title: Extinction of fish-shaped marine reptiles associated with reduced evolutionary rates and global environmental volatility.
abstract: Despite their profound adaptations to the aquatic realm and their apparent success throughout the Triassic and the Jurassic, ichthyosaurs became extinct roughly 30 million years before the end-Cretaceous mass extinction. Current hypotheses for this early demise involve relatively minor biotic events, but are at odds with recent understanding of the ichthyosaur fossil record. Here, we show that ichthyosaurs maintained high but diminishing richness and disparity throughout the Early Cretaceous. The last ichthyosaurs are characterized by reduced rates of origination and phenotypic evolution and their elevated extinction rates correlate with increased environmental volatility. In addition, we find that ichthyosaurs suffered from a profound Early Cenomanian extinction that reduced their ecological diversity, likely contributing to their final extinction at the end of the Cenomanian. Our results support a growing body of evidence revealing that global environmental change resulted in a major, temporally staggered turnover event that profoundly reorganized marine ecosystems during the Cenomanian.
authors.affiliation: Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN Oxford, UK.|Department of Geology, University of Liège, 14 Allée du 6 Août, 4000 Liège, Belgium.
authors.forename: Valentin
authors.initials: V
authors.lastname: Fischer
authors.affiliation: Département Histoire de la Terre, Muséum National d'Histoire Naturelle, Sorbonne Universités, CR2P CNRS-MNHN-UPMC Paris 6, CP 38, 8 rue Buffon, 75005 Paris, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bardet
authors.affiliation: Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN Oxford, UK.
authors.forename: Roger B J
authors.initials: RB
authors.lastname: Benson
authors.affiliation: Faculty of Ecology, Saratov State Technical University, Politekhnicheskaya St 77, 410054 Saratov, Russia.|Faculty of Ecology, Saratov State University, Astrakhanskaya St 83, 410012 Saratov, Russia.
authors.forename: Maxim S
authors.initials: MS
authors.lastname: Arkhangelsky
authors.affiliation: Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN Oxford, UK.
authors.forename: Matt
authors.initials: M
authors.lastname: Friedman
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000145:classification / Q000235:genetics*; D044822:Biodiversity; D005075:Biological Evolution; D017753:Ecosystem; D005580:Fossils; D010802:Phylogeny; D012104:Reptiles / Q000145:classification / Q000235:genetics*