Anomalocarid 106060 219576430 2008-06-15T22:28:49Z Elatrin 6119853 {{Taxobox | name = Anomalocarid | status = Fossil | image = Anomalocarid.jpg | image_caption = Artist's reconstruction of an anomalocarid hunting a [[trilobite]]. | superregnum = [[Eukarya]] | regnum = [[Animal]]ia | subregnum = [[Eumetazoa]] | superphylum = [[Protostomia]] | phylum = †[[Dinocarida]] | ordo = [[Radiodonta]] not divided | classis = '''Anomalocarida''' | familia = [[Anomalocaridae]] | subdivision_ranks = [[Genus]] | subdivision = *[[Anomalocaris]] *[[Laggania]] *[[Cucumericrus]] *[[Amplectobelua]] *[[Parapeytoia]]? }} '''Anomalocarids''' ("Strange [[shrimp]]") are a group of very early marine animals known from fossils found in [[Cambrian]] deposits in [[China]], [[USA]], [[Canada]], [[Poland]] and [[Australia]]. Anomalocarids are the largest Cambrian animals known (some Chinese forms grew up to 2&nbsp;[[metre|m]], and most of them were probably active [[carnivore]]s although recent thought posits one genus, ''Laggania'', as a [[plankton]]-eating animal). ==Characteristics== Anomalocarids were flat free-swimming segmented animals, which in front of their mouths had two appendages that look like the bodies of [[shrimp]]s. The mouth is a peculiar circular structure like a [[pineapple]] slice, but with a ring of hard sharp teeth in the central orifice. The mouth was more rectangular than round, and the teeth did not meet in the middle. This would still let it crack open shells of small [[arthropod]]s and other like animals, such as [[trilobite]]s. Indeed, many trilobites have been found with bite marks on them. Anomalocarids also had large eyes and a body half-flanked with a series of swimming lobes. ''[[Parapeytoia yunnanensis]]'', one species of anomalocarid (many scientists debate whether or not Parapeytoia was a true anomalocarid, or rather more closely related to Yohoia or Haikoucaris), may even have had legs[http://www.trilobites.info/species2.html]. Compared with many of the other sea-dwelling creatures of its time, anomalocarids were extremely agile. The flaps along its body could probably be moved in a wave-like formation, allowing it to move at great speeds or to 'hover'. This motion could be compared to present-day [[Batoidea]] (rays), or perhaps [[cuttlefish]]. The shell of the anomalocarids was more flexible than those of its prey, allowing it easier movement. After death this large organism tended to disintegrate and fall apart into separate chunks; the same happened with its [[ecdysis|moulted skins]]. Completely intact fossil remains of it are very rare. When the fossils were originally described, the jointed arms in front of the mouth were classified as separate arthropods (a large mystery before the fossils were fully reassembled was why these fossils, mistaken as "[[shrimp]]s", were always found without "heads"), the mouth was thought to have been a fossilized [[jellyfish]] called "''Peytoia''", and the body, thought to be a sponge named "''Laggania''" was not associated with either. Since the pieces were reassembled in the 1980s, a number of [[genus|genera]] and [[species]] have been described that differ in the details of the grasping appendages, as to whether a tail is present, mouth location, and other features. The name ''Anomalocaris'' (meaning "strange shrimp") originally referred to the detached arms (which were the first part to be named), and was later used for the whole animal because of the [[Nomenclature Codes|biological name priority rules]]. Curiously enough, when fully assembled, these animals do strongly resemble (in outside appearance) a gigantic [[brine shrimp]] with a pair of finger-like appendages near its mouth. The anomalocarids thrived in the Early and Mid [[Cambrian]] and then apparently died out. It is possible that large [[Cephalopods]] replaced them as the dominant swimming predator at the end of the Cambrian. == Classification == Three genera of anomalocarids are known: ''[[Anomalocaris]]'', ''[[Laggania]]'', and ''[[Amplectobelua]]''. A variety of other related animals including ''[[Parapeytoia]]'', ''[[Pambdelurion]]'' and ''[[Kerygmachela]]'' are sometimes classified as anomalocarids, but probably belong to different clades. Compared with ''Anomalocaris'' species, ''Laggania species'' lacked tail structures and had a considerably larger head with the eyes placed behind instead of in front of the mouth, which would have been disadvantagous for active hunting. Because of these characteristics, some scientists have described ''Laggania'' as a cruising, plankton feeder. ''Amplectobelua species'', in contrast to ''Anomalocaris'', were smaller and had a much wider body front with eyes placed lateral to the mouth. The only plausible close relatives of the anamalocarids are the [[opabinid]]s, another group of enigmatic early forms. The anomalocarids and opabinids are usually considered to be allied to the [[arthropod]]s, but they clearly are not [[crown group]] arthropods. In some taxonomies they are placed as [[stem group]] arthropods; in others they are given their own [[phylum (biology)|phylum]], [[Dinocarida]]. Some fossils suggest that Anamalocarids and other Dinocarids share a common ancestry with Onychophora, due to the similarities in the fossils to both groups.[http://www.trilobites.info/species4.html] For example Onychophora and Dinocarid joints and segments tend not to be as well-defined and not as clearly separated as most arthropods. ==Popular Culture== The [[Pokémon]] [[Anorith]] and [[Armaldo]] are based on this creature. One of the Angels, Sandalphon, from the [[Neon Genesis Evangelion]] [[anime]] (episode 10) was modeled after these creatures. Anomalocaris, along with [[Opabinia]], was the subject of a short story by [[Neal Shusterman]]. Anomalocaris is the star of a [[Walking with Monsters]] segment. A mech designed after an anomalocaris named Accordian Hazard was featured at as one of the five different final bosses of the Taito game [[G Darius]]. ==See also== *''[[Opabinia]]'' *''[[Walking with Monsters]]'' *''[[Pambdelurion]] *''[[Kerygmachela]] == References == * Briggs, Derek; Collier, Frederick; Erwin, Douglas. ''The Fossils of the Burgess Shale''. Smithsonian Books, 1995. * James W. Valentine. ''On the Origin of Phyla''. University Of Chicago Press, 2004. * Tim Haines & Paul Chambers. ''The Complete Guide to Prehistoric Life''. BBC Books, 2005. * Conway Morris, Simon. ''The Crucible of Creation''. Oxford University Press, 1998. <references/> == External links == * [http://www.trilobites.info/anohome.html The Anomalocaris Homepage] [[Category:Burgess Shale fossils]] [[Category:Dinocarida]] [[Category:Sirius Passet fossils]] [[Category:Maotianshan shales fossils]] [[Category:Fossils]] [[Category:Cambrian animals]] [[ca:Anomalocàrid]] [[es:Anomalocárido]] [[fr:Anomalocaris]] [[ja:アノマロカリス]] [[zh:奇蝦]]