High Diversity in Cretaceous Ichthyosaurs from Europe Prior to Their Extinction

摘要: Background Ichthyosaurs are reptiles that inhabited the marine realm during most of Mesozoic. Their Cretaceous representatives have traditionally been considered as last survivors a group declining since Jurassic. Recently, however, an unexpected diversity has described in Upper Jurassic–Lower deposits, but is widely spread across time and space, giving small clues on adaptive potential ecosystem control ichthyosaurs. The famous little studied English Gault Formation ‘greensands’ deposits (the Greensand Cambridge Member Lower Chalk Formation) offer unprecedented opportunity to investigate this topic, containing thousands ichthyosaur remains spanning Early–Late boundary. Methodology/Principal Findings To assess assemblage from these sedimentary bodies, we recognized morphotypes within each type bones. We grouped together, when possible, by using articulated specimens same formations new localities Vocontian Basin (France); revised taxonomic scheme proposed. recognize following taxa ‘greensands’: platypterygiines ‘Platypterygius’ sp. Sisteronia seeleyi gen. et nov., indeterminate ophthalmosaurines rare incertae sedis Cetarthrosaurus walkeri. late Albian ichthyosaurs now matches older, well-known intervals such Toarcian or Tithonian. Contrasting tooth shapes wear patterns suggest colonized three distinct feeding guilds, despite presence numerous plesiosaur taxa. Conclusion/Significance Western Europe was hot-spot for few million years prior their final extinction. By contrast, low Australia U.S.A. suggests strong geographical disparities pattern Albian–early Cenomanian This provides whole context extinction successful reptiles, at end Cenomanian.