| Species | Megastomoceras anisophyllum (WÄHNER) |
| Author | WÄHNER |
| Group | Psiloceraten |
| Horizon | curviornatum-horizon |
| Zone | megastoma-Zone |
| Stage | Middle Hettangian |
Description
After a distinct nodule stage, strong, strongly retroradiate ribs begin to bend forward near the external side and become extinguished. Only in very small specimens can this ribbing be easily observed. The larger the shells become, the more the forward bending of the ribs disappears. What remains are strongly retroradiate, low folds. The cross-section of the coils is oval with curved flanks and a broadly rounded external side. Like all Megastomoceras, the species grows very large.
* Description according to Wähner (1882), supplemented
Compare
M. anisophyllum (Figs. 9, 10) cannot be distinguished from St. haploptychum or M. megastoma on the basis of the shell dimensions. Whereas the ribs of St. haploptychum still clearly cross the external ridge and only disappear in front of the external side, in M. anisophyllum there is hardly any ribbing visible on the external ridge. The ribs are characteristically retroradiate. The suture is more complex than in St. haploptychum.
Dimension
Dimensions with D= 50mm
Nw % v. D: ca. 44%
Wh % v. D: ca. 33%
Wb % v. D: ca. 24%
Literature
- 1882 Aegoceras anisophyllum n.f. – Wähner S. 79, Taf. 18.7, 19.1-3
- 1952 Storthoceras (Megastomoceras) anisophyllum Wähner – Lange, S. 136, Taf. 17.7
