Paragattendorfia patens ( Vöhringer, 1960 )

Korn, Dieter & Weyer, Dieter, 2023, The ammonoids from the Gattendorfia Limestone of Oberrödinghausen (Early Carboniferous; Rhenish Mountains, Germany), European Journal of Taxonomy 882, pp. 1-230 : 33-35

Paragattendorfia patens ( Vöhringer, 1960)

Figs 20–21 ; Tables 10–11

Imitoceras patens Vöhringer, 1960: 147 , pl. 1 fig. 1, text-fig. 24.

Paragattendorfia patens – Korn 1994: 36, text-figs 31c–d, 32d, 63c; 2006: text-fig. 3g. — Sprey 2002: 52, text-fig. 17d. — Kullmann 2009: text-fig. 2.4.

Diagnosis

Species of Paragattendorfia with a conch reaching 40 mm diameter. Conch at 20 mm dm thickly pachyconic, subinvolute to subevolute (ww/dm ~0.75; uw/dm ~0.30). Whorl profile at 20 mm dm strongly depressed (ww/wh ~2.00); coiling rate very low (WER ~1.45).Venter broadly rounded, umbilical margin rounded. Growth lines fine, narrow-standing, with nearly linear course. Without constrictions on the shell surface; with linear internal shell thickenings. Suture line with narrowly V-shaped external lobe and narrowly V-shaped adventive lobe.

Material examined

Holotype

GERMANY • Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone, bed 2; Vöhringer Coll.; illustrated by Vöhringer (1960: pl. 1 fig. 1), Korn (1994: text-fig. 31c) and Korn (2006: text-fig. 3g); re-illustrated here in Fig. 20A ; GPIT-PV- 63912.

Paratypes

GERMANY • 2 specimens; Rhenish Mountains , Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 2; Vöhringer Coll.; GPIT-PV- 63914 , GPIT-PV- 63916 .

Additional material

GERMANY • 1 specimen; Rhenish Mountains , Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 3a; Korn 1991 Coll.; MB.C. 31066 • 1 specimen; Rhenish Mountains , Oberrödinghausen, railway cutting ; Hangenberg Limestone , bed 3d2; Weyer 1993–1994 Coll.; MB.C. 31067 .

Description

Holotype GPIT-PV-63912 is a moderately preserved, partly mechanically ground specimen with 22 mm conch diameter ( Fig. 20A ). It is thickly pachyconic and subinvolute (ww/dm = 0.73; uw/dm = 0.29) with a very low coiling rate (WER = 1.45). The whorl profile is crescent-shaped with a narrowly rounded umbilical margin. The suture line has a V-shaped external lobe and a symmetrical adventive lobe of almost the same shape, but it is slightly deeper. Both lobes are separated by a symmetrical, narrowly rounded ventrolateral saddle ( Fig. 21B ).

Remarks

Paragattendorfia patens is separated from P. sphaeroides by the more slender conch (ww/dm = 0.85 in P. patens but above 1.00 in P. sphaeroides at 10 mm dm) and in the wider umbilicus (uw/dm = 0.30 in P. patens but 0.20 in P. sphaeroides at 10 mm dm).

The species is rather rare in the Hangenberg Limestone. A record of “ Paragattendorfia aff. patens ” from the Montagne Noire by Becker & Weyer (2004) does not belong here; the specimen possesses a dorsal siphuncle and must be attributed to Wocklumeria . It was a Late Devonian contamination in an earliest Carboniferous assemblage ( Korn 2005).

Figures

Fig. 20. Paragattendorfia patens (Vöhringer, 1960) from the Oberrödinghausen railway cutting. A. Holotype GPIT-PV-63912 (Vöhringer Coll.) from bed 2. B. Paratype GPIT-PV-63914 (Vöhringer Coll.) from bed 2. C. Specimen MB.C.31067 (Weyer 1993–1994 Coll.) from bed 3d2. Scale bar units =1 mm.

Fig. 21. Paragattendorfia patens (Vöhringer, 1960) from the Oberrödinghausen railway cutting. A. Cross section of paratype GPIT-PV-63916 from bed 2. B. Suture line of holotype GPIT-PV-63912 from bed 2, at ww =12.4 mm, wh=6.5 mm. D–F. Ontogenetic development of the conch width index (ww/dm), umbilical width index (uw/dm), whorl width index (ww/wh) and whorl expansion rate (WER) of selected specimens. Scale bar units =1 mm.