|Species||Psiloceras costosum LANGE|
Lange describes the species as identical to Ps. calliphyllum, only ribbed throughout.
The strong nodule stage is not followed by a smooth or very weakly undulating coil before the wrinkles set in, but the nodules elongate and become distinct ridges.
The cross-section of the windings is oval, the outer side is smooth.
* Description according to Lange (1952), supplemented
The continuous ribbing distinguishes the species from Ps. calliphyllum. Lange describes three variants that differ in the ribbing and also a little in the dimensions. In one variant (B) the ribs become weaker after 2-3 coils and only weak undulations are present. This makes a differentiation from Ps. calliphyllum almost impossible. Possibly some of Lange's specimens are even extreme forms of the quite variable species Ps. calliphyllum.
Psiloceras costosum occurs together with Psiloceras tenerum above the calliphyllum and below the naumanni/ johnstoni horizon.
Dimensions with D= 50mm
Nw % v. D: ca. 50%
Wh % v. D: ca. 26%
Wb % v. D: ca. 17%
- 1952 Psiloceras (Paraphylloceras) costosum sp. n. – Lange, S. 114, Taf. 14.2-4
- 2021 Psiloceras costosum LANGE – KMENT S. 248, Fig. 8.4-8.6