"S. uniter" is known from the holotype SMNS 14216, articulated complete skeleton which was destroyed in World War II. The animal is an adult about in length. The proposed neotype is GPIT 1491/10, articulated almost complete skeleton. The animal is a young adult about in length. It was collected from the "Harpoceras falcifer" ammonoid subzones (more specifically Lias ε II10), "Harpoceras falcifer" zone, of the Posidonia Shale in Holzmaden, dating to the middle Early Toarcian stage of the Early Jurassic. Maisch referred to this species 10 additional specimens, all came from Holzmaden. They were collected from the "Harpoceras exaratum" to "H. falciferum" ammonoid subzones (Lias ε II6-II11, middle early Toarcian), "Harpoceras falcifer" zones, of the Posidonia Shale.