Species | Analytoceras articulatum (SOWERBY) |
Author | SOWERBY |
Group | Lyctoceraten |
Horizon | atanatense-horizon |
Zone | marmoreum-zone |
Stage | Upper Hettangian |
Description
Analytoceras articulatum has a circular coil cross-section and very characteristic constrictions on the innermost coils.
As in many lytocerates, the individual coils hardly overlap at all. The shell is smooth, large specimens may have nodes or spines according to Wähner. We have not been able to find such forms so far.
Small specimens are relatively common, medium-sized ones very rare.
* Description according to Lange (1952), supplemented
Compare
Pleuracanthites biformis is similarly dimensioned, but can be clearly delimited on the basis of the lobe line and because of the lack of constrictions (compare WÄHNER, 1890, p. 240).
Eolytoceras is also very rarely found in this horizon. However, these forms are either ribbed (Eolytoceras tasekoi) or more oval in cross-section.
Dimension
Dimensions with D= 75mm
Nw % v. D: ca. 40%
Wh % v. D: ca. 35%
Wb % v. D: ca. 35%
Literature
- 1890 Lytoceras articulatum Sow. (Orb.) – Wähner S. 255, Taf. 54.3, 58.1-5, 59.1-15, 60.1-2
- 1993 Analytoceras articulatum Sowerby – Rakus & Lobitzer S. 924
- 2000 Analytoceras articulatum Sowerby – Kment S. 194