| 词条 | Discoceras |
| 释义 |
| fossil_range = M-U Ordovician | name = Discoceras | image = Discoceras boreale.JPG | regnum = Animalia | phylum = Mollusca | classis = Cephalopoda | subclassis = Nautiloidea | ordo = Tarphycerida | familia = Trocholitidae | genus = Discoceras | genus_authority = Barrande, 1867 }}Discoceras is an extinct marine cephalopod mollusk, a member of the Trocholitidae in the Tarphycerida. It is distinct from Discosorus, It is characterized by closely coiled, gradually expanding shells with a subquadrate cross section, that may be ribbed or smooth. The sides are broadly rounded; the venter is wide and slightly rounded. The maximum width is slightly dorsal of the middle. The dorsum has a slight to moderate impression. The siphuncle starts off central for the first half whorl then becomes marginodorsal in the succeeding two whorls, then subdorsal at maturity. As with Trocholites, the dorsal siphuncle in Discoceras probably indicates an orientation during life that places the back of the living chamber high in the shell.[1] Discoceras has been found in Middle and Upper Ordovician sediments in Northern Europe, Baffin Island in Canada, Yunnan and Hubei provinces in China, and in Punjab, India. See also
References1. ^Discoceras, p K360 in Vol K of the Treatise on Invertebrate Paleontology in the section on the Trocholitidae, pp K359-K362, in the Chapter on the Tarphycerida by Furnish and Glenister starting with page K343. {{Taxonbar|from=Q5281576}} 11 : Nautiloids|Ordovician cephalopods|Ordovician cephalopods of Europe|Ordovician cephalopods of North America|Ordovician animals of Asia|Extinct animals of India|Middle Ordovician first appearances|Late Ordovician extinctions|Paleozoic life of Manitoba|Paleozoic life of the Northwest Territories|Paleozoic life of Nunavut |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。