Arctic mosasaurs (Squamata, Mosasauridae) from the Upper Cretaceous of Russia

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.…”

“…Tylosaurinae (and Mosasauridae in general) had a global distribution and are also known from very high latitudes, indicating an endothermic metabolism ( Grigoriev and Grabovskiy, 2020 ). Representatives of this subfamily are known from Turonian–Maastrichtian deposits of North America ( Everhart, 2005b ), South America ( Fernández and Gasparini, 2012 ; Otero, 2021 ), Europe ( Hornung and Reich, 2015 ; Romano et al, 2019 ), Africa ( Antunes, 1964 ; Rempert et al, 2022 ), Japan ( Caldwell et al, 2008 ), New Zealand ( Caldwell et al, 2005 ), and Antarctica ( Fernandez and Martin, 2009 ; Otero et al, 2017 ).…”

“…Representatives of this subfamily are known from Turonian–Maastrichtian deposits of North America ( Everhart, 2005b ), South America ( Fernández and Gasparini, 2012 ; Otero, 2021 ), Europe ( Hornung and Reich, 2015 ; Romano et al, 2019 ), Africa ( Antunes, 1964 ; Rempert et al, 2022 ), Japan ( Caldwell et al, 2008 ), New Zealand ( Caldwell et al, 2005 ), and Antarctica ( Fernandez and Martin, 2009 ; Otero et al, 2017 ). In Russia, tylosaurine remains were found in Campanian–Maastrichtian deposits of European Russia and the Russian Far East region ( Grigoriev, 2017 ; Grigoriev and Grabovskiy, 2020 ).…”