Vermiceras aff. ophioides (D´ORBIGNY)

Description Compare Dimension Literature Images

Species	Vermiceras aff. ophioides (D´ORBIGNY)
Author	D´ORBIGNY
Group	Arieten
Horizon	rotiformis-horizon subsalinarius-horizon
Zone	rotiformis-zone
Stage	Lower Sinemur

Description

Already Wähner is not sure of the definite assignment to "Arietites" ophioides D'Orbigny. His present specimens come from the rotiforme fauna of Enzesfeld, which is undoubtedly somewhat younger than the marmoreum fauna. The ammonites occurring in the Karwendel, which have to be placed close to Vermiceras ophioides, are all somewhat narrower.
Characteristic for this species is the sculpture with straight, mostly radial ribs, which are highest near the external side, where they bend forward and go out. The ribs do not form nodes at the point of bending, as can occur in other arietitids described by WÄHNER from Enzesfeld. Shallow furrows and a strong keel are present on medium sized specimens, only a keel without furrows is present on the inner coils. The cross-section of the coils is round to oval when young, and highly oval when old.

* Description according to Wähner and Kment (2000), supplemented

Compare

Vermiceras (Epammonites) cordieri is very similar.
However, the ribs are more numerous in V. ophioides and the secondary keels are not quite as strong.
The keel formation with strong furrows starts much earlier in V. (E.) cordieri.
The winding cross-section of Vermiceras (Epammonites) cordieri is rather flattened, which is especially evident in large specimens. V. ophioides, on the other hand, is rather small in size.
V. ophioides differs from the Paracaloceras species by its numerous, straight ribs.