orthoconen.
/ˈɔːθə(ʊ)kəʊn/, U.S. /ˈɔrθoʊˌkoʊn/ Palaeontology.
The straight conical shell typical of early nautiloid cephalopods; a fossil having such a shell.
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the world > animals > invertebrates > subkingdom Metazoa > grade Triploblastica or Coelomata > class Cephalopoda > [adjective] > belonging to order Tetrabranchiata > relating to the nautili > of or relating to conical shell
orthocone1900
orthoconic1926
the world > animals > invertebrates > subkingdom Metazoa > grade Triploblastica or Coelomata > class Cephalopoda > [noun] > order Tetrabranchiata > family Nautilidae > member of > parts of > conical shell
orthocone1900
1900 A. Hyatt in C. R. Eastman tr. K. A. von Zittel Text-bk. Palaeontol. I. 513 An orthocone is the young of the straight as well as many of the coiled forms [of nautiloid shell].
1935 W. H. Twenhofel & R. R. Shrock Invertebr. Paleontol. ix. 368 Early cephalopod shells were dominantly straight or but slightly coiled... Among the Nautiloidea this type of shell is known as an orthocone.
1970 R. M. Black Elements Palaeontol. viii. 78 Orthoceras and similar orthocones range in length from about 3 cm to possibly 460 cm.
1991 R. Goldring Fossils in Field iv. 77 In the Palaeozoic, many orthocones had a complex siphuncle and careful collecting is required to determine this.
This entry has been updated (OED Third Edition, September 2004; most recently modified version published online March 2022).
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n.1900