11-417: The Tainoceratoidea are a superfamily in the cephalopod order Nautilida characterized by straight to loosely coiled shells, generally to a degree such that the width is greater than the height, to quadrate whorl section. Many bore spines, ribs, frills, wings, or nodes. In early forms, the siphuncle is generally near ventral, but more variable (usually central) in advanced forms. Tainoceratoids are derived from
22-818: A second decline after the Middle Silurian. After this the order declined until its extinction in the Early Carboniferous ( Mississippian ). Near the beginning of the Devonian and well before its end, the Oncocerida gave rise to the Rutoceratidae (Flower, 1976; Kümmel, 1964), which form the root stock of the Nautilida , which among its members includes the modern Nautilus and Allonautilus . Oncocerids are well known as fossils from
33-884: The Oncocerida through the Rutoceratidae which first appear in the Lower Devonian . The Rutoceratidae gave rise to the exclusively Devonian Tetragonoceratidae and early on the Mississippian or late the Devonian to the Tainoceratidae and Koninckioceratidae. The Tainoceratidae gave rise to the Rhiphaeoceratidae which are confined to the Permian. The Tainoceratoidea, established by Alpheus Hyatt in 1883, are equivalent for most purposes to
44-498: The order Oncocerida early in the Devonian . Rutoceratidae comprise a family within the oncocerid superfamily Tainocerataceae They are generally characterized by cyrtoconic and gyroconic shells, commonly with spines, nodes, or frills, although some included genera are almost orthoconic, and a commonly empty, tubular ventral siphuncle. The Rutocertids lived during the Devonian and Mississippian (early Carboniferous) and are
55-539: The Bassleroceratidae. Later in the mature stages of early forms and throughout in the more advanced the connecting rings are inflated with cyrtochoanitic septal necks, giving what can be described as a "beaded" or "ellipsoidal" appearance (Sweet, 1964). The Oncocerida are thought to be derived from the Bassleroceratidae through Graciloceras as a result of a thinning of the connecting rings in
66-708: 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). The shells of oncocerids are primarily somewhat compressed cyrtoconic brevicones. More advanced forms include gyrocones, serpenticones, torticones, and elongate orthocones and cyrtocones, reflective of
77-421: 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 most commonly thin and structureless but in certain derived forms may become actinosiphonate with inwardly projecting radial lamellae. The juvenile segments in early genera are straight and tubular, with short orthochoanitic septal necks inherited from
88-684: The later Ordovician, Silurian , and Devonian in North America, Europe, and Australia, and to a lesser extent from parts of Asia, after which the order declined into the Mississippian and reached its end by the Pennsylvanian (late Carboniferous) (Flower, 1976; Sweet, 1964). Families in the Oncocerida, according to the Treatise on Invertebrate Paleontology , follow with the number of genera in each shown in parentheses, along with
99-579: The siphuncle (Flower, 1976). Oncocerids reached their greatest generic diversity in the Middle Silurian with some 43 genera representing nine families (Sweet, 1964), the most at any time. Of these 43 or so genera, about 38 were new, a recovery from a precipitous decline in the Late Ordovician and Early Silurian . A second period of greater diversity occurred in the Middle Devonian with eight families represented by some 37 genera, following
110-443: The stratigraphic range. According to more current thinking, e.g. Flower, Teichert, and Kümmel, the Oncocerida gave rise to the Rutoceratidae which form the root stock of the Nautilida , which after a number of iterations, ends up with the modern Nautilus and Allonautilus . Rutoceratidae Rutoceratidae is a family of prototypical nautilids , derived probably from either Brevicoceratidae or Acleistoceratidae of
121-552: The suborder Rutoceratina established later by Shimanskiy in 1957. This prehistoric nautiloid -related article is a stub . You can help Misplaced Pages by expanding it . 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
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