Species | Storthoceras haploptychum (WÄHNER) |
Author | WÄHNER |
Group | Psiloceraten |
Horizon | gonioptychum-horizon |
Zone | megastoma-Zone |
Stage | Middle Hettangian |
Description
After a distinct nodule stage, slightly retroradiate, slender and high ribs begin, which bend strongly forward near the external side and then quickly extinguish. The ribs meet externally in very small specimens, very soon the external side is then smooth. The winding cross-section is oval, the external side broadly rounded with a rather large winding width. The species grows quite large.
* Description according to Lange (1952), supplemented
Compare
St. haploptychum differs from St. curviornatum by the externally more pre-bent ribs, which extinguish much faster. The shells have a smooth external side at a very early stage. What remains are sharp ribs on the middle of the flank, which extinguish during the forward bending. This ribbing is quite typical for St. haploptychum.
Dimension
Dimensions with D= 45mm
Nw % v. D: ca. 45%
Wh % v. D: ca. 33%
Wb % v. D: ca. 26%
Literature
- 1882 Aegoceras haploptychum n.f. – Wähner S. 76, Taf. 17.1-5
- 1952 Strorthoceras haploptychum Wähner – Lange, S. 132, Taf. 17.1-3