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Endoceratidae
Endoceratidae is a family of large to very large straight shelled nautiloid cephalopods belonging to the order Endocerida that lived during the Middle and Late Ordovician. They include the largest known Paleozoic invertebrates, represented by '' Endoceras'' and ''Cameroceras''.Teichert C, (1964). Endoceratoidea; Treatise on Invertebrate Paleontology, ''Part K, Mollusca 3''.Flower R. H. (May 1958). "Some Chazyan and Mohawkian Endoceratida", ''Jour Paleo'' 32 (2) pp 433-458 Description Endocerids are characterized by large, generally ventral siphuncles with simple endocones which lack the more complex structures associated with the Proterocameroceratidae and their derivatives. Endocones, nested cone-shaped deposits characteristic of the Endocerida, form in the apical portion of the siphuncle where they balanced the weight of the animal in the body chamber at the opposite end. This helped assure a horizontal orientation while the endoceratid animal was alive. The septal necks are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocerida
Endocerida is an extinct nautiloid order, a group of cephalopods from the Lower Paleozoic with cone-like deposits in their siphuncle. Endocerida was a diverse group of cephalopods that lived from the Early Ordovician possibly to the Late Silurian. Their shells were variable in form. Some were straight (orthoconic), others curved (cyrtoconic); some were long (longiconic), others short (breviconic). Some long-shelled forms like '' Endoceras'' attained shell lengths close to . The related ''Cameroceras'' is anecdotally reported to have reached lengths approaching , but these claims are problematic. The overwhelming majority of endocerids and nautiloids in general are much smaller, usually less than a meter long when fully grown. Morphology Endocerids had a relatively small body chamber as well as a proportionally large siphuncle, which in some genera reached nearly half the shell diameter. This suggests that much of the visceral mass may have been housed within the siphuncle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piloceratidae
The Piloceratidae are a compressed, rapidly expanding, cyrtoconic brevicones with holochoanitic ventral siphuncles and simple endocones. Most likely evolved from ''Clitendoceras'', a narrow, slightly endogastric genus intermediate in form between straight shelled ''Proendoceras'' and the bulkier Piloceratidae. Found in shallow carbonate marine sediments of Demingian through the Cassinian age, (essentially Arenigian, = early Middle -Upper Canadian) . Pilocerids split off from the Proterocameroceratidae very shortly after their inception and are the first family which the proterocamerocerids gave rise to. With the exception of Humeoceras, found in the middle Silurian, pilocerid genera are limited to the Lower Ordovician (Canadian in North America). The general shape of the pilocerid shell precludes an ambush predator lying in wait on the sea floor, or a stealthful hunter drifting through the water. Rather, they probably crawled over the sea floor, head down with the shell off the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proterocameroceratidae
The ''Proterocameroceratidae'' were the first of the Endocerida. They began early in the Ordovician with ''Proendoceras'' or similar genus which had developed endocones, replacing the diaphragms of the ellesmerocerid ancestor. Proterocameroceratids are long, straight or gently curved with a generally narrow siphuncle along the ventral margin. Septal necks are short, never quite reaching the previous septum and may vary in length ontogenically within a species. Connecting rings are thick and layered. Endocones are simple, especially in early forms but may be complex with secondary structures in later forms. The Proterocameroceratidae gave rise to the Piloceratidae early on, and later to the Manchuroceratidae and Chihlioceratidae, from which the Allotrioceratidae are derived, and later yet possibly to the Emmonsoceratidae and Najaceratidae. The Piloceratidae in turn may have given rise to the Endoceratidae although a proterocameroceratid ancestor remains possible. Proterocamerocer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allocotoceras
''Allocotoceras'' is an endocerid from the Lower Ordovician (upper Canadian) Karmberg Formation of Australia (Tasmania),''Allocotoceras'' at .org included in the , based on small, straight or gently curved siphuncles. Septal necks, according to Teichert, 1964, are holochoanitic, reaching to the previous septum. Endocones are described as having a dorsal wedge, or process, making the internal opening, or endosiphocone, semicircular in cross section. In this sense ''Allocotoceras'' seems to resemble the genus '' |
Foerstellites
''Foerstellites'' is a genus of Ordovician cephalopods from North America, belonging to the family Endoceratidae, in which the siphuncle takes up the entire apex. ''Foestellites'', named by Kobayashi, 1940, is based on the apical part of the conch, or shell, which expands rapidly as septa are added. Not a true nanno type, since the siphuncle is not truly swollen at the apex. Probably the apical end of ''Cameroceras ''Cameroceras'' ("chambered horn") is a genus of extinct, giant orthoconic cephalopod that lived mainly during the Ordovician period. It first appears during the middle Ordovician, around 470 million years ago, and was a fairly common component o ...'' or '' Vaginoceras''. References * Flower, Rousseau H.1958. Some Chazyan and Mohawkian Endoceratida. Jour of Paleontology, V.32, n3, pp433–458, May 1958 * Teichert, C. 1964. Endoceratoidea, Treatise on Invertebrate Paleontology, part K. Geological Society of America and Univ. Kansas Press. Prehistoric nautiloid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chazyoceras
