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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] |
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] |
Meniscoceras
''Meniscoceras'' is a straight and slender Chazyan endocerid described by Rousseau Flower in 1941 The genus was originally included in the Proterocameroceratidae (Flower, 1955) but later (Flower, 1976) placed with its predecessor, ''Najaceras'', in the Najaceratidae. The siphuncle in ''Mensicoceras'' is large with short septal necks and thin connecting rings. Endocones are vertically asymmetric. The central cavity is dorsally concave where a broad dorsal process is formed in which is said to contain a pair of dorso-lateral blades, and flat ventrally. ''Mensicoceras'' from the Chazy and the earlier ''Najaceras'' from the Whiterock age are similar in having a longitudual process formed along the inner dorsal side of the siphuncle around which the endocones form, but differ in details such as with the central opening. On that basis the two have been separated into their own family, the Najaceratidae (Flower 1971,1976). The ''Treatise on Invertebrate Paleontology The ''Treati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Campendoceras
''Campendoceras'' is a genus of proterocameroceratids from the Lower Ordovician of NW Australia and possibly Estonia that can be recognized by its slender, weakly endogastric, longiconic and annulate shell and large marginal siphuncle that contains endocones. The curvature in ''Campendoceras'' is less distinct than that in ''Clitendoceras'' or ''Mcqueenoceras'' and the siphuncle is larger. References * Teichert, C, 1964. Proterocameroceratidae, pp 166– 170 in the Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ... Part K. Geol Soc of America and Univ of Kansas Press. {{Taxonbar, from=Q5028259 Prehistoric nautiloid genera Ordovician cephalopods Prehistoric invertebrates of Oceania Molluscs of Oceania ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cotteroceras
''Cotteroceras'' is a genus of proterocameroceratids from the Lower Ordovician of North America and Siberia characterized by a long straight and compressed shell with very short camerae and long body chamber. Sutures are straight and oblique, sloping dorsoventrally toward the apex. The siphuncle is large but details are unknown. References * Teichert, C, 1964. Proterocameroceratidae, pp 166– 170 in the Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ... Part K. Geol Soc of America and Univ of Kansas Press. {{Taxonbar, from=Q5175598 Prehistoric nautiloid genera Ordovician cephalopods Ordovician cephalopods of North America Fossil taxa described in 1936 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mcqueenoceras
''Mcqueenoceras'' is an extinct genus of early endocerid, a nautiloid from the Floian epoch of the late early Ordovician period. It was similar in overall form to '' Clitendoceras'', from which it may have been derived. ''Mcqueenoceras'', like ''Clitendoceras'', has ventral siphuncle but the endocones are thicker on the ventral side and thinner on the dorsal. Also the sutures in ''Mcqueenoceras'' retreat rearward, forming lobes as they cross the venter. The type species is ''Mcqueenoceras jeffersonense'', named by E.O. Ulrich and A.F. Foerste in 1935, and it is known from Missouri and New York. In 1956, Rousseau H. Flower named two other species, ''M. cariniferum'' and ''M. ventrale'', both known from Maryland. References *Flower, R. H. 1964; Memoir 12, The Nautiloid Order Ellesmeroceratida (Cephalopoda), pp 126, 147, 148. NMBM&MR, Socorro N.M. *Teichert, C, 1964, ''Mcqueenoceras'', p 166 in Proterocameroceratidae, pp 166–170 in the Treatise on Invertebrate Paleontology ... [...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] |
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] |
Anthoceras
''Anthoceras'' is a genus of straight, annulated, proterocamerioceratids (Order Endocerida) from the Lower Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The ..., found in North America, NW Australia, and Siberia. The cross section is circular, the siphuncle moderately large, and marginal. Segments are constricted (producing concave profiles in internal molds); septal necks hemichoantici to subholochoantic (reaching halfway to almost to the previous septum); connecting rings thick. Endocones are long and slightly asymmetric. This genus is based on the phragmocone, the chambered part of the shell; the apical and apertural ends are unknown. See also * * References * Curt Teichert, 1964. Endoceratoidea. Treatise on Invertebrate Paleontology, Part K. Geol Soc. of Ame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clitendoceras
''Clitendoceras'' is a genus of cephalopods in the order Endocerida from the Lower Ordovician (m-u Canadian) with an elongate shell with a slight downward, endogastric, curvature and a siphuncle that lies along the ventral margin. Common for endocerids, the chambers are short and the septa close spaced with sutures sloping forward across the back of the shell. Septal necks are short in the young, lengthening in the adult. Endocones are simple, but with the ventral side of the last formed projecting forward. The endosiphotube running down the middle is arched on top and somewhat flat on the lower side. ''Clitendoceras'' appears early in the Domingian stage, Lower Ordovician, probably derived from '' Proendoceras'', and is the likely ancestor of the mostly compressed and breviconic pilocerids as well as of more similar forms such as ''Mcqueenoceras ''Mcqueenoceras'' is an extinct genus of early endocerid, a nautiloid from the Floian epoch of the late early Ordovician period. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proterocameroceras
''Proterocameroceras'' is an early Endocerid from the upper Lower Ordovician belong to the 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. Proterocamerocerat ..., characterized by a rather large, straight, longiconic shell, short chambers, generally straight sutures, and large ventral siphuncle with short septal necks, thick complex connecting rings, and endocones with three endosiphuncular blades toward the apex. ''Proterocameroceas'' has been found in N America, Greenland, Siberia, and Australia References * Curt Teichert, 1964. Endoceratoidea. Treatise on Invertebrate Paleontology, Part K. Geol Soc. of America and Univ of Kansas press. Teichert and Moore (eds) {{Taxonbar, from=Q7251558 Fossils of Greenland Nautiloids Ordovician cephalopods Fossils of Russia Prehistor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobendoceras
''Lobendoceras'' is a proterocameraceratid with a rather large, moderately expanded, straight shell with a large marginal siphuncle in which sutures have a broad, deep, ventral lobe and septal necks are subholochoanitic to holochoanitic. Lobendoceras has been found in Lower Ordovician marine strata in NW Australia and Siberia. See also *List of nautiloids References * Curt Teichert, 1964. Endoceratoidea. Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ..., Part K. Geol Soc. of America and Univ of Kansas press. Teichert and Moore (eds) * Teichert and Glenister 1954 . Early Ordovician cephalopod fauna from northwestern Australia. Bulletins of American Paleontology 35 (150): 7–112. {{Taxonbar, from=Q6663651 Prehistoric nautiloid genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
