Many dicotyledonous plants employ folding of immature leaf surfaces into buds before developing into mature leaves. Bud folding in leaves is impacted by taxonomy and ecology, and fossil evidence provides insight into its evolution. Direct evidence of leaf-bud folding patterns is rare in the fossil record. Herein, we describe leaf compressions from the middle Eocene (47.8–37.71 Ma) Geiseltal lignite deposits in Germany, which exhibit feeding damage consisting of files of holes across the leaf (damage types DT06 and DT425). We compare the damage on these leaves to various models of bud-feeding, including digital and paper origami, and artificial damage to living leaf buds, to more accurately interpret the fossils. One of the specimens exhibits a complex damage pattern, which can be roughly assigned to seven lines of holes across the leaf. Models based on this fossil leaf indicate that the pattern of damage is consistent with an insect feeding on a leaf bud that was folded in a semi-corrugated pattern, creating the observed damage after bud burst (DT06). The two other fossil leaves exhibit a simpler pattern of bilaterally symmetrical damage. This likely resulted from an insect feeding on these leaves while they were folded in half, as a bilaterally folded bud, or a mature leaf folded in half at night or in response to herbivory (DT425). The patterns observed in these fossil leaves may confirm ecologies and life histories that are not otherwise directly recorded. Moreover, the models presented here contribute to recognizing bud-feeding traces in the fossil record.

Caldera lake sediments of the early Eocene Tufolitas Laguna del Hunco (Chubut Province, Argentina) host one of the world's best-preserved and most diverse fossil plant assemblages, but the exceptional quality of preservation remains unexplained. The fossils have singular importance because they include numerous oldest and unique occurrences in South America of genera that today are restricted to the West Pacific region, where many of them are now vulnerable to extinction. Lacustrine depositional settings are often considered optimal for preservation as passive receptors of suspended sediment delivered, often seasonally, from lakeshores. However, caldera lakes can be influenced by a broader range of physical and chemical processes that enhance or decrease fossil preservation potential. Here, we use Laguna del Hunco to provide a new perspective on paleoenvironmental controls on plant fossil preservation in tectonically active settings. We establish a refined geochronological framework for the Laguna del Hunco deposits and present a detailed history of processes active during ∼ 200,000 years of lake filling from 52.217 ± 0.014 Ma to 51.988 ± 0.035 Ma, the time interval that encompasses nearly all fossil deposition. Detailed facies analysis shows that productive fossil localities reside within high-deposition-rate beds associated with high-energy density flows and wave-reworked lake-floor sediments, challenging traditional views that low-energy environments are required for well-preserved plant fossils. These results demonstrate that even delicate fossil components like fruits and flowers can survive high-energy transport, underscoring the importance of rapid burial as a primary control on fossil preservation. Short, steep sediment-transport networks may facilitate terrestrial fossil preservation by limiting opportunities for biochemical degradation on land and providing relatively frequent, high-energy depositional events, which quickly transport and bury organic material following events such as landslides from steep, wet, surrounding slopes. Our new model for plant taphonomy opens a path toward finding and understanding other exceptional biotas in environments once considered unlikely for preservation.