|
''Lituites'' is an extinct nautiloid genus from the Middle Ordovician and type for the Lituitidae (a tarphycerid family) that in some more recent taxonomies has been classified with the orthocerids and listed under the order Lituitida. Fossils have been found in New York, Argentina, Norway, Sweden, Estonia, and China. ''Lituites'' produced a shell with a planospirally coiled juvenile portion at the apex, reflective of its tarphycerid ancestry, followed by a long, moderately expanding, generally straight, orthoconic adult section with a subdorsal siphuncle connecting the chambers. The adult body chamber may equal or exceed the length of the chambered part of the orthoconic section. The mature aperture has a pair of pronounced ventrolateral lappets and a similar but shorter pair of dorsolateral lappets. ''Lituites'' gives its name to the term "lituiticone" which refers to a shell that is coiled in the early growth stage and later becomes uncoiled. == References == *Flower & Kummel, 1950. A Classification of the Nautiloidia. Jour Paleontology, V.24, N.5, pp 604-616, Sept *Furnish & Glenister, 1964, Nautiloidea -Tarphycerida. Treatise on Invertebrate Paleontology Part K... Nautiloidea *Mutvei, H. 2002. Connecting ring structure and its significance for classification of the orthoceratid cephalopods. Acta Palaeontologica Polonica 47 (1): 157–168. 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「Lituites」の詳細全文を読む スポンサード リンク
|