23-707: Trigonocerataceae The Trigonoceratoidea are a superfamily within the Nautilida that ranged from the Devonian to the Triassic , thought to have contained the source for the Nautilaceae in which Nautilus is found. Trigonoceratoidea are characterized by open-spiraled, gyroconic , to closed, nautiliconic shells in which the Whorl section is quadrate in primitive forms; the venter typically narrow to acute,
46-484: A large and diverse order of generally coiled nautiloid cephalopods that began in the mid Paleozoic and continues to the present with a single family, the Nautilidae which includes two genera, Nautilus and Allonautilus , with six species. All told, between 22 and 34 families and 165 to 184 genera have been recognised, making this the largest order of the subclass Nautiloidea . The current classification of
69-525: A suture with a deep, narrow, pointed ventral lobe and large pointed lateral lobes, mimicking contemporary goniatites . The Syringonautilidae , Triassic offshoots named by Johann August Georg Edmund Mojsisovics von Mojsvar , 1902, gave rise to the Nautilaceae ( Nautilina ); containing five genera, they have generally smooth, involute shells with slightly sinuous sutures and a variably positioned siphuncle. Nautilida The Nautilida constitute
92-789: Is an abridged version of Shimansky's and Flower's early schemes. Both Shimansky and Kummel derive the Nautilida from the Oncocerida with either the Acleistoceratidae or Brevicoceratidae (Teichert 1988) which share some similarities with the Rutoceratidae as the source. The Rutoceratidae are the ancestral family of the Tainocerataceae and of the Nautilida (Kummel 1964) and of Shimansky's and Teichert's Rutoceratina. The Tainocerataceae gave rise, probably through
115-734: Is narrow and tubular, is variable in position. It includes about 13 genera. Shimanskiy separated the Domatoceratidae, typified by the Permian Domatoceras , from the Grypoceratidae in the Treatise, leaving the Grypoceratidae for mostly earlier forms. The Permoceratidae , Permian offshoots named by Miller and Collinson in 1953 for the genus Permoceras , are involute, smooth, with a compressed, higher than wide, whorl section, ventrally subcentral siphuncle, and
138-440: Is open and perforate. It includes some 17 genera. The Centroceratidae , ancestral stock, proposed by Hyatt in 1900, consist of gyroconic to evolute and involute shells that have a quadrangular cross section in which the venter is much narrower that the dorsum, the venereal and umbilical shoulders usually angular, the flanks flattened and converging on the venter. Sutures form lobes on the sides and venter but are transverse across
161-685: The Permian-Triassic extinction than their distant relatives the Ammonoidea . During the Late Triassic there was a tendency in the Clydonautilaceae to develop sutures similar to those of some Late Devonian goniatites . Only a single genus, Cenoceras , with a shell similar to that of the modern nautilus, survived the less severe Triassic extinction , at which time the entire Nautiloidea almost became extinct. For
184-539: The Rutoceratidae , Tetragonoceratidae , and Centroceratidae . Nautilids declined in the Late Devonian , but again diversified in the Carboniferous , when some 75 genera and subgenera in some 16 families are known to have lived. Although there was considerable diversity in form, curved and loosely coiled shells are rare or absent, except in the superfamily Aipocerataceae . For the rest, nautilids adapted
207-779: The Aipocerataceae of Kummel (1964) in the Rutoceratina. The remaining Tainocerataceae are the Tainoceratina. Rousseau Flower (1950) distinguished the Solenochilida, Rutoceratida, and Centroceratida, as separate orders, from the Nautilida, derived from the Barrandeocerida, which are now abandoned. Within the Nautilida, he placed 10 families, included in the Nautilaceae and the no longer considered ancestral Clydonautilaceae. Teichert's 1988 classification
230-797: The Centroceratina of Shimanskiy 1957, revised to the Centrocerataceae, Shimanskiy 1962. The Trigonoceratoidea combine five families, the type, Trigonoceratidae, along with the Centroceratidae , Grypoceratidae , Permoceratidae , and Syringonautilidae . Phylogenetic study and age show that the Centroceratidae are the root stock in spite of having been first recognized 16 years after the Trigonoceratidae were first described. The Centroceratidae gave rise to
253-540: The Nautilida, in prevalent use, is that of Bernhard Kummel (Kummel 1964) in the Treatise which divides the Nautilida into five superfamilies, the Aipocerataceae, Clydonautilaceae, Tainocerataceae, and Trigonocerataceae, mostly of the Paleozoic, and the later Nautilaceae. These include 22 families and some 165 or so genera (Teichert and Moore 1964) Shimansky 1962 (in Kummel 1964) divided the Nautilida into five suborders,
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#1732779957499276-459: The Nautilidae (Nautilaceae) which contain the genus Nautilus . The Trigonoceratidae , type family, named by Hyatt, 1884, are loosely coiled to evolute , with oval to subquadrate , compressed to depressed whorl sections, and generally with longitudinal ridges or lirae . Sutures are typically slightly sinuous; the siphuncle small, subcentral, and orthochoanitic . In all the umbilicus
