title: Climate constrains the evolutionary history and biodiversity of crocodylians.
abstract: The fossil record of crocodylians and their relatives (pseudosuchians) reveals a rich evolutionary history, prompting questions about causes of long-term decline to their present-day low biodiversity. We analyse climatic drivers of subsampled pseudosuchian biodiversity over their 250 million year history, using a comprehensive new data set. Biodiversity and environmental changes correlate strongly, with long-term decline of terrestrial taxa driven by decreasing temperatures in northern temperate regions, and biodiversity decreases at lower latitudes matching patterns of increasing aridification. However, there is no relationship between temperature and biodiversity for marine pseudosuchians, with sea-level change and post-extinction opportunism demonstrated to be more important drivers. A 'modern-type' latitudinal biodiversity gradient might have existed throughout pseudosuchian history, and range expansion towards the poles occurred during warm intervals. Although their fossil record suggests that current global warming might promote long-term increases in crocodylian biodiversity and geographic range, the 'balancing forces' of anthropogenic environmental degradation complicate future predictions.
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Mannion
authors.affiliation: Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK.
authors.forename: Roger B J
authors.initials: RBJ
authors.lastname: Benson
authors.affiliation: Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington DC 20013-7012, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Carrano
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Tennant
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK.
authors.forename: Jack
authors.initials: J
authors.lastname: Judd
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Butler
mesh_terms: D000489:Alligators and Crocodiles; D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D002980:Climate; D057231:Climate Change; D005580:Fossils; D013696:Temperature