Stroboceras sp.

Korn, Dieter & Bockwinkel, Jürgen, 2022, Early Carboniferous nautiloids from the Central Sahara, southern Algeria, European Journal of Taxonomy 831, pp. 67-108 : 84

Stroboceras sp.

Fig. 13 , Table 7

Material examined

ALGERIA • 1 specimen; Sebkha de Timimoun 14.5 km west-southwest of Timimoun (locality TIM-C8); Argiles de Timimoun supérieur (Upper Bollandoceras Assemblage ; early to middle Viséan); Korn et al. 2002 Coll.; illustrated in Fig. 13 ; MB.C.30460 .

Description

The only specimen present is a phragmocone fragment consisting of three chambers ( Fig. 13A ). It has, at 10.5 mm whorl height, a depressed pentagonal whorl profile (ww/wh = 1.44). It shows a prominent, rounded ventrolateral shoulder accompanied by shallow longitudinal grooves. The centre of the venter is shallowly convex and the umbilical margin separates the weakly convex flank from the almost flat umbilical wall by a low ridge ( Fig. 13B ). A narrow, very shallow concave whorl zone is present. The suture line shows a course dependent on the outline of the whorl profile; saddles lie in the inflated areas of the profile and lobes in the indented ones ( Fig. 13C ). Therefore, the external lobe appears trilobate and the ventrolateral saddle is raised. An internal lobe is induced by the concave whorl zone.

Figures

Fig. 13. Stroboceras sp. from Timimoun, specimen MB.C.30460 (Korn et al. 2002 Coll.). A. Ventral and lateral views. B. Whorl profile. C. Suture line, at ww =14.3 mm, wh =10.3 mm. Scale bar units=1 mm.