| 翻訳と辞書 |
| Kionoceratidae ： ウィキペディア英語版 |
Kionoceratidae
Kionoceratidae is a family in the Orthocerida, proposed by Hyatt in 1900 for genera characterized by prominent ornamentation in the form of longitudinal ribs, ridges, or lirae, or combinations thereof, sometimes with similar transverse ornament or faint transverse annulations.〔Sweet 1964: Nautilodea - Orthocerida; Treatise on Invertebrate Paleontology, Part K, Mollusca 3; Teichert and Moore (eds). Univ. Kans. Press.〕
When Kionoceratidae was first conceived it contained only two genera, ''Kionoceras'' and ''Spyroceras''. ''Spyroceras'' turns out to be a number of genera in different groupings.〔Flower 1962 Notes on the Michelinoceratida, Part II Memoir 10, State Bureau of Mines and Mineral Resources, Socorro New Mexico〕 True ''Spyroceras'' is a Pseudorthoceratid from the Devonian. Middle Silurian genera related to ''Kionoceras'' studied by Barrande show a general internal similarity. Anterior siphuncle segments tend to become fusiform, some being constricted at the septal openings. Cameral deposits are confined apically and, where observed, siphonal deposits are simple annuli. While there seems to be a true relationship among the Silurian genera with similar external markings, the scope of ''Kionoceras'' itself is uncertain 〔 creating some doubt as to the establishment of a family based on such an uncertain genus. Flower sought to include Kionceras along with related genera in what he called the "already overcrowded Michelinoceratidae". Sweet (1964)〔 in the Treatise presented kionoceratids as a subfamily, the Kionoceratinae, in the orthocerid family Michelinoceratidae. Kroger and Isakar (2006)〔Kröger, Bjorn, & Isakar, Mare. (2006) Revision of annulated orthoceridan cephalopods of the Baltoscandic Ordovician. Fossil Record 9(1):137-163.〕 cast some doubt as to the validity of this subgroup. which depends on whether it consists of convergent genera with different ancestries (polyphyletic) or is a true monophyletic group with a single ancestry. Regardless it is still a useful, descriptive, grouping within the Orthocerida.
==References==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Kionoceratidae」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|