Diversity of the anatomically preserved Tournaisian flora of Argentina.

PRESTIANNI, CYRILLE; BALSEIRO, DIEGO; VACCARI, NORBERTO EMILIO; RUSTÁN, JUAN JOSÉ; SFERCO, MARTA EMILIA; EZPELETA, MIGUEL

Congreso; Agora Paleobotanica Meeting; 2023

The transition from the Devonian to the Carboniferous is marked by important environmental changes that led to a major biodiversity crisis in the marine realm (Kaiser et al. 2016). The effects of this event on the continental ecosystems seems to have regularly been overestimated in the past. The timing of the event on continents are still poorly constrained, but data on plants (Cascales-Miñana and Cleal, 2014; Decombeix et al., 2011; Prestianni et al., 2015) tend to show that the continental ecosystems were more resilient, even if undoubtedly affected by the crisis. In this presentation, we will document a new Tournaisian plant locality within the Argentinian precordillera that will help us address these questions. The here discussed sequence was discovered in the course of an ongoing effort to investigate the Sierra de las Minitas (La Rioja Province, Argentina), a small mountain range of fossiliferous rocks exposing sediment from the Lower Devonian to the Late Tournaisian (Prestianni et al. 2015 and 2022; Ezpeleta et al. 2020; Sterren et al. 2021). This locality yields abundant plant and animal fossils including many phosphatic nodules presenting anatomically preserved plant remains. The plant assemblage is relatively diverse. It is dominated by four species of both arborescent and herbaceous Cladoxylopsida and by three species of Lycopsida. Other plants are comprised of Filicophyta and Spermatopsida. This flora presents clear transitional traits between the Devonian and the Carboniferous and remains diverse despite its position after the Devonian Carboniferous transition. This provides further evidence for a clear decoupling between the extinction dynamics in the marine and continental realms.