| 词条 | Tetragonoceratidae |
| 释义 |
| fossil_range = {{Fossil range|Middle Devonian}} | image = | regnum = Animalia | phylum = Mollusca | classis = Cephalopoda | subclassis = Nautiloidea | ordo = Nautilida | superfamilia = Tainocerataceae | familia = Tetragonoceratidae | familia_authority = Flower, 1945 }} The Tetragonoceratidae is a small family of nautilitids constituting a part of the superfamily Tainocerataceae in which shells are coiled with a generally quadrate whorl section. Coiling is either gyroconic or evoluute with a slight dorsal impression. Flanks diverge from the umbilical to the ventral shoulders so as to make the whorl sections widest close to the venter. Nodes made develop on the flanks and shoulders. The siphuncle is tubular, typically found near the venter. Sutures are with lateral lobes and may possess dorsal and ventral lobes as well. The Tetragonoceratidae, which is an early offshoot of the Rutoceratidae, contains three genera (as of 1964), all confined to the Middle Devonian: Tetragonoceras, Nassauoceras, and Wellsoceras. References
4 : Nautiloids|Middle Devonian first appearances|Middle Devonian extinctions|Taxa named by Rousseau H. Flower |
| 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。