| Species | Psiloceras ex gr. tilmanni LANGE |
| Author | LANGE |
| Group | Psiloceraten |
| Horizon | tilmanni-horizon |
| Zone | tilmanni-zone |
| Stage | Lower Hettangian |
Description
In the calliphyllum bank of the Karwendel Mountains, ammonites can rarely be found which, on the basis of the growth conditions and the ornamentation, must be placed in the vicinity of Psiloceras tilmanni LANGE, although this species would have to be searched for much deeper in the profile. It must be assumed that these are relocated shells. Accordingly, some of them are poorly preserved.
The medium-evolute shells grow quite slowly, the WQ is oval. The external side is broadly rounded and the flanks are almost flat. The umbilical edge is rounded and the umbilical wall is flat. Specimens in which the innermost convolutions were well preserved have never been found. A nodule stage can therefore only be assumed. The surface is almost smooth, distinct ribs are not present. Low radiate elevations can be observed (8 to 10 elevations on half of the last turn), but are only visible under strong oblique light. The suspensory lobes are strongly recurved which clearly speaks for the genus Psiloceras.
* Description according to Hillebrandt & Kment (2015), supplemented
Compare
The rolling up of the shells is very similar to that of Psiloceras tilmanni LANGE described from Peru and lies within the variability of this species (HILLEBRANDT 2000). Different may be in the alpine finds: The flanks are a little less curved, the umbilical angle and wall are more distinct, the sutural line is more branched. The sutural line of the alpine P. ex gr. tilmanni is very similar to that of P. strongolum and P. calliphyllum.
Similar are occasional specimens of Euphyllites with the irregular, faint undulation of the living chamber and the same lack of fold-like ridges on the flanks of the living chamber. Euphyllites, however, only occurs in the naumanni/johnstoni horizon and has particularly clearly flattened flanks.
Dimension
Dimensions with D= 75mm
Nw % v. D: ca. 38%
Wh % v. D: ca. 35%
Wb % v. D: ca. 20%
Literature
- 1917 Psiloceras planorbis – Tilmann S. 648, Taf. 22.1
- 1925 Psiloceras tilmanni – Lange, S. 474
- 2000 Psiloceras tilmanni LANGE – Hillebrandt S. 173, Taf. 11.1-20, 12.1-10, 13.1-24, 14.1-10
- 2015 Psiloceras sp. A ex gr. Psiloceras tilmanni LANGE – Hillebrandt & Kment S. 291, Taf. 13.1-2, 13.6
