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Projovellania
''Projovellania'' is an extinct nautiloid cephalopod belonging to the oncocerid family Jovellaniidae found in mid Silurian sediments in Europe. The shell is a longiconic cyrtocone, like that of ''Jovellania ''Jovellania'' is a genus of extinct prehistoric nautiloids from the order Oncocerida known from the Lower Devonian of Europe (France, Germany).Sweet, W. C. (1964). "Nautiloidea -Oncocerida". '' Treatise on Invertebrate Paleontology''. Part K Nau ...'' or '' Mixosiphonoceras'', except for being compressed rather than depressed. References * Sweet W.C. 1964. Nautiloidea-Oncocerida. Treatise on Invertebrate Paleontology, Part K. Geological Society of America and Univ. of Kansas press. Teichert & Moore, (eds) {{Taxonbar, from=Q7249501 Prehistoric nautiloid genera Oncocerida ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jovellaniidae
Jovellaniidae was established as a family within the Oncocerida to include genera characterized by longiconic orthocones and cyrtocones with a subtriangular to depressed cross-section in which the ventral (siphuncular) side is typically angular or more acutely rounded than the dorsal (antisiphuncular) side, and in which the siphuncle is generally large, ventral, and with lamellar actinosiphonate deposits (Flower 1950, Sweet 1964) Jovelaniids have a range that extends from the Middle Silurian to the Upper Ordovician and are known from North America Europe. (Sweet 1964) They are thought to be derived from the 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 tha .... Jovellaniidae was given its name by Foord in 1888; its type is the genus '' Jovellania'' References * Fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods (myriapods, arachnids and hexapods) became fully terrestrialized. A significant evolutionary milestone during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautiloidea
Nautiloids are a group of marine cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species. They flourished during the early Paleozoic era, when they constituted the main predatory animals. Early in their evolution, nautiloids developed an extraordinary diversity of shell shapes, including coiled morphologies and giant straight-shelled forms ( orthocones). Only a handful of rare coiled species, the nautiluses, survive to the present day. In a broad sense, "nautiloid" refers to a major cephalopod subclass or collection of subclasses (Nautiloidea ''sensu lato''). Nautiloids are typically considered one of three main groups of cephalopods, along with the extinct ammonoids (ammonites) and living coleoids (such as squid, octopus, and kin). While ammonoids and coleoids are monophyletic clades with exclusive ancestor-descendant rela ... [...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] |
Jovellania
''Jovellania'' is a genus of extinct prehistoric nautiloids from the order Oncocerida known from the Lower Devonian of Europe (France, Germany).Sweet, W. C. (1964). "Nautiloidea -Oncocerida". '' Treatise on Invertebrate Paleontology''. Part K Nautiloidea, Teichert & Moore (eds) Nautiloids form a broad group of shelled cephalopods that were once diverse and numerous but are now represented by only a handful of species in two genera. ''Jovellania'' was named by Bayle (1879) and is type genus for the Jovellaniidae, a family assigned to the Oncocerida by Flower (1950)Flower, R. H & Kummel, B. (September 1950). "A Classification of the Nautiloidea". '' Journal of Paleontology''. 24 (3). Morphology ''Jovellania'' can be described as having a slowly widening, straight or slightly cytoconic shell with faint undulations and nearly circular or slightly depressed cross-section Kroger, B. (March 2008). "Nautiloids Before and During the Origin of Ammonoids ...". '' Special Papers in Palaeonto ... [...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] |
