| Species | Storthoceras circacostatum (WÄHNER) |
| Author | WÄHNER |
| Group | Psiloceraten |
| Horizon | gonioptychum-horizon |
| Zone | megastoma-Zone |
| Stage | Middle Hettangian |
Description
Characteristic for species identification is the ribbing:
The ribs are strong and rounded and run slightly retroradiate over the flanks. Near the external side they bend only slightly forward and meet externally at a very obtuse angle, hardly weakened. With a dm of 46mm Wähner counts 36 ribs.
The cross-section of the coils is oval, the lobe line relatively simple (similar to St. extracoststum or St. curviornatum).
* Description according to Wähner (1882), supplemented
Compare
The most similar are Storthoceras curviornatum and Storthoceras extracostatum.
In both, however, the forward bend of the ribs is much stronger and the ribs are more "dashing", i.e. narrower and higher.
St. extracostatum also has more numerous ribs, St. curviornatum is more narrow-boned.
Dimension
Dimensions with D= 45mm
Nw % v. D: ca. 41%
Wh % v. D: ca. 36%
Wb % v. D: ca. 28%
Literature
- 1882 Aegoceras circacoststum n.f. – Wähner S. 83, Taf, 16.5
- 1952 Storthoceras circacostatum (WÄHNER) – Lange, S. 132, Taf. 16.2-4
