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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] |
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] |
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] |
Bassleroceras
''Bassleroceras'' is an elongate upwardly curved, exogastric, genus with the venter on the under side more sharply rounded than the dorsum on the upper. The siphuncle is ventral, composed of thick-walled tubular segments in which connection rings thicken in towardly as in both the Ellesmerocerida and primitive Tarphycerida. ''Bassleroceras'' is the type genus of the Bassleroceratidae which Furnish and Glenister (1964) included in the Ellesmerocerida, but which Flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ... (1967) placed in the Tarphycerida. ''Bassleroceras'' gave rise to the Tarphycerida (sensu Furnish and Glenister, 1964) by evolving genera with tighter and tighter curvatures until becoming gyroconic, a character of the Estonioceratidae, a family of early tarphycerids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 cross section of which is triangular with flattened dorsum and subangular venter. The siphuncle is small, ventral, cyrtochoanitic with outwardly flared necks, thickened rings, and well developed radial internal actinosiphonate deposits. In general form ''Kindleoceras ''is similar to '' Manitoulinoceras'' except for its triangular cross section. '' Augustoceras'', another valcouroceratid, differs in that the rays in its actinosiphonate deposits are longer but less numerous. ''Kindleoceras'', named by Foeste, has been found in the Middle and Upper Ordovician of Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and polit ... [...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] |
