The Upper Famennian Ketleri Formation of Latvia: new data on the fauna and flora from tide-dominated delta deposits in a seasonal climate

Combined sedimentological and palaeontological studies of the vertebrate fossil-bearing deposits of the Upper Devonian, Upper Famennian Ketleri Formation have provided new data on the sedimentary environment of the deposits, as well as on taxonomic and taphonomic peculiarities of the fossil assemblage. Data from numerical modelling of the Baltic Devonian Basin demonstrate that the sandy deposits of the Pavāri and Varkaļi members form a fan-shaped area resembling a wide delta developed in shallow-marine settings. Fluvial channels and bars with strong tidal influence were identified in a sedimentological study of the Pavāri site, suggesting a tide-influenced fluvial environment. Taphonomic studies indicate that the sedimentary concentrations of well-preserved vertebrate remains were formed under the influence of fluvial and strong tidal processes in a shallow-water environment, most likely in tide-influenced deltaic settings. Trace fossils recognised in the Ketleri and Pavāri-1 sites suggest a brackish-water or marine environment, and thus support the hypothesis. The analysis of rhizocretes from the Varkaļi Member suggests the strong influence of a seasonal climate. Well-preserved plant macroremains have been discovered for the first time during this study in the Ketleri Formation.