Eocanites brevis ( 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 : 199-201

Eocanites brevis ( Vöhringer, 1960)

Figs 121–122 ; Tables 115–116

Protocanites supradevonicus brevis Vöhringer, 1960: 172 , pl. 6 fig. 5, text-fig. 46a.

Protocanites (Eocanites) supradevonicus brevis – Weyer 1965: 458, pl. 6 fig. 5.

Eocanites brevis – Korn 1994: 81, text-figs 73c, 75b. — Korn et al. 2003b: 1125, text-fig. 3a.

Diagnosis

Species of the genus Eocanites with a conch reaching 50 mm diameter. Conch at 12 mm dm evolute (uw/dm ~0.50) with weakly compressed whorl profile (ww/wh ~0.90) and broadly rounded venter; conch at 30 mm dm evolute (uw/dm ~0.50) with weakly compressed whorl profile (ww/wh ~0.85) and broadly rounded venter. Ornament with coarse, strongly rursiradiate, concavo-convex growth lines with moderately deep ventral sinus; without ribs.

Material examined

Holotype

GERMANY • Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 3c ; Vöhringer Coll.; illustrated by Vöhringer (1960: pl. 6 fig. 5) and Korn (1994, text-fig. 73c); re-illustrated here in Fig. 121A ; GPIT-PV- 63985 .

Paratypes

GERMANY • 1 specimen; Rhenish Mountains , Oberrödinghausen, railway cutting; Hangenberg Limestone,bed3a;Vöhringer Coll.;GPIT-PV-63983 • 1specimen;Rhenish Mountains,Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 3c; Vöhringer Coll.; GPIT-PV-63987.

Additional material

GERMANY • 1 specimen; Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , loose material; Korn 1990 Coll.; MB.C. 31236 • 5 specimens; Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 3a; Weyer 1993–1994 Coll.; MB.C. 31237.3–5 • 1 specimen; Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 3c 1; Weyer 1993–1994 Coll.; MB.C. 31238 • 3 specimens; Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 3d1 ; Weyer 1993–1994 Coll.; MB.C. 31239.1–3 .

Description

Holotype GPIT-PV-63985 is a completely shell-covered specimen of 18 mm conch diameter ( Fig. 121A ). It is extremely discoidal and evolute (ww/dm ~0.22; uw/dm ~0.50) with a compressed oval whorl profile (ww/wh ~0.80). The ornament consists of rather coarse growth lines, which are directed backwards on the inner flank half and describe a radial course on the outer flank half; the ventral sinus is rather shallow and broadly rounded ( Fig. 122B ).

The cross section of paratype GPIT-PV-63987 allows the study of the conch ontogeny from the initial stage to a diameter of 27 mm ( Fig. 122A ). All stages larger than 2 mm dm are very similar in shape with almost static umbilical width and coiling rate ( Fig. 122C, E ); however, the whorl profile becomes continuously narrower (from ww/wh ~1.50 at 2 mm dm to ~0.85 at 27 mm dm; ( Fig. 122D ).

Remarks

Eocanites brevis resembles E. nodosus , but has considerably weaker growth lines and no spiral lines. Eocanites brevis is separated from E. delicatus sp. nov. by the compressed whorl profile (ww/wh ~ 0.80 in E. brevis but ~ 0.90 in E. delicatus at about 40 mm dm) and from E. planus by the wider umbilicus (uw/dm ~ 0.50 in contrast to less than 0.45 in E. planus ).

Figures

Fig. 121. Eocanites brevis (Vöhringer, 1960) from the Oberrödinghausen railway cutting. A. Holotype GPIT-PV-63985 (Vöhringer Coll.) from bed 3c. B. Specimen MB.C.31238 (Weyer 1993–1994 Coll.) from bed 3c1. Scale bar units= 1 mm.

Fig. 122. Eocanites brevis (Vöhringer, 1960) from the Oberrödinghausen railway cutting. A. Cross section of paratype GPIT-PV-63987 (Vöhringer Coll.) from bed 3c. B. Growth line course of holotype GPIT-PV-63985 (Vöhringer Coll.) from bed 3c, at dm = 17.6 mm, ww =4.2 mm, wh= 5.0 mm. C–E. 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.