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Tokummia
''Tokummia katalepsis'' is a fossil hymenocarine arthropod from the Burgess Shale as found in a quarry in Marble Canyon in Canada, lived during middle Cambrian (508 million years old). The animal has maxillipeds, mandibles, ring-shaped around 50 body segments, and subdivided basipods. At the front of the animal, there are a pair of antennae, possible eyes and mandibles with pincers. ''Tokummia'' shows the oldest record of arthropod pincers. Carapaces had length up to long. Its biramous legs had endites (small spikes). It is suggested to be a bottom feeder, being able to walk on the sea floor, and to occasionally swim, and used its pincers to catch prey. The genus name ''Tokummia'' named after Tokumm Creek which runs through the Marble Canyon where it was found. The species name ''katalepsis'' means Greek word for "seizing", "gasping" or "holding". According to research of ''Tokummia'', Hymenocarines like ''Tokummia'', ''Branchiocaris'', ''Canadaspis'' and '' Odaraia'' are s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hymenocarina
Hymenocarina is an order of extinct arthropods known from the Cambrian. They possess bivalved carapaces, typically with exposed posteriors. Members of the group are morphologically diverse and had a variety of ecologies, including as filter feeders and as predators. Recent research has generally considered them to be stem or crown group members of Mandibulata, due the presence of mandibles in at least some species. Taxonomy Hymenocarines are characterized by the combination of following characters: bivalved, convex carapace covering cephalothoracic region; cephalothorax bearing multisegmented antennules and rounded mandibles, alongside post-maxillular limbs with spiny, subdivided basis and endopods with well-developed terminal claws; absence of appendages between antennules and mandibles; median sclerite and lobate protrusions located between compound eyes; posterior tagma (abdomen) with ring-like segments and terminated by a pair of well-developed caudal rami. Based on th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marble Canyon (Canadian Rockies)
Marble Canyon is a canyon surrounding Tokumm Creek just above its confluence with the Vermilion River, at the north end of Kootenay National Park in the Canadian Rockies of British Columbia, Canada. South of Marble Canyon on Highway 93 is Numa Falls on the Vermillion River. As described by ''Canadian Alpine Journal'' in 1913, " okumm Creekjoins Vermillion River through a magnificent gorge, or box canyon, so narrow that at several places the fissure, for it seems little more than a crack in the rock strata, is bridged by great boulders that have become wedged across it. It was a feature well worth seeing." Cambrian Lagerstatte A major new find was announced in early 2014 of fossilized Cambrian soft-bodied organisms in or near Marble Canyon that rival or even surpass the nearby Burgess Shale fossil site in size and preservation. The report said that 22% of the observed species found in the initial excavation were new to science. Additionally, several species previously known o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branchiocaris
''Branchiocaris'' is an extinct genus of Cambrian bivalved arthropod. The type and best known species, ''Branchiocaris pretiosa,'' was described from the Burgess Shale of British Columbia, Canada, in 1929, originally placed in '' Protocaris'', and was placed into its own distinct genus by Briggs in 1976. Several other possible species have been described from Cambrian deposits in China, and it is also possibly known from Cambrian deposits in Utah. ''Branchiocaris pretiosa'' is around in length, with a highly segmented trunk, consisting of at least 44 ring-like segments, terminating in a forked tail telson. At the front of the animal is a pair of short segmented tapered antennules with at least 20 segments, as well as a pair of claw appendages. It was likely an active swimmer, and used the claw appendages to bring food to the mouth. The discovery of '' Tokummia'' from the Burgess Shale, believed to be a close relative of ''Branchiocaris'', has shed light on the evolutionary plac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burgess Shale Fossils
The fossils of the Burgess Shale, like the Burgess Shale itself, formed around 505 million years ago in the Mid Cambrian period. They were discovered in Canada in 1886, and Charles Doolittle Walcott collected over 65,000 specimens in a series of field trips up to the alpine site from 1909 to 1924. After a period of neglect from the 1930s to the early 1960s, new excavations and re-examinations of Walcott's collection continue to reveal new species, and statistical analysis suggests that additional discoveries will continue for the foreseeable future. Stephen Jay Gould's book '' Wonderful Life'' describes the history of discovery up to the early 1980s, although his analysis of the implications for evolution has been contested. The fossil beds are in a series of shale layers, averaging and totalling about in thickness. These layers were deposited against the face of a high undersea limestone cliff. All these features were later raised up above current sea level during the cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Ontario Museum
