The Ravenscrag Butte flora: Paleoclimate and paleoecology of an early Paleocene (Danian) warm-temperate deciduous forest near the vanishing inland Cannonball Seaway

The Ravenscrag Butte flora in southwestern Saskatchewan, Canada, provides a record of an early Paleocene (Danian) forest ecosystem that followed the K-Pg boundary event. Plant macrofossil collections were investigated to assess the paleoclimate and paleoecology of the forest. An ensemble approach to climate analysis using leaf physiognomic and nearest living relative methods indicates that the forest grew under warm and wet temperate conditions, with mild frost-free winters, and did not experience a significant drying season—although some precipitation seasonality is indicated. Reconstructed leaf mass per area suggests that the woody broadleaf dicot flora had an entirely deciduous habit, despite temperature and precipitation conditions that were suitable for evergreen taxa. The reconstructed climate of the Ravenscrag Butte flora is similar to modern coastal climates with proximity to an inland sea (e.g., Croatia and Slovenia on the Adriatic Sea and Georgia on the Black Sea), suggesting that the Ravenscrag Butte flora was influenced by its proximity to the western margin of the early Paleocene Cannonball Seaway. The leaf physiognomy of the Ravenscrag Butte flora is most similar to contemporaneous fossil macrofloras from throughout western and northern North America, which suggests physiognomic homogeneity over broad latitudes during the early Paleocene, a potential consequence of vegetation reorganization after the K-Pg event.