(Ammonoidea: Stephanoceratidae) in the Upper Bajocian of the Northern Caucasus, Russia

Home , Stephanoceratidae, Stephanoceratoidea, Subcollina

N. Jb. Geol. Paläont. Abh. 288/3 (2018), 251–254 Article Stuttgart, June 2018

First record of Patrulia (Ammonoidea: Stephanoceratidae) in the Upper Bajocian of the Northern Caucasus, Russia

Vasily V. Mitta and Mikhail P. Sherstyukov With 3 ﬁgures

Abstract: Ammonites of the genus Patrulia STURANI, 1971, represented by the type species P. aenig- matica STURANI, are known from a few specimens from the base of the Upper Bajocian of Italy and France. A new species, P. karachaica MITTA, the youngest representative of the genus Patrulia, is described herein based on a single specimen from the lower part of the Parkinsoni Zone of the basin of the Kuban River (Karachay-Cherkessia).

Key words: Ammonites, Middle Jurassic, Upper Bajocian, Patrulia, Northern Caucasus.

1. Introduction This short note presents new data on the occurrence of Frebolditinae in the Upper Bajocian of the Northern The monotypic genus Patrulia STURANI, 1971 is known Caucasus. only from a few specimens from Western Europe from the basal horizons of the Strenoceras niortense Zone of the Upper Bajocian standard scale. Along with 2. Material Freboldites, Parabigotites, Bajocia, Subcollina, and Parastrenoceras, this genus is included in the subfam- In the last few years, the present authors studied the Mid- ily Frebolditinae (family Stephanoceratidae, superfam- dle Jurassic deposits of the basin of the Kuban River (e.g., MITTA & SHERSTYUKOV 2014), mainly in the Zelenchuk and ily Stephanoceratoidea), which registers a very limited Ust-Dzheguta districts of Karachay-Cherkessia. During ex- stratigraphic range, across the middle part of the Bajo- cavations in autumn 2017, one of us (MSH) found a single cian Stage (FERNÁNDEZ-LÓPEZ & PAV I A 2015). specimen of Patrulia in the outcrop no. 4 on the right bank Despite a wide geographical range, from the west- of the Kyafar River (left tributary of the Bolshoi Zelenchuk ern Tethys to the eastern Pacific, many taxa of this sub- River) (Fig. 1). family are known only from a few specimens and/or This section concerns the middle part of the Djangura Formation, composed of dark grey argillites with interbeds incomplete specimens, which do not give a full impres- of argillaceous limestone and numerous scattered sideritic sion of the intraspecific variability, dimorphism and nodules often concentrated along definite horizons (Fig. 2). evolution of the entire group. The relevance of the study The section deals with the lower part of the Parkinsonia par- of the subfamily Frebolditinae is further increased by kinsoni Zone (Rarecostites subarietis Subzone, Rarecostites the recent information that these stephanoceratids gave sherstyukovi faunal horizon). Apart from rare, mainly tran- sitional representatives of Lytoceratina and Phylloceratina, rise to the homeomorphic ammonites of the Spirocera- the section contains an oligotaxonic assemblage consisting tidae within the superfamily Spiroceratoidea (STURANI of Rarecostites (our collection from this locality includes 1971; SANDOVAL & WESTERMANN 1986; MITTA 2017a). several hundred specimens). In addition, this interval con-