Species | Schlotheimia montana (WÄHNER) |
Author | WÄHNER |
Group | Schlotheimien |
Horizon | atanatense-horizon |
Zone | marmoreum-zone |
Stage | Upper Hettangian |
Description
The casings are evolute. The WQ is highly oval with a rounded external side. The flanks appear flattened, the umbilical edge is closely rounded.
The simple ribs are narrow and high, they start at the suture, run slightly retroradiate and straight across the flanks to then bend forward in a strong curve near the external side. The ribs of both sides face each other at an acute angle, leaving a central furrow (typical for Schlotheimia). They are quite numerous and never split. There is no evidence of weakening with age so far. S. montana occurs quite rarely, together with Discamphiceras atanatense in the younger marmoreum zone.
* Description according to Wähner (1884), supplemented
Compare
Schlotheimia montana is very easily distinguishable from other species: The ribs are straighter and more numerous than in S. exechoptycha and S. extranodosa, they are always simple and do not split after a certain age. The flanks are strongly flattened, quite in contrast to the thick coil cross-section of S. donar.
The most similar is S. angulata, which can also occur alpine:
dort sind aber die Nabelweite größer und die Rippen weniger zahlreich.
Dimension
Dimensions with D= 60mm (according to Wähner):
Nw % v. D: ca. 36%
Wh % v. D: ca. 37%
Wb % v. D: ca. 23%
Literature
- 1884 Aegoceras angulatum Schloth. var. montanum – Wähner S. 165, Taf, 19.1, 20.1
- 1993 Schlotheimia montana (Wähner) – Blind S. 78, Taf. 3.4