Species | Schlotheimia extranodosa (WÄHNER) |
Author | WÄHNER |
Group | Schlotheimien |
Horizon | pachygaster-horizon |
Zone | marmoreum-zone |
Stage | Upper Hettangian |
Description
Schlotheimia extranodosa has a young round, later highly oval winding cross-section. The sickle ribs are at first simple, radial and regular. They start low above the umbilical drop, become increasingly strong on the flank, end almost in nodes after the forward bend and leave only a small median furrow on the external side.
Above a certain dm, which varies greatly (50mm or more), splitting ribs appear. At the same time, the sculpture begins to weaken. The flank becomes almost completely smooth, only near the outer side the remains of the ribs are clearly visible at the bending points.
* Description according to WÄHNER 1882, supplemented
Compare
The large navel width and the simple ribs refer to the genus Schlotheimia, the weakening of the irregular ribbing on the flanks and the regularly standing external endings of the ribs are characteristic for the species S. extranodosa.
Schlotheimia extranodosa always occurs together with Angulaticeras marmoreum and is quite common in the fauna of the upper Hettangian.
Dimension
NW % v. D.: ca. 40-42%
WH % v. D.: ca. 34–36%
WB % v. D.: ca. 20-26%
Literature
- 1882 Aegoceras extranodosum – WÄHNER, S. 168, Taf. 20, 7-11
- 1963 Schlotheimia extranodosa – BLIND, S. 79, Taf. 2, 1