Gonatocyrtoceras guerichi (SOBOLEW, 1912) from
Platyclymenia Zone , Famennian in Lagow-Dule, Poland;
1. Very small adult specimen in lateral (a) and ventral (b ) views, coll. Pro f. H. MAKOWSKI.
2. Large phragmocone in lateral (a) and dorsal (b) views, ZPAL N/335.
3. Longitudinal section through a phragmocone , ZPAL N/323.
4. Adult living ch amber in lateral (a), ventral (b), and septal (c) views, ZPAL N/333.
5. Adult specimen in lateral (a) and ventral (b) views, coll. Prof. H. MAKOWSKI.

Diagnoza

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

Synonimes:

Poterloceras glirichi n, sp.; SOBOLEW 1912,  ?Gyroceras halli n. sp.; WEDEKIND 1908, ?Cyrtoceras platygaster n. sp.; BORN 1912, cf. Stereotoceras canadense FLOWER; SCHONENBERG 1952, Tritonoceras chernovi sp. nov.; ZHURAVLEVA 1972, Elaphoceras conspectum sp. nov.; ZHURAVLEVA 1972,  Elaphoceras quletum sp, nov.; ZHURAVLEVA 1972, Elaphoceras timanicum sp. nov.; ZHURAVLEVA 1972.

Porównanie

The juveniles of G. guerichi and G. holzapfeli are indistinguishable. On the average, G. guerichi 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. The form of the mature living chamber is unique and in fact, I am unaware of any similar specimens
of unquestionably different species.
Variability. - There is very wide intrapopulation variability in shell size and shape, and also in the curvature of septa.

Autekologia

Występowanie geograficzne

The topotype population from Dule is the only one recorded from Poland.
The specimens from the Famennian of the Harz which are referred to in the synonymy are very poorly preserved and their conspecificity with G. guerichi is uncertain. As judged from the three specimens thus far known, all from the Lower Frasnian of the Arctic Urals, Tritonoceras chernovi ZHURAVLEVA, 1972, does not significantly differ from G. guerichi. G. guerichi does not differfrom five specimens, all from the Upper Frasnian of Timan, assigned by ZHURAVLEVA (1972) to three species of Elaphoceras. All forms can thus represent a single evolutionary lineage.

Zasięg czasowy

Materiały muzealne

Literatura

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