A new species of ammonoids from the Upper Jurassic of the Pechora River basin

The authors studied the Upper Jurassic — Lower Cretaceous deposits of  the Paromes Formation in the Pechora River basin found in the Izhma and Kedva rivers outcrops (Komi Republic). These works contributed to clarifying the Mesozoic block of the Mezen series sheets legend of the State Geological Map (scale of 1 : 1,000,000). Field work aided in collecting a diverse collection of macrofauna, with bivalves dominating, as well as fewer ammonoids and belemnites included. Exploring the gathered macrofauna led to find and describe a new species of ammonoids Epivirgatites mesezhnikovi sp. nov., which is characteristic of the Epivirgatites nikitini zone in the Volgian Regional Stage. The new species of ammonoids accompanied rich assemblages of bivalves Buchia fischeriana (d’Orbigny), B. russiensis (Pavlow), B. mosquensis (Buch), B. spp., Pinna sp. indet., Liostrea sp. indet., and belemnites Cylindroteuthis (Cylindroteuthis) ex  gr. lepida Sachs et Nalnjaeva, Lagonibelus (Holcobeloides) volgensis (d’Orbigny), Lagonibelus sp. The work resulted in collecting an extensive collection of macrofauna, which updated the complex paleontological characteristics of the Paromes Formation and especially the Epivirgatites nikitini zone of the Volgian Regional Stage.

1. Kravets V. S., Mesezhnikov M. S., Slonimsky G. A. The structure of the Jurassic — Lower Cretaceous strata in the Pechora River basin. Biostratigraphy of the Mesozoic Deposits in Oil and Gas Regions of the USSR: VNIGRI Proc. / Sci. Ed. M. S. Mesezhnikov, A. I. Kirichkova. Vol. 388. Leningrad: VNIGRI; 1976. P. 27–41. (In Russ.).

2. Unified stratigraphic scheme of the Jurassic deposits of the Russian Platform. Explanatory note. St. Petersburg: VNIGRI; 1993. 72 p. (In Russ.).

3. Unified regional stratigraphic scheme of the Jurassic of East European Platform. Explanatory note / Comp. V. V. Mitta [et al.]; Eds. V. V. Mitta, A. S. Alekseev, S. M. Shik. Moscow: PIN RAS — VNIGNI; 2012. 63 p. (In Russ.).

4. Atlas of the mollusks of the Pechora Jurassic: Bulletin of VNIGRI no. 3 / Yu. S. Repin [et al.]; Sci. Ed. A. I. Kirichkova. St. Petersburg: Nedra; 2006. 261 p. (In Russ.).

5. The Kimmeridgian and Volgian stages of the north of the USSR. Leningrad: Nedra; 1984. 224 p. (In Russ.).

6. Nikitin S. Jurassic formations between Rybinsk, Mologa, and Myshkin. Materials for Geology of Russia: Imp. St. Petersburg Miner. Soc. Ed. Vol. X. St. Petersburg: Imp. Acad. of Sci. Print. House; 1881. P. 201–331. (In Russ.).

7. Stratigraphy of the Jurassic system of the North of the USSR / Publ. Ed. V. N. Saks. Moscow: Nauka; 1976. 436 p. (In Russ.).

8. Ivanov А. N., Muravin Е. S. Stratigraphy of the Middle Volga deposits near the village of Glebovo, Yaroslavl region. Jurassic Deposits of the Russian Platform: Proc. / Publ. Ed. M. S. Mesezhnikov. Leningrad: VNIGRI; 1986. P. 62–71. (In Russ.).

9. Rogov M. A. Ammonites and infrazonal stratigraphy of the Kimmeridgian and Volgian stages of Panboreal Superrealm: Trans. of the Geol. Inst. / Publ. Ed. V. A. Zakharov. Moscow: GIN RAS; 2021. 732 p. (In Russ.).