Gatunek typowy
Goniatites uniangularis Conrad, 1842 from the latest Givetian Leicester Pyrite of New York.

Opis

Diagnosis. — Involute discoidal conch with closed umbilicus; the main subventral area of the septum concave, without lateral vaultings; the first septum deeply concave and swollen.
Remarks. — The Frasnian populations of the main lineage of Tornoceras differ from those of the Givetian in a less acute outline of the ventral saddles  and from those from the early Famennian in suture lobes restricted to the subventral part of the whorl.
The septum geometry of Tornoceras is extremely simple, simpler than one may infer from the relatively complex course of the suture line. There are only concavities in the septum that fits closely the baloon model of septa. The difference between the central concavity located ventrally of the preceding whorl and concavities on its side apparently resulted from different ease of withdrawal of the body while developing a new chamber. This may have been related to the animal’s anatomy. One may guess that the internal organs of higher stiffness (liver?) occupied the ventral part of the whorl, resisting the cameral liquid pressure more than the dorsolateral parts. 

Synonimy

Zasięg czasowy

Literatura

Dzik, J. 2006. The Famennian "Golden Age" of conodonts and ammonoids in the Polish part of the Variscan sea. Palaeontologia Polonica 63, 1-359.