Sosioceras is an Upper Permian shouchangoceratin

Shouchangoceratinae

Shouchangoceratinae is one of three ammonoid subfamilies of the family Pseudohaloritidae, which in turn is one of two families in the Goniatitid superfamily Pseudohaloritaceae. The Shouchangoceratinae ammonoids were found in marine environments throughout the world during the Permian, particularly...

 pseudohaloritid characterized by a subdiscoidal shell, about 2 cm in diameter, marked by growth lines, as with Neoaganides

Neoaganides

Neoaganides is a small, 1–2 cm diameter subdiscoidal to subglobular goniatitid belonging to the family Pseudohaloritidae that lived from the Late Pennsylvanian to the Late Permian, existing for some 56 million years....

, and having a mature peristome with a double constriction near the perifery. The suture also closely resembles that of Neoaganides.

Sosioceras is found in the Upper Permian Sosio limestone of Sosio valley, in Sicily, first described by Gemmellaro, 1880, as Brancoceras pygmaeum, thought be be a rare element of the Sosio fauna. Miller and Furnish, 1957, redefined it as Neoaganides pygmaeum (Gemmellero) on the basis of close similarity of size, form, and suture to Neoaganides grahamensis. Based on features of the peristome and recognition of a wrinkle layer, unique in this family, Frest et al, 1981, renamed the genus Sosioceras, in reference to its location, arguing for its separation. The type and only species is Sosioceras pygmaeum (Gemmellero, 1880).