The Royal Ontario Museum (ROM) is a museum of art, world culture and natural history in Toronto, Ontario, Canada. It is one of the largest museums in North America and the largest in Canada. It attracts more than one million visitors every year, making the ROM the most-visited museum in Canada. The museum is north of Queen's Park, in the University of Toronto district, with its main entrance on Bloor Street West. Museum subway station is named after the ROM and, since a 2008 renovation, is decorated to resemble the institution's collection at the platform level. Established on April 16, 1912, and opened on March 19, 1914, the museum has maintained close relations with the University of Toronto throughout its history, often sharing expertise and resources. The museum was under the direct control and management of the University of Toronto until 1968, when it became an independent Crown agency of the Government of Ontario. Today, the museum is Canada's largest field-research in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mandibulata
Mandibulata, termed "mandibulates", is a clade of arthropods that comprises the extant subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects and others). Mandibulata is currently believed to be the sister group of the clade Arachnomorpha, which comprises the rest of arthropods (Chelicerata and Trilobita). The mandibulates constitute the largest and most varied arthropod group. The name "Mandibulata" refers to the mandibles or jaws, which are the characterizing feature of its member arthropods. Molecular phylogenetic studies suggest that the living arthropods are related as shown in the cladogram below. Crustaceans do not form a monophyletic group as insects and other hexapods have evolved from within them. See also *Atelocerata *Marrellomorpha *Myriochelata *Pancrustacea *Crustaceomorpha Crustaceomorpha is a proposed clade of arthropods that includes crustaceans and numerous extinct groups. Synapomorphies for the clade are that the larval antenna is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crown gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Odaraia
''Odaraia'' is a genus of bivalved arthropod from the Middle Cambrian. Its fossils, which reach in length, have been found in the Burgess Shale in British Columbia, Canada. ''Odaraia'' bore a large pair of eyes at the front of its body, and may have had two smaller eyes in between. It had a tubular body with at least 45 pairs of biramous limbs, and its tail had three fins – two horizontal, one vertical – which were used to stabilise the animal as it swam on its back. It has been suggested to have been an actively swimming filter feeder or predator, using its limbs to capture or sift food items from the water column, before using its appendages to transfer food to its mouth. 217 specimens of ''Odaraia alata'' are known from the Greater Phyllopod Bed, where they comprise 0.41% of the community. It is currently classified as a member of Hymenocarina, a group containing many bivalved arthropods. Further reading * * References External links *''Odaraia''in the Paleobio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadaspis
''Canadaspis'' ("Shield of Canada") is an extinct genus of bivalved Cambrian arthropod, known from North America and China. They are thought to have been benthic feeders that moved mainly by walking and possibly used its biramous appendages to stir mud in search of food. They have been placed within the Hymenocarina, which includes other bivalved Cambrian arthropods. Description ''Canadaspis'' ''perfecta'' The bivalved carapaces of ''Canadaspis'' ''perfecta'' are typically in length, which taper towards the front end. The head had a small pair of eyes borne on short stalks. Between the eyes is a forward pointing spine, as well as a pair of short antennae, which appear to lack segmentation. Similar antennae are known from '' Waptia'', and are probably homologous to the hemi-ellipsoid bodies of crustaceans, and thus likely have an olfactory function. The head also has another pair of larger, segmented antennae, probably with more than 12 segments, the segments increased in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pincer (biology)
A pincer is the part of an arthropod that enables it to carry loads, to defend against other creatures, or to attack prey. In insects, the pincers are usually part of the creature's mandible, and often venom or acid can be injected through the pincer into an enemy during a pincer strike. Some arthropods such as crabs, lobsters, and scorpions possess pincers in the form of chelae at the ends of their front limbs (pedipalps), to assist in feeding, defence or even courtship. See also * Chela (organ) * Krukenberg procedure * Pedipalp * Pincer (tool) Pincers are a hand tool used in many situations where a mechanical advantage is required to pinch, cut or pull an object. Pincers are first-class levers, but differ from pliers in that the concentration of force is either to a point, or to an ... References {{reflist Arthropod anatomy ... [...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] |
Arthropod Leg
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, plural ''coxae''), ''trochanter'', ''femur'' (plural ''femora''), ''tibia'' (plural ''tibiae''), ''tarsus'' (plural ''tarsi''), ''ischium'' (plural ''ischia''), ''metatarsus'', ''carpus'', ''dactylus'' (meaning finger), ''patella'' (plural ''patellae''). Homologies of leg segments between groups are difficult to prove and are the source of much argument. Some authors posit up to eleven segments per leg for the most recent common ancestor of extant arthropods but modern arthropods have eight or fewer. It has been argued that the ancestral leg need not have been so complex, and that other events, such as successive loss of function of a ''Hox''-gene, could result in parallel gains of leg segments. In arthropods, each of the leg segments ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
