Shevyrevites shevyrevi Teichert & Kummel, 1973

Korn, Dieter, Hairapetian, Vachik, Ghaderi, Abbas, Leda, Lucyna, Schobben, Martin & Akbari, Amir, 2021, The Changhsingian (Late Permian) ammonoids from Baghuk Mountain (Central Iran), European Journal of Taxonomy 776, pp. 1-106 : 19-21

Shevyrevites shevyrevi Teichert & Kummel in Teichert et al., 1973

Fig. 17 ; Table 2

Shevyrevites shevyrevi Teichert & Kummel in Teichert et al., 1973: 410, pl. 3 figs 1–3, 6.

Bernhardites radiosus – Shevyrev 1965: 171, pl. 21 fig. 7; 1968: 86, pl. 1 fig. 7, pl. 2 fig. 1.

Shevyrevites shevyrevi – Bando 1979: 133, pl. 5 figs 1, 5, pl. 8 figs 6–7. — Korn et al. 2019: 46, text- figs 11–12.

non Shevyrevites shevyrevi – Zhao et al. 1978: 107, pl. 11 figs 2–4, 6–7.

Diagnosis

Species of Shevyrevites with conch reaching 70 mm dm. Subadult stage with oval, compressed whorl profile (ww/wh= 0.70–0.90) and rounded venter; 30 coarse ribs per volution.Adult stage with rectangular and compressed whorl profile (ww/wh =0.70–0.80), flattened flanks, flattened venter and subangular ventrolateral shoulder; coarse and sharp ribs on the flank, venter smooth. Prongs of external lobe usually bifid; altogether 20–25 notches of E, A and L lobes.

Type material

Holotype IRAN • East Azerbaijan, Ali Bashi Mountains ; Ali Bashi Formation; illustrated by Teichert & Kummel in Teichert et al. (1973: pl. 3 figs 1–2); MCZ 9678 .

Material examined

IRAN • 30 specimens; Esfahan Province, Baghuk Mountain 1 section; Hambast Formation; MB.C.29664 to MB.C.29669 • 4 specimens; Esfahan Province, Baghuk Mountain B section ; Hambast Formation; MB.C.29670 to MB.C.29673 • 12 specimens; Esfahan Province, Baghuk Mountain E section ; Hambast Formation; MB.C.29674 to MB.C.29678 • 2 specimens; Esfahan Province, Baghuk Mountain G section ; Hambast Formation; MB.C.29679 • 33 specimens; Esfahan Province, Baghuk Mountain H section ; Hambast Formation; MB.C.29680 to MB.C.29687 • 92 specimens; Esfahan Province, Baghuk Mountain ; Hambast Formation; MB.C.29688 to MB.C.29712 .

Description

There is little morphological variation in the material when the conch proportions are regarded. specimen MB.C.29674 is an incomplete but comparatively well-preserved specimen with 52 mm diameter ( Fig. 17A ). It is extremely discoidal (ww/wh =0.24) and evolute (uw/dm =0.48) with a compressed, parallel-sided whorl profile with flat venter and an angular ventrolateral shoulder. The sculpture consists, on the last volution of the phragmocone as well as the body chamber, of sharp and slightly sigmoidal ribs on the flanks; on half a volution around 20 of such ribs can be counted.

The suture line of specimen MB.C.29674 has a short external lobe with concave flanks and bifid prongs ( Fig. 17D ). The ventrolateral saddle is asymmetric and appears dorsally inclined. The adventive lobe is semicircular in shape with twelve small notches of equal size. In contrast to this is the lateral lobe almost flat at its base; it is also serrated by numerous small notches.

There is some variation in the shape of the venter. In contrast to specimen MB.C.29674, the other two figured specimens MB.C.29672 ( Fig. 17B ) and MB.C.29670 ( Fig. 17C ) show a less flattened or even a rounded venter. These two specimens do not show as sharp ribs as specimen MB.C.29674.

Remarks

Shevyrevites shevyrevi differs from S. nodosus in the lack of the coarse nodes of the subadult stage and from S. corrugatus sp. nov. in the much coarser and less numerous ribs.

Stratigraphic range

Upper part of the Hambast Formation; 5.20 to 4.70 m below the extinction horizon ( Shevyrevites shevyrevi Zone ).

Figures

Fig. 17. Shevyrevites shevyrevi Teichert & Kummel in Teichert et al., 1973. A. Lateral and dorsal view, specimen MB.C.29674, section E, float. B. Lateral and dorsal view, specimen MB.C.29672, section B, float. C. Lateral and dorsal view, specimen MB.C.29670, section B, float. D. Suture line, specimen MB.C.29674, at 10.8 mm ww, 13.0 mm wh. E. Whorl profile proportions. Abbreviations: see Material and methods. Scale bar units =1 mm.