| Species | Megastomoceras berchta (WÄHNER) |
| Author | WÄHNER |
| Group | Psiloceraten |
| Horizon | curviornatum-horizon |
| Zone | megastoma-Zone |
| Stage | Middle Hettangian |
Description
The winding cross-section is oval, the flanks only slightly curved. The low ribs are slightly retroradiate and die out very soon near the external side. In good condition, one can see that the ribs still bend forward and possibly even meet externally. The external side is broadly rounded.
The lobe line is strongly slit, corresponding to Megastomoceras megastoma. The relationship is therefore given.
Megastomoceras berchta is very rare.
* Description (after Wähner 1883, supplemented)
Compare
At first sight one thinks to have found a Psiloceras: the ribs appear simple, the navel width is large. In the stratigraphic level, however, caution is advised!
The large umbilical width in connection with the complicated lobe line and the very weak ribbing clearly characterise M. berchta.
Other wide-nibbed species like Megastomoceras paltar or M. polystreptum are much more strongly ribbed.
Dimension
Dimensions with D= 45mm
Nw % v. D: ca. 48%
Wh % v. D: ca. 29%
Wb % v. D: ca. 22%
Literature
- 1883 Aegoceras Berchta n.f. – Wähner, S. 120, Taf. 23.6
