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 (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Paläontologisches Institut und Museum, Universität Zürich Zürich = University of Zurich (UZH), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Department für Geo- und Umweltwissenschaften, Sektion für Paläontologie, Bayerische Staatssammlung für Paläontologie und Geologie-Ludwig Maximilian University Munich = Ludwig Maximilians Universität München (LMU), Laboratoire Magmas et Volcans (LMV), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS), Department of Earth Science, Utah Valley University (UVU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Gastropods; Biotic recovery; Body size; Early Triassic; Lilliput effect; Sampling effect; [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology; Greenland; Gulliver
• Online Access: https://hal.science/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.