''Chazyoceras'' ("Horn of the Chazyan") is a moderately large endocerid included in the Endoceratidae with a ''Nanno'' type apex and a ventral siphuncle with a holochoanitic (where "holo" is entire, and "choan" refers to its funnel-shaped opening) wall, characteristic of the family. The siphuncle swelling at the apex is subtriangular in longitudinal profile. The endocones are of medium length. ''Chazyoceras'' was named by Rousseau Flower in 1958. The genotype is ''Chazyoceras valcourense'' which came from the Middle Chazyan (Lower Middle Ordovician) of Valcour Island on Lake Champlain. ''Chazyoceras'' resembles ''Perkinsoceras'' which Flower included in the Allotrioceratidae - a family which Flower named and included in the Endocerida based on the strange fossil, ''Allotrioceras ''Allotrioceras'' is a tubular fossil from the Middle Ordovician of the state of New York, collected by Rousseau H. Flower; included by him in the Endocerida and placed in a new family, the Allo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanno (cephalopod)
''Nanno'' is an extinct genus of Endocerid, named by Clarke in 1894 for the apical end of an endocerid from the Trenton Limestone of New York state that has the basic description of the nanno type (where the siphuncle swells to fill the entire apex of the shell, leaving septa and camerae to begin a few centimeters forward). It is possibly the senior synonym for ''Proterovaginoceras'' . As a valid genus, ''Nanno'' is included in the Endoceratidae Endoceratidae is a family of large to very large straight shelled nautiloid cephalopods belonging to the order Endocerida that lived during the Middle and Late Ordovician. They include the largest known Paleozoic invertebrates, represented by '' ... but the nanno type apex may be found in other families. References * Clarke, J. M. (1897)The Lower Silurian Cephalopoda of Minnesota In: E.O. Ulrich, J. M. Clarke, W. H. Scofield & N. H. Winchell ''The Geology of Minnesota. Vol. III, Part II, of the final report. Paleontology.'' Harriso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triendoceras
''Triendoceras'' is a genus of fairly large endocerid named by Flower (1958), included in the Endoceratidae by Teichert (1964), characterized by a holochoanitic ventral siphuncle in which the cross section through the endocones has an opening in the shape of an isosceles triangle with a sharp apex (corner) pointing down. ''Triendoceras'' is found in the upper Lower Ordovician of Quebec and New York in North America and possibly in Ohio, and in eastern Europe. The type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ... is ''T. montrealense''. References *Flower, R. H 1958, Some Chazyan and Mohawkian Endoceratida, Jour Paleon V 32, No 2, pp 433–458, May 1858 *Teichert, Curt 1964. Endoceratoidea; Treatise on Invertebrate Paleontology, Part K Mollusca 3; Geol Soc of America ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proterovaginoceras
''Proterovaginoceras'' (Ancient Greek for "earlier shield horn") is a medium to large sized endocerid (endocone-bearing orthoconic nautiliod) from the Early and Middle Ordovician included in the family Endoceratidae Endoceratidae is a family of large to very large straight shelled nautiloid cephalopods belonging to the order Endocerida that lived during the Middle and Late Ordovician. They include the largest known Paleozoic invertebrates, represented by '' .... ''Proterovaginoceras'' has a straight shell with a circular cross section, straight sutures, and a ventral to central, nanno-type, siphuncle which fills the entire apical part of the shell. Septal necks are macrochoanitic, up to two camerae (chambers) long; connecting rings, one chamber in length line the inside of the necks. Endocones are long and slender, fill the entire bulbous, nanno-end, of the siphuncle. ''Proterovaginoceras'' was named by Reudemann in 1905. ''Dideroceras'' Flower 1950 and ''Chisloceras'' Gorta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suecoceras
''Suecoceras'' is an endoceratid (a kind of nautiloid cephalopod) that lived during the Middle Ordovician. It is characterised by a long, straight, slender shell with a slightly expanded tip that curves slightly downwards. The shell is compressed from side to side in the humped apical portion, but circular in the rest. The siphuncle is proportionally large, 1/3 to 1/2 the shell diameter; ventral at the beginning, becoming subventral in the adult portion. Septal necks are holochoanitic to slightly maxichaonitic, extending back to the previous septum and sometimes beyond. Endocones are long and slender, with a narrow tube running down the middle. The siphuncle takes up the entire apex, but is not swollen as in ''Chazyoceras'' or ''Nanno''. A typical species, ''S. barrande'' (Dewitz), whose fossil remains are known from Sweden (hence the name, ''Sueco-'' means "Swedish"), has a shell about long. Distribution Fossils of the genus have been found in: [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
