A temperate palaeodiversity peak in Mesozoic dinosaurs and evidence for Late Cretaceous geographical partitioning

Authors

  • Philip D. Mannion,

    Corresponding author
    1. Department of Earth Sciences, UCL, University College London, Gower Street, London WC1E 6BT, UK
    2. Museum für Naturkunde, Invalidenstrasse 43, 10115 Berlin, Germany
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  • Roger B. J. Benson,

    1. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
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  • Paul Upchurch,

    1. Department of Earth Sciences, UCL, University College London, Gower Street, London WC1E 6BT, UK
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  • Richard J. Butler,

    1. Geo-Bio Center, Ludwig-Maximilians-Universität Munich, Richard-Wagner-Straße 10, 80333 Munich, Germany
    2. Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Straße 10, 80333 Munich, Germany
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  • Matthew T. Carrano,

    1. Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012, USA
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  • Paul M. Barrett

    1. Department of Palaeontology, Natural History Museum, Cromwell Road, London SW7 5BD, UK
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Philip D. Mannion, Museum für Naturkunde, Invalidenstrasse 43, 10115 Berlin, Germany. E-mail: philipdmannion@gmail.com

ABSTRACT

Aim  Modern biodiversity peaks in the tropics and declines poleward, a pattern that is potentially driven by climate. Although this latitudinal biodiversity gradient (LBG) also characterizes the marine invertebrate fossil record, distributions of ancient terrestrial faunas are poorly understood. This study utilizes data on the dinosaur fossil record to examine spatial patterns in terrestrial biodiversity throughout the Mesozoic.

Location  We compiled data on fossil occurrences across the globe.

Methods  We compiled a comprehensive dataset of Mesozoic dinosaur genera (738), including birds. Following the utilization of sampling standardization techniques to mediate for the uneven sampling of the fossil record, we constructed latitudinal patterns of biodiversity from this dataset.

Results  The dominant group of Mesozoic terrestrial vertebrates did not conform to the modern LBG. Instead, dinosaur diversity was highest at temperate palaeolatitudes throughout the 160 million year span of dinosaurian evolutionary history. Latitudinal diversity correlates strongly with the distribution of land area. Late Cretaceous sauropods and ornithischians exhibit disparate LBGs.

Main conclusions  The continuity of the palaeotemperate peak in dinosaur diversity indicates a diminished role for climate on the Mesozoic LBG; instead, dinosaur diversity may have been driven by the amount of land area among latitudinal belts. There is no evidence that the tropics acted as a cradle for dinosaur diversity. Geographical partitioning among major clades of herbivorous dinosaurs in the Late Cretaceous may result from the advanced stages of continental fragmentation and/or differing responses to increasing latitudinal climatic zonation. Our results suggest that the modern-day LBG on land was only established 30 million years ago, following a significant post-Eocene recalibration, potentially related to increased seasonality.

Ancillary