Rodzaj Prolobites
Gatunek typowy Opis Diagnosis. — Mature living chamber with hood-like apertural part delimited by whorl constriction and internal shell thickening. Remarks. — A troublesome aspect of the taxonomy within this genus is the tremendous difference in size of mature specimens co-occurring in the same bed. It remains unclear whether these are different species, different sexual morphs within the same species, or just a very wide population variability. It is noteworthy that in the most prolific Prolobites sample known in literature, from the locality Kara Dzhar in the southern Urals more than 600 specimens of P. delphinus are associated with 350 specimens of minute P. nanus. This suggests the sexual dimorphism but in the very rich sample from Kattensiepen in the Rhenish Slate Mountains minute prolobitids are apparently missing. Rare associated specimens classified in four other species differ from each other in more or less ovoid shape of the last chamber and extension to maturity of the juvenile characters, that is open umbo and simplified suture. These may represent end-members of the populations variability of P. delphinus. The material available to me is too small to decide on this. 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. |
|