| Species | Sunrisites hadroptychum (WÄHNER) |
| Author | WÄHNER |
| Group | Psiloceraten |
| Horizon | seebachi-horizon |
| Zone | megastoma-Zone |
| Stage | Middle Hettangian |
Description
Sunrisites hadroptychum can be easily distinguished from all other forms of Hettangium "at first sight" (quote WÄHNER): The cross-section of the coils is very thick and the ribbing extremely strong.
The winding height increases slowly at first, but then more and more with age. At the same time, however, the Wb also increases, so that the cases are always wider than high. The distinct nodule stage changes into regularly standing, broad and high ribs, which are radial. They start on the inner bend, reach the greatest height on the middle of the flank and then disappear just as quickly. A forward bend can only be observed in large specimens. There, the sculpture can also weaken considerably.
The flank is always broadly rounded, never flattened, which is why the navel is particularly deep.
A detailed description of the prairie line is given by WÄHNER (1884).
* Description according to WÄHNER 1884, supplemented
Compare
As already mentioned, confusion with other forms is hardly possible. The species of Caloceras can be similar in small diameters, but are less thick. The genus Sunrisites is represented by several species in America, alpine there is only one. Possibly S. hadroptychum is therefore an immigrant.
Sunrisites hadroptychum occurs just below the marmoreum crust together with e.g. Alsatites proaries and Alpinoceras seebachi.
Dimension
Dimensions at D= approx. 22mm:
Nw % v. D: ca. 45%
Wh % v. D: ca. 32%
Wb % v. D: > 32 %
Abmessungen bei D= ca. 132mm:
Nw % v. D: ca. 48%
Wh % v. D: ca. 27%
Wb % v. D: > 27%
Literature
- 1884 Aegoceras hadroptychum n.f. – WÄHNER S. 148, TAF. 18.1-3
- 2000 Caloceras hadroptychum WÄHNER – KMENT S.196, Taf. 2.8
