Rhenocycloceras sp.

Fig. 11

Material examined

GERMANY – Rhenish Mountains • 1 specimen; Medebach, Bromberg NW quarry; Arnsbergites falcatus Zone (Late Viséan); 2000; Korn leg.; illustrated in Fig. 11A; MB.C.32345 • 1 specimen; Herdringen, large quarry south of the town; Paraglyphioceras rotundum Zone (Late Viséan); 1976; Ebbighausen leg.; illustrated in Fig. 11B; MB.C.32346 • 1 specimen; Deinstrop, large quarry; Arnsbergites gracilis Zone (Late Viséan); 1982; Korn leg.; illustrated in Fig. 11C; MB.C.32347 • 1 specimen; In den Dieken, southern section; Neoglyphioceras spirale Zone (Late Viséan); 1976; Korn leg.; MB.C.32348 • 1 specimen; In den Dieken, southern section; Neoglyphioceras suerlandense Zone (Late Viséan); 1976; Korn leg.; MB.C.32349 • 1 specimen; Oelinghausen, 750 m SE of the monastery; Paraglyphioceras rotundum Zone (Late Viséan); 2025; Korn leg.; MB.C.32350 • 1 specimen; Herborn; “Posidonienschiefer” (Late Viséan); BGRB X13500 • 2 specimens; Aprath, Gut Steinberg; “Ob. Culmtonschiefer” (Late Viséan); 1918; Waldschmidt leg.; BGRB X13501 – BGRB X13502 • 1 specimen; Aprath, Gut Steinberg; “Ob. Kulmtonschiefer” (Late Viséan); 1920; Scholl leg.; BGRB X13503 • 1 specimen; Aprath; “Ob. Kulmtonschiefer” (Late Viséan); BGRB X13504 • 1 specimen; Marsberg; “Posidonienschiefer” (Late Viséan); 1931; Paeckelmann leg.; BGRB X13505 • 1 specimen; Eimelrod-Deisfeld; “Culmtonschiefer” (Late Viséan); BGRB X13506 • 1 specimen; Allendorf; “Kulmtonschiefer” (Late Viséan); BGRB X13507 • 2 specimens; “Hagen”; “Culmplattenkalk” (Late Viséan); 1918; Waldschmidt leg.; BGRB X5614, BGRB X13508. – Harz Mountains • 1 specimen; Bad Grund, Iberg; “Culm” (Late Viséan); BGRB X13509 • 1 specimen; Wildemann, Schwarzebach, Innerstetal; “shales in greywacke” (Late Viséan); BGRB X13510 • 1 specimen; Bad Grund, Winterberg quarry; Late Viséan; 2013; Knappe leg.; MB.C.33351.

MOROCCO – Jerada Basin • 1 specimen; Mennjel el Akhal; Late Viséan; 2006; Korn leg.; MB.C.32352.

Description

Specimen MB.C.32345 is a strongly crushed fragment (Fig. 11A), measuring approximately 95 mm in preserved length, over which the conch diameter increases from approximately 27 mm to 52 mm. The preserved portion comprises roughly two-thirds of the annulate growth stage and one-third of the unornamented adult stage. This indicates an original conch length of nearly 200 mm, with an expansion angle of 15°. Due to strong vertical deformation, the sculpture is only faintly preserved. Nevertheless, it is evident that the final regular annulus occurs at a conch diameter of approximately 35 mm, with an annuli spacing/conch diameter ratio of 0.19. In addition, a very low final annulus is present, separated from the last regular annulus by a relatively wide interspace.

Specimen MB.C.32346 is a fragment of a body chamber measuring 50 mm in length, with a conch diameter of approximately 32 mm (Fig. 11B). Although three-dimensionally preserved, the specimen is broken and does not allow for reconstruction of the conch profile. The surface bears ten straight annuli, all of which are equally developed. They are symmetrical in cross section, forming rounded ridges. Their spacing, relative to the conch diameter, is approximately 0.17. No shell material is preserved.

Specimen MB.C.32347 is a small fragment of a three-dimensionally preserved phragmocone, 22 mm in length (Fig. 11C), over which the conch diameter increases from 8.4 mm to 12.8 mm. The expansion angle is 11.5°. The specimen bears seven straight annuli, which are symmetrical in cross section and form relatively sharp ridges. Their spacing, relative to the conch diameter, is 0.24. The straight suture lines are positioned approximately in the middle of the interspaces between the annuli.

Specimen MB.C.32348 is a strongly flattened, small fragment with a conch diameter of approximately 37 mm. It exhibits relatively broad annuli, which are approximately half the width of the interspaces. Both the annuli and the interspaces display uniformly fine growth lines.

Specimen MB.C.32349 is a small, strongly flattened fragment with a conch diameter of approximately 28 mm. It shows rather narrow annuli, about one-quarter the width of the interspaces. Both the annuli and the interspaces exhibit uniformly fine growth lines.

Remarks

The specimens described and listed here under open nomenclature cannot be assigned to a specific species due to their poor preservation, strong fragmentation, or small size.