New Finds of Triassic Marine Reptiles from Eastern Russia: Ammonoid Age Control and Possible Evidence for Ichthyopterygian Affinities

This paper presents a description of the Olenekian–Anisian sections in South Primorye, Far East Russia, containing reptile remains. The paper describes important ammonoid Flexoptychites cf. rifunus (Yabe et Shimizu), as well as Flexoptychites cf. compressus (Yabe et Shimizu), which are stratigraphically significant. New Anisian reptile remains were discovered from four stratigraphic levels in South Primorye: (1) the upper part of the middle Anisian Acrochordiceras kiparisovae Zone (Ichthyopterigia indet. A), (2) the middle part of the upper Anisian Flexoptychites cf. rifunus Beds (Reptilia indet. cf. Ichthyopterygia A), (3) the upper part of the upper Anisian Flexoptychites cf. rifunus Beds (Ichthyoterygia indet. B), and (4) the uppermost part of the upper Anisian Flexoptychites cf. rifunus Beds (Reptilia indet. cf. Ichthyopterygia B). The Anisian stage is marked by an abundance of medium- to large-sized ichthyopterygians and a comparatively limited number of gigantic forms, particularly in the eastern Panthalassic and western Tethyan provinces. Our recent discovery has unveiled the presence of medium- to large-sized reptiles, seemingly ichthyopterygians, in the western Panthalassic province during the late Anisian ( Flexoptychites cf. rifunus Chrone).