Gastropod evidence against the Early Triassic Lilliput effect.

Arnaud Brayard (1) , Alexander Nützel (2) , Daniel A. Stephen (3) , Kevin G. Bylund , Jim Jenks , Hugo Bucher (4, 5)

1 BGS - Biogéosciences [UMR 6282]
2 Department für Geo- und Umweltwissenschaften, Sektion für Paläontologie
3 Department of Earth Science
4 Paläontologisches Institut und Museum
5 D-ERDW - Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich]

Size reduction in the aftermath of the Permian-Triassic mass extinction event has repeatedly been described for various marine organisms, including gastropods (the Lilliput effect). A Smithian gastropod assemblage from Utah, USA, reveals numerous large-sized specimens of different genera as high as 70 mm, the largest ever reported from the Early Triassic. Other gastropods reported from Serbia and Italy are also as large as 35 mm. Size frequency distributions of the studied assemblages indicate that they were not unusually small when compared with later Mesozoic and modern faunas. The occurrence of large-sized gastropods less than 2 Ma after the Permian-Triassic mass extinction refutes the Lilliput hypothesis in this clade, at least for the last ~75% of the Early Triassic.

Domaines: Paléontologie

Arnaud Brayard, Alexander Nützel, Daniel A. Stephen, Kevin G. Bylund, Jim Jenks, et al.. Gastropod evidence against the Early Triassic Lilliput effect.. Geology, 2010, 38 (2), pp.147-150. ⟨10.1130/G30553.1⟩. ⟨hal-00454137⟩