| 名稱 直角石化石 | Name Orthoceras Fossil |
| 地質年代 / | Geological Age / |
| 描述 直角石是一屬已滅絕的鸚鵡螺類。它的殼形為細長的柱狀椎體，稱爲“直角石式殼”，由間距緊密的凹凸腔室組成。中央是住室，其次是連接各腔的連室細管。殼表面有很多幼細的細褶襞。多種其他相似的物種都被分類在米契林角石屬中。雖然直角石的外殼像鸚鵡螺，但卻應該更爲接近蛸亞綱。直角石化石分佈於歐洲地區，可追溯至奧陶紀至三疊紀。 | Description Orthoceras is a genus of extinct nautiloid cephalopod. These are slender, elongate shells with the middle of the body chamber transversely constricted, and a subcentral orthochoanitic siphuncle. The surface is ornamented by a network of fine lirae. Many other very similar species are included under the genus Michelinoceras. Orthocera Fossil’s distribution is in Europe. and it can be traced back to Middle Ordovician. |
| 地點 / | Location / |
| 參考 Reference | |
| 編者 由 3E (2) 陳凱進 於4/6/2018編寫 _________ 於17/1/18最後編改 | Editor Created by 3E (2) Chan Hoi Tsun on 4/6/2018 Last modified by ________ as on 17/1/2018 |
