orthoconicadj.
/ˌɔːθə(ʊ)ˈkɒnɪk/, U.S. /ˌɔrθoʊˈkɑnɪk/ Palaeontology.
Of a nautiloid cephalopod: having a straight (or nearly straight) conical chambered shell (orthocone). Also: designating such a shell.
ΘΚΠ
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
1926 A. F. Foerste in Jrnl. Sci. Lab. Denison Univ. 21 v. 304 (heading) Orthoconic genera.
1926 A. F. Foerste in Jrnl. Sci. Lab. Denison Univ. 21 v. 310 The specimen is figured as having its ventral side ribbed and fluted vertically in a manner very similar to that of Kionoceras, a form of ornamentation unknown in any other orthoconic triangular cephalopod.
1955 Evolution 9 249/1 The second great group of orthoconic cephalopods is the Actinoceradita.
1990 C. Pellant Rocks, Minerals & Fossils 113/1 In many early forms the shell is straight (orthoconic), but coiled shells are a characteristic feature of the sub-class.
This entry has been updated (OED Third Edition, September 2004; most recently modified version published online March 2022).
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adj.1926