Gonatocyrtoceras guerichi (Sobolew, 1912) from Cheiloceras Zone, Famennian, Łagów-Dule, Poland; 1. Very small adult specimen in lateral (a) and ventral (b ) views, 2. Large phragmocone in lateral (a) and dorsal (b) views. 3. Longitudinal section through a phragmocone. 4. Adult living chamber in lateral (a), ventral (b), and septal (c) views.
5. Adult specimen in lateral (a) and ventral (b) views.

Gonatycyrtoceras guerichi (SOBOLEW, 1912) from Platyclymenia Zone, Famennian in Lagow-Dule, Holy Cross Mts, Poland;
 Reconstructed adult shell in lateral and ventral views, and the outline of its aperture

Diagnoza

Bulgy, exogastrically curved shell with mature living chamber decreasingadaperturally in dorsoventral diameter but expanding in width (as measured normally
to dorsoventral diameter).

Porównanie

The juveniles of G. guerichi and G. holzapfeli are indistinguishable. On the average, G. guerichi shell is much more curved than G. holzapfeli, especially in the adapical part of the mature living chamber. Typical specimens of the two species differ in their apertural form, but there are also intermediates and hence, their specific distinction is uncertain. There is very wide intrapopulation variability in shell size and shape, as well as in the convexity of septa.

Autekologia

Występowanie geograficzne

The Holy Cross Mts, possibly also the Harz in Germany. 

Zasięg czasowy

Materiały muzealne

ZPAL N/323, 333, 335

Literatura

Dzik, J. 1984. Phylogeny of the Nautiloidea. Palaeontologia Polonica 45, 1-255