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Balhuticaris
''Balhuticaris'' is a genus of extinct bivalved (referring to the carapace) hymenocarine arthropod that lived in the Cambrian aged Burgess Shale in what is now British Columbia around 506 million years ago. This extremely multisegmented (with over 100 segments) arthropod is the largest member of the group, and it was even one of the largest animals of the Cambrian, with individuals reaching lengths of 245 mm (9 in). Fossils of this animal suggests that gigantism occurred in more groups of Arthropoda than had been previously thought. It also presents the possibility that bivalved arthropods were very diverse, and filled in a lot of ecological niches. The hymenocarines were an order of primitive mandibulates, the arthropod group that includes crustaceans, insects, myriapods and their relatives, that lived throughout the Cambrian period. This group was extremely diverse and attained a wide variety of ecological niches and body plans. Several dozen species are known f ... [...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 ... [...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 onl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nervous System
In Biology, biology, the nervous system is the Complex system, highly complex part of an animal that coordinates its Behavior, actions and Sense, sensory information by transmitting action potential, signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in Ediacara biota, wormlike organisms about 550 to 600 million years ago. In vertebrates it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves or ''Efferent nerve fiber, efferent'' nerves, while those nerves that transmit information from the body to the CNS a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arch
An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it. Arches may be synonymous with vaults, but a vault may be distinguished as a continuous arch forming a roof. Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture, and their systematic use started with the ancient Romans, who were the first to apply the technique to a wide range of structures. Basic concepts An arch is a pure compression form. It can span a large area by resolving forces into compressive stresses, and thereby eliminating tensile stresses. This is sometimes denominated "arch action". As the forces in the arch are transferred to its base, the arch pushes outward at its base, denominated "thrust". As the rise, i. e. height, of the arch decreases the outward thrust increases. In order to preserve arch action and prevent coll ... [...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, 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 art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuzoia
''Tuzoia'' (from Mount Tuzo, a mountain in the Canadian Rockies) is an extinct genus of large bivalved arthropod known from Early to Middle Cambrian marine environments from what is now North America, Australia, China, Europe and Siberia. The large, domed carapace reached lengths of , making them amongst the largest known Cambrian arthropods. Description The largest carapaces of ''Tuzoia'' are known to reach in length, suggesting a total body length of approximately . Along the sides of the carapace a spiked ridge is present, and the edges and midline of the carapace are also spiked in many species. These spines likely functioned to aid stability while swimming. The carapaces are marked with a reticulate (net-like) pattern, which was likely to increase the structural integrity of the valves while remaining lightweight. The head had a anterior/ocular sclerite at the top, a single pair of large stalked eyes, and a pair of segmented antennae. The head has pairs of cephalic appen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nereocaris
''Nereocaris'' is an extinct genus of bivalved hymenocarine arthropod that lived in the Cambrian aged Burgess Shale in what is now British Columbia around 506 million years ago. Two species are known. History and nomenclature The holotype and paratype were found in the Burgess Shale Läggerstatte, in the Tulip Beds; it was later described in 2012, by Legg ''et al,'' as a basal hymenocarine, naming the type species ''Neroecaris exilis.'' In 2013, a second ''Nereocaris briggsi'' was described by Legg and Caron. The generic name, ''Nereocaris'' comes from Greek: , Nereus the Greek god of waves; and , "shrimp" or "crab", meaning "Nereus's shrimp". The specific name ''exilis'' comes from Latin, meaning slim; while the second species' name ''briggsi'' means "of Briggs", referring to professor Derek Briggs Derek Ernest Gilmor Briggs (born 10 January 1950) is an Irish palaeontologist and taphonomist based at Yale University. Briggs is one of three palaeontologists, along ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carapace
A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron. Crustaceans In crustaceans, the carapace functions as a protective cover over the cephalothorax (i.e., the fused head and thorax, as distinct from the abdomen behind). Where it projects forward beyond the eyes, this projection is called a rostrum. The carapace is calcified to varying degrees in different crustaceans. Zooplankton within the phylum Crustacea also have a carapace. These include Cladocera, ostracods, and isopods, but isopods only have a developed "cephalic shield" carapace covering the head. Arachnids In arachnids, the carapace is formed by the fusion of prosomal tergites into a single plate which carries the eyes, ocularium, ozopores (a pair of openings of the scent gland of Opilione ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalan Language
Catalan (; autonym: , ), known in the Valencian Community and Carche as '' Valencian'' ( autonym: ), is a Western Romance language. It is the official language of Andorra, and an official language of three autonomous communities in eastern Spain: Catalonia, the Valencian Community, and the Balearic Islands. It also has semi-official status in the Italian comune of Alghero. It is also spoken in the Pyrénées-Orientales department of France and in two further areas in eastern Spain: the eastern strip of Aragon and the Carche area in the Region of Murcia. The Catalan-speaking territories are often called the or "Catalan Countries". The language evolved from Vulgar Latin in the Middle Ages around the eastern Pyrenees. Nineteenth-century Spain saw a Catalan literary revival, culminating in the early 1900s. Etymology and pronunciation The word ''Catalan'' is derived from the territorial name of Catalonia, itself of disputed etymology. The main theory suggests ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmography
The term cosmography has two distinct meanings: traditionally it has been the protoscience of mapping the general features of the cosmos, heaven and Earth; more recently, it has been used to describe the ongoing effort to determine the large-scale features of the observable universe. Traditional usage The 14th-century work '''Aja'ib al-makhluqat wa-ghara'ib al-mawjudat'' by Persian physician Zakariya al-Qazwini is considered to be an early work of cosmography. Traditional Hindu, Buddhist and Jain cosmography schematize a universe centered on Mount Meru surrounded by rivers, continents and seas. These cosmographies posit a universe being repeatedly created and destroyed over time cycles of immense lengths. In 1551, Martín Cortés de Albacar, from Zaragoza, Spain, published ''Breve compendio de la esfera y del arte de navegar''. Translated into English and reprinted several times, the work was of great influence in Britain for many years. He proposed spherical charts and men ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
