Dinoturbation in the Cretaceous Areado Group, Sanfranciscana Basin (Brazil)

Resumo

Soft-sediment deformation structures (SSDS) can be produced by abiotic factors, invertebrate bioturbation, or trampling by large tetrapods. Differentiating between these origins is crucial for ichnological interpretation, particularly in stratigraphic units where body fossils are rare or bedding-plane exposures are limited. In this study, we describe new occurrences of SSDS interpreted as dinoturbations—cross-sectional tracks formed by heavy tetrapods—in the Três Barras Formation (Areado Group, Abaeté Sub-Basin, Sanfranciscana Basin), in Minas Gerais State, Brazil. These structures occur in fine- to medium-grained, cross-bedded sandstones, and preserve downward deformation, faulting, and local compaction. Their features, along with their stratigraphic position, support interpretation as tetrapod trampling traces, possibly produced by dinosaurs. These ichnological findings are significant within the context of the marine incursions into the Sanfranciscana Basin, as the dinoturbations indicate that, at the time of their formation, the environment was continental. This highlights the potential of ichnological data to refine paleoenvironmental reconstructions and to identify stratigraphic intervals in which the depositional system was predominantly continental during episodic marine incursions in intracratonic basins.

 Keywords: soft-sediment deformation structures (SSDS), Três Barras Formation, tetrapod ichnology, continental, eolian.