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Parryoceras
''Parryoceras'' is a cyrtogomphoceratid similar to ''Strandoceras'' but with broadly expanded siphuncle segments and a nearly straight ventral line. The mature shell is thickened on the inside just behind the aperture resulting in a constriction in the internal mold at the adoral end. ''Parryoceras'' comes from the middle and upper Ordovician of arctic Canada and Norway. References *Flower, Rousseau H. and Curt Teichert, 1957; The Cephalopod Order Discosorida, in University of Kansas Paleontological Contributions, Mollusca Article 6, pp 1–144 (plates, figs) July 1, 1957. *Curt Teichert 1964. Nautiloidea-Discosorida; Treatise on Invertebrate Paleontology Part K, Endoceratoidea, Actinoceratoidea, Nautiloidea. Geological Society of America. {{Taxonbar, from=Q16965709 Discosorida Prehistoric nautiloid genera Middle Ordovician first appearances Late Ordovician extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), 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 Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Union of Geological Sciences, Intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
