Taouzites acutus ( Matern, 1931 )

Korn, Dieter & Bockwinkel, Jürgen, 2022, The early gephuroceratid ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea), European Journal of Taxonomy 823, pp. 10-47 : 32-34

Taouzites acutus ( Matern, 1931)

Fig. 15

Pharciceras acutum Matern, 1931: 88 , pl. 2 fig. 8.

Taouzites acutus – Korn & Klug 2002: 99.

Diagnosis

Species of Taouzites reaching about 60 mm conch diameter with extremely discoidal, involute conch at 30 mm dm (ww/dm ~ 0.30; uw/dm ~ 0.10); coiling rate very high (WER ~ 2.40). Whorl profile strongly compressed (ww/wh ~ 0.55); umbilical wall oblique and flattened, venter sharply acute. Growth lines very fine, strongly biconvex. Suture line with wide external lobe, high, narrow median saddle, pointed E

2

and E

4

lobes and rounded lateral and umbilical saddles and lobes.

Material examined

Holotype GERMANY • Rhenish Mountains , Oberscheld (“Tiefe Grube”); late Givetian (Red Ironstone); Etzold 1910 Coll.; MB.C.3664 . Illustrated by Matern (1931: pl. 2 fig. 8), re-illustrated here in Fig. 15A .

Paratype GERMANY • Rhenish Mountains , Oberscheld (“Tiefe Grube”); late Givetian (Red Ironstone); Etzold 1910 Coll.; MB.C.30430 .

Additional material

GERMANY • 1 specimen; Rhenish Mountains , Oberscheld (Grube Königszug); late Givetian (Red Ironstone); Krecke 1903 Coll.; MB.C.22193 .

Description

Two specimens are selected for description and illustration:

Holotype MB.C.3664: slightly deformed specimen with 29 mm conch diameter in tuffitic ironstone ( Fig. 15A ).

MB.C.22193: fragmentary specimen with 56 mm diameter in haematitic, micritic limestone.

Holotype MB.C.3664 has a thinly discoidal and involute conch with very high coiling rate ( Fig. 15A ). The whorl profile strongly compressed; the umbilical wall is very shallow and the flanks converge towards the acute venter that possesses a fine keel. Rather coarse growth lines with biconvex course are visible on the flanks; they extend with a low dorsolateral projection and a high, narrow ventrolateral projection. The suture line possesses a wide, parallel-sided external lobe, a V-shaped lateral lobe, a small and V-shaped U 2 lobe and a shallow, rounded U 4 lobe ( Fig. 15B ).

Remarks

Taouzites acutus resembles T. taouzensis from the Anti-Atlas but, at a comparable diameter (30 mm) the conch dimensions are different in T. taouzensis with ww/dm = 0.25, uw/dm = 0.15, ww/wh = 0.45, WER = 2.60.

Figures

Fig. 15. Taouzites acutus (Matern, 1931). Holotype MB.C.3664 (Etzold 1910 Coll.) from Oberscheld (“Tiefe Grube”). A. Lateral view and dorsal projection. B. Suture line, at dm ca 9 mm, ww = 3.0 mm, wh = 4.5 mm. Scale bar units = 1 mm.