
Species | Partschiceras bernardii (CANAVARI) |
Author | CANAVARI |
Group | Phylloceraten |
Horizon | subsalinarius-horizon |
Zone | rotiformis-zone |
Stage | Lower Sinemur |
Description
The cross-section of the windings is highly oval, the body as a whole "very compressed", as Canavari describes it. The navel is remarkably narrow. The flanks are only very slightly curved and drop quickly to the navel without an edge. The external side is narrow but rounded.
Small specimens up to about 15mm in diameter are completely smooth.
Larger shells have recently been found that match Ph. bernardii in dimensions and coil cross-section, but are more or less ribbed:
From a diameter of approx. 15mm, fine radial to proradiate stripes appear on the outer half of the flank, which become increasingly distinct. These wrinkles also become more and more obvious on the external side. From a diameter of about 30-35mm the external side is visibly wavy. From about 50mm the ribs are also present on the inner half of the flank, although here they are particularly weak. A clear s-shaped course of the overall very flat and indistinct ribs can be seen. They seem to be irregularly strong on the flank, but regular externally. Typical Jurassic phyllites from the lower Jurassic show the same ribbing.
We assume that this is the adult stage of Ph. bernardii.
* Description according to Canavari (1882), supplemented
Compare
The narrow navel and the very small coil width make the determination unambiguous.
Dimension
Dimensions with D= 15mm
Nw % v. D: ca. 9%
Wh % v. D: ca. 57%
Wb % v. D: ca. 29%
Literature
- 1882 Phylloceras Bernardii n. sp. – Canavari, S. 151, Taf. 16.15
- 2021 Partschiceras bernardii (CANAVARI) – KMENT S. 265, Fig. 11.3