| Species | Discamphiceras pleuronotum (COCCHI) |
| Author | COCCHI |
| Group | Psiloceraten |
| Horizon | seebachi-horizon |
| Zone | megastoma-Zone |
| Stage | Middle Hettangian |
Description
The forms grouped under the genus "Discamphiceras" differ from Storthoceras or Megastomoceras by the highly oval winding cross-section with steep umbilical wall and distinct umbilical edge. The navel width is predominantly small. D. pleuronotum is the most widely forked species of Discamphiceras.
The distinct nodule stage on the innermost coils merges into regular, low ribs. They are slightly retroradiate and few in number. They are highest on the middle of the flank and turn forward near the outer side. Mostly, however, they disappear before. In larger cases, only a corrugation of the flattened flank can be observed, which can be seen in almost all discampicerates.
* Description according to WÄHNER (1883), supplemented
Compare
D. pleuronotum differs from other discamphicerates by the larger navel width. The navel edge in connection with the low, irregular ribs characterise the species.
Small, young specimens are very difficult to distinguish from those of the Storthoceras/ Megastomoceras group. There has not yet been a detailed study and comparison.
D. pleuronotum grows quite large. Diameters of 100mm or more are not uncommon. The form is very common in the upper megastoma zone and can be used well as a leading ammonite. It occurs together with Alsatites proaries, among others.
Dimension
Dimensions at D= 70mm (according to Wähner):
Nw % v. D: ca. 39%
Wh % v. D: ca. 36%
Wb % v. D: ca. 23%
Literature
- 1883 Aegoceras pleuronotum Cocchi – WÄHNER S. 110, Taf. 13.3
- 2000 Discamphiceras pleuronotum Cocchi – Kment S. 198