299-771: The Ordovician Lituites can be rejected out of hand as evolutionarily unlikely. Lituites and the Lituitidae are derived tarphycerids and belong to a separate evolutionary branch of nautilioids. The number of nautilid genera increased from the Early Devonian to about 22 in the Middle Devonian . During this time, their shells were more varied than those found in species of living Nautilus , ranging from curved (cyrtoconic), through loosely coiled (gyroconic), to tightly coiled forms, represented by
322-670: The Trigonoceratidae and Grypoceratidae in the early Mississippian , while continuing until the very Early Permian . The Trigonoceratidae which ranged into the Permian left no descendants. The Grypoceratidae which ranged almost to the end of the Triassic gave rise to two small families, the Permian Permoceratidae and the Triassic Syringonautilidae. The Syringonautilidae, in turn, are the source for
345-748: The ancestral Rutoceratidae, to the Trigonocerataceae and Clydonautiliaceae in the Devonian and to the Aipocerataceae early in the Carboniferous. The Trigonocerataceae, in turn, gave rise late in the Triassic through the Syringonautilidae to the Nautilaceae, which include the Nautilidae, with Nautilus . (Kummel 1964) The Nautilida are thought to be derived from either of the oncocerid families, Acleistoceratidae or Brevicoceratidae (Kummel 1964; Teichert 1988), both of which have
368-453: The dorsum broad. In some advanced forms, the venter may become concave or broad and rounded, and in some, the surfaces may be strongly lirate . The Trigonoceratoidea are based on the family Trigonoceratidae of Alpheus Hyatt , 1884, with which other phylogenetically related families are combined, and are equivalent to the abandoned Centroceratida of Flower in Flower and Kümmel 1950, and to
391-461: The dorsum. The siphuncle is tubular, orthochoanitic , and close to but not on the ventral margin. It includes some six genera. The Grypoceratidae , predominant stock, established by Hyatt in 1900, are characterized by generally smooth, compressed, evolute to involute shells with the venter flattened to subangular . Ornamenation is not common, but some forms bear nodes or keels. Sutures have distinct ventral and lateral lobes. The siphuncle, which
414-661: The history of life. There was a further resurgence during the Paleocene and Eocene , with several new genera, the majority of which had a worldwide distribution. During the Late Cretaceous and Early Tertiary, the Hercoglossidae and Aturiidae again developed sutures like those of Devonian goniatites. (Teichert 1988, pp. 43–44) Miocene nautilids were still fairly widespread, but today the order includes only two genera, Nautilus and Allonautilus , limited to
437-735: The mostly Paleozoic Centroceratina , Liroceratina , Rutoceratina , and Tainoceratina , and the Mesozoic to recent Nautilina . These include superfamilies which are different from those of Kummel (1964) and of less extent. The Centroceratina are comparable to the Trigonocerataceae, the Liroceratina to the Clydonautilaceae, and the Nautilina to the Nautilaceae. The main difference is that the Rutoceratidae are included with
460-678: The remainder of the Mesozoic , nautilids once again flourished, although never at the level of their Paleozoic glory, and 24 genera are known from the Cretaceous . Again, the nautilids were not as affected by the end Cretaceous mass extinction as the Ammonoids that became entirely extinct, possibly because their larger eggs were better suited to survive the conditions of that environment-changing event. Three families and at least five genera of nautilids are known to have survived this crisis in
483-641: The same sort of shells and internal structure as found in the Devonian Rutocerina of Shimanskiy, the earliest true nautilids. Flower (1950) suggested the Nautilida evolved from the Barrandeocerida , an idea he came later to reject in favor of derivation from the Oncocerida. The idea that the Nautilida evolved from straight-shelled (" Orthoceras ") nautiloids, as proposed by Otto Schindewolf in 1942, through transitional forms such as
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#1732779957499506-725: The southwest Pacific . The recent decrease in the once worldwide distribution of nautilids is now believed to have been caused by the spread of pinnipeds . From the Oligocene onward, the appearance of pinnipeds in the geological record of a region coincides with the disappearance of nautilids from that region. As a result, nautilids are now limited to their current distribution in the tropical Indo-Pacific ocean, where pinnipeds are absent. The genus Aturia seem to have temporarily survive regions where pinnipeds were present through adaptations to fast and agile swimming, but eventually went extinct as well. Predation by short-snouted whales and
529-506: The standard planispiral shell form, although not all were as tightly coiled as the modern nautilids (Teichert 1988). There was, however, a great diversity in surface ornamentation, cross section, and so on, with some genera, such as the Permian Cooperoceras and Acanthonautilus , developing large lateral spikes (Fenton and Fenton 1958). Despite again decreasing in diversity in the Permian, nautilids were less affected by
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