La réanalyse de fossiles au Brésil remet en cause les origines des premiers animaux

12 mai 2026

Rapporté par l'IA

Des scientifiques ont déterminé que des structures autrefois considérées comme des traces de minuscules animaux dans des roches brésiliennes vieilles de 540 millions d'années sont en réalité des communautés fossilisées de bactéries et d'algues. Ce réexamen utilise une imagerie avancée pour révéler des cellules et des matières organiques préservées.

Les chercheurs se sont concentrés sur des microfossiles provenant de la formation de Tamengo, dans le Mato Grosso do Sul. Des travaux antérieurs avaient interprété ces marques comme la preuve de créatures vermiformes se déplaçant dans les sédiments marins durant la période de l'Édiacarien, juste avant l'explosion cambrienne de la vie complexe. Une nouvelle analyse par microtomographie et spectroscopie Raman à l'accélérateur de particules Sirius a mis en évidence des structures cellulaires plutôt que des traces animales.

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mardi 12 mai 2026 04h54