The ecology of modern and fossil vertebrates revisited by lithium isotopes

Fanny Thibon (1, 2) , Jean Goedert (3) , Nicolas Séon (3) , Lucas Weppe (2, 4) , Jeremy E Martin (1) , Romain Amiot (1) , Sylvain Adnet (5) , Olivier Lambert (6) , Paco Bustamante (4, 7) , Christophe Lécuyer (1) , Nathalie Vigier (2)

1 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
2 LOV - Laboratoire d'océanographie de Villefranche
3 CR2P - Centre de Recherche en Paléontologie - Paris
4 LIENSs - LIttoral ENvironnement et Sociétés
5 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier
6 IRSNB - Institut Royal des Sciences Naturelles de Belgique
7 IUF - Institut universitaire de France

The vertebrate fossil record documents a plethora of transitions between aquatic and terrestrial environments but their causes are still debated. Quantifying the salinity of living environments is therefore crucial for precising the sequence of ecological transitions. Here, we measured lithium stable isotope composition of mineralized tissues (δ 7 Limt) of extant and extinct vertebrates from various aquatic environments: seawater, freshwater/terrestrial, and "transitional environments" (i.e. brackish waters, or seasonal access to freshwater and seawater). We report statistically higher δ 7 Limt values for seawater vertebrates than freshwater ones, taxonomic groups considered separately. Moreover, vertebrates living in transitional environments have intermediate δ 7 Limt values. Therefore, we show that δ 7 Limt values of both extant and extinct vertebrates can discriminate their aquatic habitat.

Mots clés: Lithium isotopes; Mineralized tissues; Aquatic environments; Paleoecology

Domaines: Paléontologie; Biodiversité et Ecologie; Géochimie

Fanny Thibon, Jean Goedert, Nicolas Séon, Lucas Weppe, Jeremy E Martin, et al.. The ecology of modern and fossil vertebrates revisited by lithium isotopes. Earth and Planetary Science Letters, 2022, 599, pp.117840. ⟨10.1016/j.epsl.2022.117840⟩. ⟨hal-03819112⟩