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Musacaris
''Musacaris '' is an extinct genus of Cambrian arthropod from the Orsten Lagerstätte, formerly synonymous with ''Martinssonia''. It contains only a single species, ''Musacaris gerdgeyeri''. Description ''Musacaris'' is a small (roughly 0.8 mm long), unsegmented arthropod, with four pairs of appendages. It has a pair of antennae, and three pairs of biramous appendages. It also has an unusual projection on its head, possibly the future position of the mouth. The unsegmented body suggests all current specimens of ''Musacaris'' may be so-called "head larvae". The five developmental stages are quite similar, with the same amount and positioning of the limbs. Currently, ''Musacaris'' is thought to be a basal mandibulate or stem-crustacean, possibly sister to labrophorans (Crustacea and Phosphatocopina Phosphatocopina (alternatively Phosphatocopida) is an extinct group of bivalved arthropods known from the Cambrian period. They are generally sub-milimetric to a few millimetr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Martinssonia
''Martinssonia'' is an extinct genus of Cambrian arthropod from the Orsten Lagerstätte. Description ''Martinssonia'' is a small (roughly 1.5 mm long) arthropod, with eight pairs of appendages and ten segments including the eyeless head. It has a pair of antennae, twelve biramous appendages on its head and front two body segments and a final pair of uniramous appendages on its third segment. ''Martinssonia'' also seems to have a pleotelson The telson () is the hindmost 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 account of ..., similar to modern crustacean larvae. Ecology ''Martinssonia'' was presumably a benthic detritivore, stirring up food particles from the seafloor. Etymology ''Martinssonia'' is named for Anders Martinsson, a former Professor of Palaeobiology at Uppsala University in Sweden. The specie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orsten
The Orsten fauna are fossilized organisms preserved in the Orsten lagerstätte of Cambrian (Late Miaolingian to Furongian) rocks, notably at Kinnekulle and on the island of Öland, all in Sweden. The initial site, discovered in 1975 by Klaus Müller and his assistants, exceptionally preserves soft-bodied organisms, and their larvae, who are preserved uncompacted in three dimensions. The fossils are phosphatized and silicified, thus the delicate chitinous cuticle and soft parts are not affected by acids, which act upon the limestone nodules within which the fossils have survived. Acids dissolve the limestone, revealing the microfossils in a recovery process called "acid etching". To recover the fossils, more than one and a half tons of Orsten limestone have been dissolved in acid, originally in a specifically designed laboratory in Bonn, more recently moved to Ulm. The insoluble residue is scanned by electron microscope. The phosphorus used to replace the fossils with calcium p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mandibulata
The clade Mandibulata constitutes one of the major subdivisions of the phylum Arthropoda, alongside Chelicerata. Mandibulates include the crustaceans, myriapods (centipedes and millipedes, among others), and all true insects. The name "Mandibulata" refers to the mandibles, a modified pair of limbs used in food processing, the presence of which are characteristic of most members of the group. The mandibulates are divided between the extant groups Myriapoda (millipedes and centipedes, among others) and Pancrustacea (including crustaceans and hexapods, the latter group containing insects). Molecular phylogenetic studies suggest that the living arthropods are related as shown in the cladogram below. Crustaceans do not form a monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in life on Earth; prior to the Period, the majority of living organisms were small, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it was not until the Cambrian that fossil diversity seems to rapidly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metamerism (biology), metameric) Segmentation (biology), segments, and paired jointed appendages. 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. They form an extremely diverse group of up to ten million species. Haemolymph is the analogue of blood for most arthropods. An arthropod has an open circulatory system, with a body cavity called a haemocoel through which haemolymph circulates to the interior Organ (anatomy), organs. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. They have ladder-like nervous systems, with paired Anatomical terms of location#Dorsal and ventral, ventral Ventral nerve cord, nerve cord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagerstätte
A Fossil-Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that preserves an exceptionally high amount of palaeontological information. ''Konzentrat-Lagerstätten'' preserve a high concentration of fossils, while ''Konservat-Lagerstätten'' offer exceptional fossil preservation, sometimes including preserved soft tissues. ''Konservat-Lagerstätten'' may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying the decomposition of both gross and fine biological features until long after a durable impression was created in the surrounding matrix. ''Fossil-Lagerstätten'' spans geological time from the Neoproterozoic era to the present. Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan shales and Burgess Shale, the Ordovician Soom Shale, the Silurian Waukesha Biota, the Devonian Hunsrück Slates and Gogo Formation, the Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antenna (biology)
An antenna (plural: antennae) is one of a pair of appendages used for Sensory system, sensing in arthropods. Antennae are sometimes referred to as ''feelers''. Antennae are connected to the first one or two Segmentation (biology), segments of the arthropod head. They vary widely in form but are always made of one or more jointed segments. While they are typically sensory organs, the exact nature of what they sense and how they sense it is not the same in all groups. Functions may variously include sensing tactition, touch, air motion, heat, vibration (sound), and especially insect olfaction, smell or gustation, taste. Antennae are sometimes modified for other purposes, such as mating, brooding, swimming, and even anchoring the arthropod to a substrate (biology), substrate. Larval arthropods have antennae that differ from those of the adult. Many crustaceans, for example, have free-swimming larvae that use their antennae for swimming. Antennae can also locate other group members i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biramous
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, : ''coxae''), ''trochanter'', ''femur'' (: ''femora''), ''tibia'' (: ''tibiae''), ''tarsus'' (: ''tarsi''), ''ischium'' (: ''ischia''), ''metatarsus'', ''carpus'', ''dactylus'' (meaning finger), ''patella'' (: ''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 articulates with the next seg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Academia
An academy (Attic Greek: Ἀκαδήμεια; Koine Greek Ἀκαδημία) is an institution of tertiary education. The name traces back to Plato's school of philosophy, founded approximately 386 BC at Akademia, a sanctuary of Athena, the goddess of wisdom and Skills, skill, north of Ancient Athens, Athens, Greece. The Royal Spanish Academy defines academy as scientific, literary or artistic society established with public authority and as a teaching establishment, public or private, of a professional, artistic, technical or simply practical nature. Etymology The word comes from the ''Academy'' in ancient Greece, which derives from the Athenian hero, ''Akademos''. Outside the city walls of Athens, the Gymnasium (ancient Greece), gymnasium was made famous by Plato as a center of learning. The sacred space, dedicated to the goddess of wisdom, Athena, had formerly been an olive Grove (nature), grove, hence the expression "the groves of Academe". In these gardens, the philos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacea
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans ( oligostracans and multicrustaceans). The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese spider ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatocopina
Phosphatocopina (alternatively Phosphatocopida) is an extinct group of bivalved arthropods known from the Cambrian period. They are generally sub-milimetric to a few millimetres in size. They are typically only known from isolated carapaces, but some found in Orsten-type phosphatized preservation have their bodies preserved in high fidelity in three dimensions. Description The phosphatized bivalved carapace covered the entire body. Members typically grew to a maximum of in length, though ''Cyclotron'' grew up to . In some species, spines were present on the carapace. The head either bore a pair of stalked eyes or a pair of dome-shaped medial eyes. The first appendage pair, dubbed the " antennulae", were uniramous, with the remaining appendage pairs being biramous. The basipods and endopods of the biramous limbs had prominently developed endites, while the exopods were typically annulated, and bore setae. The earliest larval stages of phosphatocopines are known as "head larv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Arthropods
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa, Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new Convergent boundary, convergent plate boundaries and Volcanic arc, continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in Life, life on Earth; prior to the Period, the majority of living organisms were small, Unicellular organism, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
