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Valcouroceras
''Valcouroceras'' is the type genus for the Valcouroceratidae, a family in the nautiloid order Oncocerida named by Rousseau Flower, 1943, named for Valcour Island in Lake Champlain, between New York state and Vermont, where it was first discovered. The shell of ''Valcouroceras'' is strongly curved, more so than in ''Minganoceras'', with the lower or ventral side on the outside curve. The body, or living, chamber is gibbous, broader near the middle than at the ends. The early growth stage is laterally compressed, higher than wide, then dorsally flattened, and finally depressed, wider than high. Septal necks of the siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ... are straight, suborthochoanitic, nearly reaching he previous septa. Connecting rings start off thin but thick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valcouroceratidae
The Valcouroceratidae is a family within the Oncocerida, nautiloid cephalopods from the middle and upper Ordovician, established by Rousseau Flower in 1945. Diagnosis Valcouroceratids are characterized by exogastric cyrtocones and brevicones that change during the life span from compressed to depressed or subtriangular in cross section, and which have ventral siphuncles that are cyrtochoanitic and which contain lamellar actinosiphonate fillings. The actinosiphonate fillings, commonly referred to as deposits, are radially inward projections of the connecting rings that extend longitudinally along the inner wall of the siphuncle and project forward as blades into the siphuncle interior from the septal foramina.(Sweet 1964, Flower 1950) Distribution Most valcouroceratids come from North America but Valcouroceras has been found in northern Europe (Norway) as well. (Sweet 1964) Genera The Valcouroceratidae includes 8 genera: *'' Valcouroceras'' *'' Actinomorpha'' *'' Augustoceras'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rousseau Flower
Rousseau Hayner Flower (1913–1988) was an extremely prolific 20th century paleontologist, known for his eccentric personality. Career Although trained as an entomologist, and a specialist in dragonflies and orthopterans, Flower began studying paleontology in the middle of the 1930s. He became an expert in North American cephalopods of the Devonian period as well as the stratigraphy of the early Paleozoic era. His main field was the nautiloids, which he studied intensely, often focusing on life habits and theoretical aspects of paleobiology, but he also penned many papers on fossil corals and other invertebrates. Flower described several hundred new fossil species and over 100 new genera. Eccentricities In the paleontology community, Flower's colorful behavior earned him admirers and enemies—whom he would occasionally "thank" in the acknowledgement sections of his papers or, in one case, in the name of a fossil species. His antics included mocking the alleged low-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oncocerida
The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous; one possible member is known from the Early Permian), in which the connecting rings are thin and siphuncle segments are variably expanded (Flower, 1950). At present the order consists of some 16 families, a few of which, such as the Oncoceratidae, Brevicoceratidae, and Acleistoceratidae contain a fair number of genera each while others like the Trimeroceratidae and Archiacoceratidae are represented by only two or three (Sweet, 1964). Physical characteristics The shells of oncocerids are primarily somewhat compressed cyrtoconic brevicones. More advanced forms include gyrocones, serpenticones, torticones, and elongate orthocones and cyrtocones, reflective of the different families and genera (Flower, 1950; Sweet, 1964). The siphuncle in the Oncocerida is commonly located at or near the ventral margin. Connecting rings are mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Champlain
, native_name_lang = , image = Champlainmap.svg , caption = Lake Champlain-River Richelieu watershed , image_bathymetry = , caption_bathymetry = , location = New York/Vermont in the United States; and Quebec in Canada , coords = , type = , inflow = Otter Creek, Winooski River, Missisquoi River, Poultney River, Lamoille River, Ausable River, Chazy River, Boquet River, Saranac River, La Chute River , outflow = Richelieu River , catchment = , basin_countries = Canada, United States , length = , width = , area = , depth = , max-depth = , volume = , residence_time = 3.3 years , shore = , elevation = , islands = 80 ( Grand Isle, North Hero, Isle La Motte, '' see list'') , cities = Burlington, Vermont; Plattsburgh, New York Lake Champlain ( ; french: Lac Champlain) is a natural freshwater lake in North America. It mostly lies between the US states of New York and Vermont, but also extends north into the Canadian province of Quebec. The New York portion of the Ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vermont
Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to the north. Admitted to the union in 1791 as the 14th state, it is the only state in New England not bordered by the Atlantic Ocean. According to the 2020 U.S. census, the state has a population of 643,503, ranking it the second least-populated in the U.S. after Wyoming. It is also the nation's sixth-smallest state in area. The state's capital Montpelier is the least-populous state capital in the U.S., while its most-populous city, Burlington, is the least-populous to be a state's largest. For some 12,000 years, indigenous peoples have inhabited this area. The competitive tribes of the Algonquian-speaking Abenaki and Iroquoian-speaking Mohawk were active in the area at the time of European encounter. During the 17th century, Fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minganoceras
''Minganoceras'' is a genus in the oncocerid family, Valcouroceratidae, named by Foeste, 1938, from the Middle Ordovician of Quebec, found on Mingan Island. The shell of ''Minganoceras'' is a slender depressed exogastric cyrtocone, curved so that the underside, the venter, is longitudinally convex and the opposite side, the dorsum, is longitudinally concave. The venter is more narrowly rounded in section than the dorsum, a common feature of exogastric forms, including ''Bassleroceras'' and developed to a greater extreme in ''Kindleoceras ''Kindleoceras'' is a genus of oncocerids belonging to the Valcouroceratidae, extinct nautiloid cephalopods that lived during the Middle and Late Ordovician. ''Kindleoceras'' is characterized by a gently curved or virtually straight shell, the ...''. The siphuncle is cyrochoanitic with simple actinosiphonate deposits. References * Walter C Sweet, 1964. Nautiloidea-Oncocerida. Treatise on Invertebrate Paleontology Part K Mollusca 3. Geologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphuncle
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ''Spirula''. In the case of the cuttlefish, the siphuncle is indistinct and connects all the small chambers of that animal's highly modified shell; in the other cephalopods it is thread-like and passes through small openings in the septa (walls) dividing the camerae (chambers). Some older studies have used the term siphon for the siphuncle, though this naming convention is uncommon in modern studies to prevent confusion with a mollusc organ of the same name. Function The siphuncle is used primarily in emptying water from new chambers as the shell grows. To perform this task, the cephalopod increases the saltiness of the blood in the siphuncle, and the water moves from the more dilute chamber into the blood through osmosis. At the sam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Nautiloid Genera
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils Of Georgia (U
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 absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
