Classification ''Enalikter'' is probably related to ''Bundenbachiellus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kootenichela
''Kootenichela deppi'' is an extinct arthropod described from the Middle Cambrian of the Kootenay National Park, Canada. It is originally considered to be a member of "great appendage arthropods", although subsequent studies questioned its affinity. ''Kootenichela'' appears to be the sister taxon of '' Worthenella'', from cladistic analysis. The species name ''deppi'' comes from the actor Johnny Depp, after his role as Edward Scissorhands in the film of the same name. David Legg, the discoverer of ''Kootenichela'', said: ''Kootenichela'' appears to be a primitive arthropod. It has an elongated body composed of at least 29 segments of similar shape and appearance. On the head, there are large eyes supported by stalks and an appendage resembling an antenna. The appendages bound to the trunk are poorly sclerotised. It was approximately long. Most prominent are the claw-like, spinose cephalic appendages, which seem to suggest affinities with Megacheira, the "great appendage" arth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
