Early Triassic Gulliver gastropods: Spatio-temporal distribution and significance for biotic recovery after the end-Permian mass extinction

• Published in: Earth-Science Reviews
• Main Authors: Brayard, Arnaud, Meier, Maximiliano, Escarguel, Gilles, Fara, Emmanuel, Nützel, Alexander, Olivier, Nicolas, Bylund, Kevin G., Jenks, James F., Stephen, Daniel A., Hautmann, Michael, Vennin, Emmanuelle, Bucher, Hugo
• Other Authors: Biogéosciences UMR 6282 Dijon (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), Paläontologisches Institut und Museum, Universität Zürich Zürich (UZH), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement Lyon (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Department für Geo- und Umweltwissenschaften, Sektion für Paläontologie, Ludwig-Maximilians-Universität München (LMU)-Bayerische Staatssammlung für Paläontologie und Geologie, Laboratoire Magmas et Volcans (LMV), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Université Jean Monnet Saint-Étienne (UJM), Department of Earth Science, Utah Valley University (UVU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Gastropods; Lilliput effect; Early Triassic; Body size; Biotic recovery; Sampling effect; [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology; Greenland; Gulliver
• Online Access: https://hal.archives-ouvertes.fr/hal-01141883; https://doi.org/10.1016/j.earscirev.2015.03.005

International audience A reduction in body size (Lilliput effect) has been repeatedly proposed for many marine organisms in the aftermath of the Permian–Triassic (PT) mass extinction. Specifically-reduced maximum sizes of benthic marine invertebrates have been proposed for the entire Early Triassic. This concept was originally based on observations on Early Triassic gastropods from the western USA basin and the Dolomites (N Italy) and it stimulated subsequent studies on other taxonomic groups. However, only a few studies have tested the validity of the Lilliput effect in gastropods to determine whether the paucity of large-sized gastropods is a genuine signal or the result of a poor fossil record and insufficient sampling. In combination with a review of the literature, we document numerous new, abundant, large-sized gastropods from the Griesbachian outcrops of Greenland and from the Smithian–early Spathian interval in the southwestern USA. We show that large-sized (“Gulliver”) gastropods (i) were present soon after the PT mass extinction, (ii) occurred in various basins, sedimentary facies and environmental contexts (from shallow to deeper settings), and (iii) belong to diverse higher-rank taxa. Focusing on the western USA basin, we investigate areas from which microgastropod shell-beds were previously presented as being typical. However, we show that Gulliver gastropods do occur in the very same areas. Insufficient sampling effort is probably the main reason for the rarity of reports of large Early Triassic gastropods, which is supported by preliminary rarefaction-based simulations. Finally, it appears that the recently documented middle to late Smithian climate shifts and the severe end-Smithian extinction of nekto-pelagic faunas did not reduce maximum shell sizes of gastropods.