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Asaphida Genera
Asaphida is a large, morphologically diverse order of trilobites found in marine strata dated from the Middle Cambrian until their extinction during the Silurian. Asaphida contains six superfamilies (Anomocaroidea, Asaphoidea, Cyclopygoidea, Dikelocephaloidea, Remopleuridoidea and Trinucleioidea), but no suborders. Asaphids comprise some 20% of described fossil trilobites. In 2020, the superfamily Trinucleioidea was proposed to be raised to an order ( Trinucleida) and removed from Asaphida. Morphology The Asaphids generally have cephalon (head) and pygidium (tail) parts similar in size, and most species have a prominent median ventral suture. Heads are often flat, and carapace furrows in the head area are often faint or not visible. Thoracic segments typically number 5 - 12, though some species have as few as two and some as many as 30. They also generally have a wide doublure, or rim, that surrounds the cephalon. This causes some specimens to be described as having a charact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asaphus Lepidurus
''Asaphus'' () is a genus of trilobites that is known from the Lower (upper Arenig) and Middle Ordovician of northwestern Europe (Sweden, Estonia, Saint Petersburg Area). Etymology The generic name is derived from the Greek word ''asaphes'', meaning "indistinct." Description The headshield (or Trilobite#Cephalon, cephalon) and tailshield (or Trilobite#Pygidium, pygidium) are semicircular and without a border (defined by a furrow or a change in convexity parallel to its margin). The cephalon is of approximately equal size as the pygidium (or Pygidium#Trilobites, isopygous). The central raised area of the cephalon (or Trilobite#Cephalon, glabella) is long, reaching the frontal margin. It may have faint lateral glabellar furrows or be smooth, and sometimes an inconspicuous tubercle is present just in front of the hardly discernible occipital ring. The natural fracture lines (sutures) of the head run along the top edges of the compound eye. From the back of the eye these cut t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalon (arthropod Anatomy)
The cephalon is the head section of an arthropod. It is a tagma, i.e., a specialized grouping of arthropod segments. The word cephalon derives from the Greek κεφαλή (kephalē), meaning "head". Insects In insects, ''head'' is a preferred term. The insect head consists of five segments, including three (the labial, maxillary and mandibular) necessary for food uptake, which are altogether known as the gnathocephalon and house the suboesophageal ganglion of the brain, as well as the antennal segment, and an ocular segment, as well as a non segmented fused section of the head where the archicerebrum is housed known as the acron. See also arthropod head problem. Chelicerates and crustaceans File:Cherax warsamsonicus - ZooKeys 660 151-167 (cropped).jpg, The crustacean '' Cherax warsamsonicus'' File:Phrynus asperatipes.jpg, The amplypygid chelicerate '' Phrynus asperatipes'' In chelicerates and crustaceans, the cephalothorax is derived from the fusion of the cephalo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Damghan Ampyx Ghobadipour Fossil From Lashkark Formation, Ordovician, Damghan, Iran
Damghan () is a city in the Central District of Damghan County, Semnan province, Iran, serving as capital of both the county and the district. It is east of Tehran on the high-road to Mashad, at an elevation of . Damghan is one of the oldest cities on the Iranian plateau, stretching back 7,000 years, and boasts many sites of historic interest. The oldest of these is Tappeh Hessar, lying to the southeast of the city, which holds the ruins of a castle dating from the Sasanian Empire. The Tarikhaneh is one of the oldest mosques in Iran, built as a fire temple during the Sassanid dynasty, it was converted into a mosque after the advent of Islam. There are also many other historical buildings belonging to the Seljuk Empire and other periods. Apart from its historical interest, the city today is mainly known for pistachios and paper almonds (''kaghazi'') with very thin shells. History Tepe Hissar Archaeological excavation has shown that the history of Damghan starts 4–5 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment
Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension (chemistry), suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification. Sediments are most often transported by water (fluvial, fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and stream channel, river channel deposits are examples of fluvial transport and deposition (geology), deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east. Europe shares the landmass of Eurasia with Asia, and of Afro-Eurasia with both Africa and Asia. Europe is commonly considered to be Boundaries between the continents#Asia and Europe, separated from Asia by the Drainage divide, watershed of the Ural Mountains, the Ural (river), Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea, and the waterway of the Bosporus, Bosporus Strait. "Europe" (pp. 68–69); "Asia" (pp. 90–91): "A commonly accepted division between Asia and Europe ... is formed by the Ural Mountains, Ural River, Caspian Sea, Caucasus Mountains, and the Black Sea with its outlets, the Bosporus and Dardanelles." Europe covers approx. , or 2% of Earth#Surface, Earth's surface (6.8% of Earth's land area), making it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders of Russia, land borders with fourteen countries. Russia is the List of European countries by population, most populous country in Europe and the List of countries and dependencies by population, ninth-most populous country in the world. It is a Urbanization by sovereign state, highly urbanised country, with sixteen of its urban areas having more than 1 million inhabitants. Moscow, the List of metropolitan areas in Europe, most populous metropolitan area in Europe, is the capital and List of cities and towns in Russia by population, largest city of Russia, while Saint Petersburg is its second-largest city and Society and culture in Saint Petersburg, cultural centre. Human settlement on the territory of modern Russia dates back to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saint Petersburg
Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland on the Baltic Sea. The city had a population of 5,601,911 residents as of 2021, with more than 6.4 million people living in the Saint Petersburg metropolitan area, metropolitan area. Saint Petersburg is the List of European cities by population within city limits, fourth-most populous city in Europe, the List of cities and towns around the Baltic Sea, most populous city on the Baltic Sea, and the world's List of northernmost items#Cities and settlements, northernmost city of more than 1 million residents. As the former capital of the Russian Empire, and a Ports of the Baltic Sea, historically strategic port, it is governed as a Federal cities of Russia, federal city. The city was founded by Tsar Peter the Great on 27 May 1703 on the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volkhov River
The Volkhov ( ; ; ) is a river in Novgorodsky District, Novgorodsky and Chudovsky Districts of Novgorod Oblast and Kirishsky District, Kirishsky and Volkhovsky Districts of Leningrad Oblast in northwestern Russia. The Volkhov River, Volkhov, which forms part of the basin of the Neva, is the only outflow of Lake Ilmen, and connects it with Lake Ladoga. The length of the Volkhov is , and the area of its drainage basin is . The city of Veliky Novgorod, the towns of Kirishi, Volkhov and Novaya Ladoga, and the historically important village of Staraya Ladoga are located along the Volkhov. Etymology A number of etymologies, none universally accepted, have been proposed for the name of the river. In his ''Etymological dictionary of the Russian language'', Max Vasmer doubted some philologists' opinion that the river's name is related to the Finnish ''velho'' ("magician") or Russian ''volkhv'' ("pagan priest"). Geography The Volkhov flows out of Lake Ilmen north into Lake Ladoga, the la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asaphus Kowalewskii
''Asaphus kowalewskii'' () is one of the 35 species of trilobites of the genus ''Asaphus'' (this particular species is sometimes placed in its own genus, ''Neoasaphus''). Fossils of this species are popular among collectors because of their prominent stalked eyes (termed "peduncles"), many an inch or more in length. In the Ordovician period, an inland sea formed in what is now Eastern Europe. The sea contained a remarkably diverse trilobite fauna. Over a dozen species of ''Asaphus'' developed in this sea, with many species, including unrelated species, developing long eyestalks in various lengths. That so many species of trilobite developed eyestalks suggests that they were trying to overcome increased turbidity, or there was some sort of massive selective pressure leading these trilobites to bury themselves in the substrate up to their eyes. This species may have lain in wait buried in a benthic layer of loose debris or sediment with only its periscope eyestalks protruding ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
