| 释义 |
‖ Orthoceras Palæont.|ɔːˈθɒsəræs|
Pl. orthocerata |ˌɔːθəʊsəˈreɪtə|.
[f. ortho- ‘straight’ + Gr. κέρας, pl. κέρᾱτα horn.]
An extinct genus of cephalopods, having long straight (or nearly straight) chambered shells; a fossil shell of this genus.
1830Lyell Princ. Geol. I. 101 The gigantic orthocerata of this era being, to recent multilocular shells, what the fossil ferns, equiseta, and other plants of the coal strata, are in comparison with plants now growing within the tropics. 1863― Antiq. Man xx. 404 It is said truly that the ammonite, orthoceras, and nautilus of these ancient rocks were of the tetrabranchiate division.
Hence orthoceran |ɔːˈθɒsərən| a., belonging to the Orthocerata.
1884Science III. 127/1 Evidence..that the Ammonoidea, with their distinct embryos, arose from the orthoceran stock. |