Shevyrevites nodosus ( Shevyrev, 1965 )

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 : 21-22

Shevyrevites nodosus ( Shevyrev, 1965)

Fig. 18 ; Table 3

Bernhardites nodosus Shevyrev, 1965: 171 , pl. 21 fig. 8.

Bernhardites nodosus – Shevyrev 1968: 87, pl. 2 fig. 2.

Shevyrevites nodosus – Korn et al. 2019: 46, text-fig. 13.

non Shevyrevites nodosus – Korn in Ghaderi et al. 2014: text-fig. 7d.

Diagnosis

Species of Shevyrevites with conch reaching 80 mm dm. Subadult stage with circular, slightly compressed whorl profile (ww/wh =0.60–0.75) and rounded venter; 10 coarse lateral nodes per volution. Adult stage with parallel-sided, slightly compressed whorl profile (ww/wh =0.60–0.75), flattened venter and subangular ventrolateral shoulder; radial plications. Prongs of external lobe simple or bifid; altogether about 15 notches of E, A and L lobes.

Type material

Holotype ARMENIA • Ogbin ; Late Permian; illustrated by Shevyrev (1965: pl. 24 fig. 1); PIN 1478/31 .

Material examined

IRAN • 1 specimen; Esfahan Province, Baghuk Mountain C section ; Hambast Formation; MB.C.29713 • 1 specimen; Esfahan Province, Baghuk Mountain E section ; Hambast Formation; MB.C.29714 • 1 specimen; Esfahan Province, Baghuk Mountain G section ; Hambast Formation; MB.C.29715 • 2 specimens; Esfahan Province, Baghuk Mountain ; Hambast Formation; MB.C.29716 to MB.C.29717 .

Description

Specimen MB.C.29713 has 53 mm diameter and shows the partly crushed phragmocone and less than half a volution of the terminal body chamber ( Fig. 18 ). The whorl profile of the body chamber is subtrapezoidal with weakly converging flanks, a subangular ventrolateral shoulder and a flattened venter. The sculpture of the phragmocone differs significantly from the body chamber; while the phragmocone bears coarse conical nodes (10 per volution) and later elongate sharp ribs on the midflank, the body chamber has weak and blunt radial ribs. Only portions of the suture line can be seen on the flank; they show a finely serrated adventive lobe.

Remarks

Shevyrevites nodous differs in the coarse lateral nodes of the subadult stage from S. shevyrevi and S. corrugatus sp. nov.

Stratigraphic range

Upper part of the Hambast Formation; 4.45 m below the extinction horizon ( Shevyrevites nodosus Zone ).

Figures

Fig. 18. Shevyrevites nodosus (Shevyrev, 1965), lateral and reconstructed dorsal view of specimen MB.C.29713. Scale bar units=1 mm.