Northernmost occurrences of plesiosaurs and turtles in the Upper Cretaceous of Eurasia

Fossil marine vertebrates (Chondrichthyes, Actinopterygii, Reptilia) from the Upper Cretaceous of Akkermanovka (Orenburg Oblast, Southern Urals, Russia)

“…Marine reptiles are not very abundant in Akkermanovka and are only represented by two families, Mosasauridae (Squamata) and Polycotylidae (Plesiosauria). Remains of marine reptiles have been commonly reported from the Mesozoic epicontinental marine deposits of western and eastern Russia but are usually poorly preserved and taxa were left in open nomenclature ( Storrs et al, 2000 ; Arkhangelsky et al, 2007 ; Grigoriev and Grabovskiy, 2020 ; Zverkov et al, 2023a ). In the Akkermanovka assemblage, marine reptiles are only represented by teeth and do not allow identification beyond family or subfamily levels.…”

“…In the Akkermanovka assemblage, marine reptiles are only represented by teeth and do not allow identification beyond family or subfamily levels. Whereas polycotylids are well known from Orenburg ( Bogolyubov, 1912b ; Efimov et al, 2016 ) and Russia in general ( Pervushov et al, 1999 ; Storrs et al, 2000 ; Arkhangelsky et al, 2007 ; Zverkov et al, 2023a ), tylosaurines (Mosasauridae) have rarely been reported to date ( Bogolyubov, 1910 ; Grigoriev and Grabovskiy, 2020 ). The marine reptiles of the Akkermanovka assemblage therefore further contributes to our knowledge of the spatio-temporal distribution of these taxa in Russia.…”

“…The remains of members of the family have been found in the Aptian–Maastrichtian of North America ( O'Keefe, 2004 ; Schumacher and Martin, 2016 ), South America ( O’Gorman and Gasparini, 2013 ), Europe ( Persson, 1959 ), North Africa ( Bardet et al, 2003 ; Allemand et al, 2018 ), Japan ( Sato and Storrs, 2000 ), New Zealand ( O’Gorman and Otero, 2023 ), Australia ( Kear, 2005 ), and Antarctica ( Novas et al, 2015 ). In Russia, polycotyloid remains have been found in Albian–Campanian deposits in European Russia and Eastern Siberia ( Pervushov et al, 1999 ; Storrs et al, 2000 ; Arkhangelsky et al, 2007 ; Zverkov et al, 2023a ).…”

A plesiosaurian autopodial element (Plesiosauria indet.) with remarkable articular subchondral surfaces from the Maastrichtian type area (south-east Netherlands)

“…Members of the family Elasmosauridae were still widespread and diverse during the latest Maastrichtian, as exemplified by Zarafasaura from phosphatic strata of Morocco (Lomax & Wahl, 2013; Vincent et al, 2013), as well as by material from Chile (Otero et al, 2014), Argentina (O’Gorman et al, 2014), Antarctica (O’Gorman & Coria, 2016) and Arctic regions of Eurasia (Zverkov et al, 2023) and North-America (Russell, 1967). Until recently, only two polycotylid clades appeared to have ranged into the early Maastrichtian, namely Occultonectia and Polycotylinae (Mulder et al, 2000; Sato, 2005; O’Gorman & Gasparini, 2013; Fischer et al, 2018).…”