Paratirolites kittli Stoyanow, 1910

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 : 44-46

Paratirolites kittli Stoyanow, 1910

Fig. 30 ; Table 13

Paratirolites Kittli Stoyanow, 1910: 82 , pl. 9 figs 1–2.

Stephanites ? Waageni Stoyanow, 1910: 89, pl. 8 fig. 3.

Pseudotirolites azariani Rostovtsev in Kotlyar et al., 1983: 154, pl. 15 fig. 5.

? Stephanites sp. indet. Stoyanow, 1910: 89, pl. 7 fig. 8.

Paratirolites kittli – Spath 1934: 366, text-fig. 125a–d. — Voinova et al. 1947: 169, pl. 40 fig. 4, textfig. 67. — Kummel 1957: 179, text-fig. 1a–b. — Shevyrev 1965: 174, pl. 22 fig. 4; 1968: 90, pl. 3 fig. 1. — Korn & Ghaderi in Korn et al. 2016: 862, text-figs 20–22.

Paratirolites waageni – Spath 1934: 367. — Shevyrev 1965: 175, pl. 22 figs 5–6; 1968: 90, pl. 2 figs 6–7.

Stephanites? waageni – Voinova et al. 1947: 167, pl. 40 fig. 3.

Diagnosis

Species of Paratirolites with conch reaching 190 mm dm. Subadult stage with rounded trapezoidal, weakly to moderately depressed whorl profile (ww/wh =1.30–1.60) and rounded venter; 10–12 very coarse ventrolateral nodes per volution. Adult stage with strongly trapezoidal and weakly depressed whorl profile (ww/wh =1.00–1.30), flattened tectiform venter and subangular ventrolateral shoulder; weak ventrolateral nodes. Prongs of external lobe usually multiply serrated; altogether 12–21 notches of E, A and L lobes.

Material examined

IRAN • 6 specimens; Esfahan Province, Baghuk Mountain 1 section ; Hambast Formation; MB.C.29813 to MB.C.29818 • 1 specimen; Esfahan Province, Baghuk Mountain A section ; Hambast Formation; MB.C.29819 • 1 specimen; Esfahan Province, Baghuk Mountain B section ; Hambast Formation; MB.C.29820 • 5 specimens; Esfahan Province, Baghuk Mountain C section ; Hambast Formation; MB.C.29821 to MB.C.29825 • 3 specimens; Esfahan Province, Baghuk Mountain E section ; Hambast Formation; MB.C.29826 to MB.C.29828 • 1 specimen; Esfahan Province, Baghuk Mountain F section ; Hambast Formation; MB.C.29829 • 6 specimens; Esfahan Province, Baghuk Mountain G section ; Hambast Formation; MB.C.29830 to MB.C.29835 • 2 specimens; Esfahan Province, Baghuk Mountain H section ; Hambast Formation; MB.C.29836 to MB.C.29837 • 4 specimens; Esfahan Province, Baghuk Mountain ; Hambast Formation; MB.C.29838 to MB.C.29841 .

Description

The large specimen MB.C.29833 (107 mm dm; Fig. 30A ) shows septal crowding at a phragmocone diameter of 70 mm, which indicates that the maximum conch diameter of this specimen was about 130 mm. The body chamber of the specimen is corroded but shows that the shape of the whorl profile is trapezoidal in the subadult and adult stage. The venter becomes nearly flat with an angular ventrolateral shoulder during formation of the terminal body chamber but is broadly rounded in the phragmocone. This specimen shows a sculpture of the phragmocone that consist of 12 coarse conical nodes on the outer flanks. These nodes become continuously weaker on the terminal body chamber.

The suture line of specimen MB.C.29833 has an external lobe with weakly diverging flanks, nearly parallel-sided prongs with three small notches. The ventrolateral saddle is narrow and dorsally inclined; it continues into the strongly asymmetric adventive lobe, which is asymmetrically serrated with numerous small notches climbing high up the ventral flank. By contrast, the lateral lobe is trifid and nearly symmetric ( Fig. 30B ).

Remarks

Paratirolites kittli differs from the otherwise similar P. vediensis in the more rounded whorl profile of the subadult stage, which in the latter is trapezoidal with a flattened venter and flattened diverging flanks.

Stratigraphic range

Upper part of the Hambast Formation; 3.10 to 2.40 m below the extinction horizon ( Paratirolites kittli Zone ).

Figures

Fig. 30. Paratirolites kittli Stoyanow, 1910. A. Lateral and dorsal view, specimen MB.C.29833, section G, -2.75 m. B. Suture line, specimen MB.C.29833, at 30 mm ww, 16.0 mm wh. Abbreviations: see Material and methods. Scale bar units =1 mm.