| Species | Gonioptychoceras gonioptychum WÄHNER |
| Author | WÄHNER |
| Group | Psiloceraten |
| Horizon | gonioptychum-horizon |
| Zone | megastoma-Zone |
| Stage | Middle Hettangian |
Description
After a very strong nodule stage, high, straight ribs set in. They run almost radially over the flanks and then turn sharply forwards. They are therefore only slightly retroradiate. The ribs reach their greatest height at the point of bending, then weaken and end in the keeled outer side.
The coils are circular when young, then increasingly oval, and a distinct keel is present early on. This is more distinct than just a sharpening of the external side and is very reminiscent of the keel of early alpinocerates.
* Description according to Lange (1952), supplemented
Compare
The species is distinguished from Megastomoceras & Storthoceras by the keeled external side and the strong ribs, which are highest near the external side.
G. sebanum has a smaller umbilical width and more clearly retroradiate ribs. G. progastor has a much higher coil width.
Of all three Gonioptychoceras representatives, G. gonioptychum has the lowest ribs.
Moreover, the species seems to occur only after the other two together with M. megastoma. All are very rare, so that no definite statements are possible (yet).Moreover, the species seems to occur only after the other two together with M. megastoma. All are very rare, so that no definite statements are possible (yet).
Dimension
Dimensions with D= 40mm (according to Lange)
Nw % v. D: ca. 39%
Wh % v. D: ca. 35%
Wb % v. D: ca. 32%
Literature
- 1886 Psiloceras gonioptychum n.f. – Wähner S. 203, Taf. 27.5
- 1952 Gonioptychoceras goniotychum Wähner – Lange, S. 149, Taf. 17.12-13
