The Changhsingian (Late Permian) ammonoids from Baghuk Mountain (Central Iran) Author Korn, Dieter 286CA4F3-7EBC-4AEF-A66A-B2508D001367 Museum für Naturkunde, Leibniz Institut for Research on Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany. dieter.korn@mfn.berlin Author Hairapetian, Vachik 1AB10F8F-4576-481B-9270-5DCD25110DBB Department of Geology, Esfahan (Khorasgan) Branch, Islamic Azad University, Esfahan, Iran. vhairap@gmail.com Author Ghaderi, Abbas 925F2B42-7326-4461-B2A6-83CB83ECCC63 Department of Geology, Faculty of Science, Ferdowsi University of Mashhad, Azadi Square, 9177948974, Mashhad, Iran. aghaderi@um.ac.ir Author Leda, Lucyna 81481AFA-C8EE-4E90-A954-FD0E7987621E Museum für Naturkunde, Leibniz Institut for Research on Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany. lucyna.skorpion3@wp.pl Author Schobben, Martin 44C2A45A-B16C-434F-8F22-FC9C0FCA2551 Utrecht University, Department of Earth Sciences, Princetonlaan 8 A, 3584 CB Utrecht, The Netherlands. & Department of Geology, Esfahan (Khorasgan) Branch, Islamic Azad University, Esfahan, Iran. schobbenmartin@gmail.com Author Akbari, Amir 3C9DB6F9-2034-418F-876C-49359D07D29F Department of Geology, Esfahan (Khorasgan) Branch, Islamic Azad University, Esfahan, Iran amakbari80@yahoo.com text European Journal of Taxonomy 2021 2021-10-27 776 1 106 journal article 3782 10.5852/ejt.2021.776.1559 453c885c-f427-4a38-ab97-dc14b686e126 2118-9773 5604715 226B6C59-8620-4A29-9BEF-359BE67A1A2C Paratirolites trapezoidalis Shevyrev, 1965 Fig. 32 ; Table 15 Paratirolites trapezoidalis Shevyrev, 1965: 177 , pl. 24 fig. 1. Paratirolites trapezoidalis – Shevyrev 1968: 92 , pl. 4 fig. 1. — Korn in Ghaderi et al. 2014 : text-fig. 7e. — Korn & Ghaderi in Korn et al. 2016: 858 , text-fig. 16. Diagnosis Species of Paratirolites with conch reaching 120 mm dm. Subadult stage with trapezoidal, depressed whorl profile (ww/wh= 1.40–1.60) and flattened, slightly tectiform venter; 10–15 coarse ribs, which end in coarse conical ventrolateral nodes, per volution. Adult stage with strongly trapezoidal and weakly depressed whorl profile (ww/wh =1.00–1.40), flattened venter and angular ventrolateral shoulder; weak straight riblets and numerous small ventrolateral nodes. Prongs of external lobe usually unsubdivided, rarely trifid; altogether 12–19 notches of E, A and L lobes. Type material Holotype AZERBAIJAN • Nakhichevan Province , Dorasham 2 section ; Paratirolites Limestone ; illustrated by Shevyrev (1965 : pl. 24 fig. 1); PIN 1252/129 . Table 15. Conch dimensions (partly estimated) and ratios of selected specimens of Paratirolites trapezoidalis Shevyrev, 1965 from Baghuk Mountain.

Specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZR
MB.C.29845	79.0	30.6	28.1	30.5	26.0	0.39	1.09	0.39	2.22	0.07
MB.C.29844	71.0	26.4	25.3	29.3	23.7	0.37	1.04	0.41	2.25	0.06
MB.C.29846	88.9	–	28.5	39.3	27.2	–	–	0.44	2.08	0.05

Fig. 32. Paratirolites trapezoidalis Shevyrev, 1965 . A–B . Lateral and dorsal views. A . Specimen MB.C.29845, section E, -2.80 m. B . Specimen MB.C.29844, section E, float. C . Suture line of specimen MB.C.29844, at 13.3 mm wh. Abbreviation: see Material and methods. Scale bar units =1 mm. Material examined IRAN • 1 specimen ; Esfahan Province , Baghuk Mountain C section ; Hambast Formation ; MB.C.29843 • 2 specimens ; Esfahan Province , Baghuk Mountain E section ; Hambast Formation ; MB.C.29844 to MB.C.29845 • 3 specimens ; Esfahan Province , Baghuk Mountain ; Hambast Formation ; MB.C.29846 to MB.C.29848 . Description Specimen MB.C.29844 is a moderately well-preserved individual of 71 mm conch diameter and allows the study of one and a half whorls ( Fig. 32B ). The last segment of 210 degrees belongs to the body chamber, which has a weakly depressed trapezoidal whorl profile (ww/wh =1.05) with weakly concave flanks and a nearly flat venter and an angular ventrolateral shoulder. The sculpture of the subadult stage consists of conical and coarse, spiny ventrolateral nodes, 13 on the last phragmocone volution. The nodes become significantly weaker and more numerous on the body chamber, where about 16 of them are present on half a volution. Specimen MB.C.29844 allows only the study of the suture line on the venter. The external lobe is narrow and parallel-sided with non-serrated, narrow lanceolate prongs. The ventrolateral saddle is very asymmetric and dorsally inclined and the asymmetric adventive lobe has an oblique base that is serrated by six small notches ( Fig. 32C ). specimen MB.C.29845 ( Fig. 32A ) is similar in conch shape and sculpture but possesses a suture line with trifid prongs of the external lobe. Remarks Paratirolites vediensis has a similar conch shape, but differs from P. trapezoidalis in the stronger ventrolateral nodes in the adult stage. P. coronatus has an even wider whorl profile (ww/wh = 1.60–1.80 in P. coronatus but only 1.40 in P. trapezoidalis ); the species has also less coarse but more numerous ventrolateral nodes in the subadult stage ( 15 in P. coronatus but only 10 in P. trapezoidalis ). Stratigraphic range Upper part of the Hambast Formation; 3.05 to 2.80 m below the extinction horizon ( Paratirolites kittli Zone ).