| Species | Geyeroceras leptophyllum (HAUER) |
| Author | HAUER |
| Group | Phylloceraten |
| Horizon | subsalinarius-horizon atanatense-horizon |
| Zone | rotiformis-zone marmoreum-zone |
| Stage | Lower Sinemur Upper Hettangian |
Description
The turn cross-section is rounded trapezoidal, the umbilical edge is relatively broadly rounded, the outer side as well. The umbilical drop is vertical. The increase in winding width is remarkably rapid, it is greatest at the outer edge. The flanks are clearly flattened, quite typical for the genus Geyeroceras. No ribbing can be observed.
* Description according to Tomas & Palfy (2007), supplemented
Compare
This species differs from Geyeroceras cylindricum by the wider umbilicus and the larger diameters of the shells found. G. leptophyllum differs from Geyeroceras subcylindricum (which, together with Ps. calliphyllum, occurs much earlier in the profile!) by the much greater increase in thickness and the trapezoidal cross-section of the coils. G. subcylindricum has more or less parallel flanks.
Similar is Calaiceras calais MGH. but with less flattened flanks and especially constrictions.
Dimension
Dimensions with D= 75mm
Nw % v. D: ca. 14%
Wh % v. D: ca. 52%
Wb % v. D: ca. 49%
Literature
- 1866 Ammonites leptophyllus n.sp. – Hauer, S. 192
- 2007 Geyeroceras leptophyllum (HAUER) – Tomas & Palfy, S. 233, Taf. 2.a-b
- 2021 Geyeroceras leptophyllum (HAUER) – KMENT S. 267, Fig. 8.6
