Early Evolution of Basal Angiosperms: Insights From the Fossil Pollen and Phylogenetics of Myristicaceae

Aim The early evolution of basal angiosperms and the diversification of flowering plants remain unclear due to fragmentary fossil records and unresolved deep phylogenetic relationships. This study focuses on Myristicaceae, an early diverging lineage of flowering plants, to clarify its evolutionary history and broader implications on determining the timing and drivers of basal angiosperm diversification. Location Tropics. Taxon Myristicaceae. Methods We integrated pollen morphology of Myristicaceae fossils from the Maastrichtian of Africa as well as India and early Paleogene of India, and extant species along with molecular sequences of 127 living species to reconstruct a dated phylogeny of Myristicaceae using BEAST2. To assess paleobiogeographic patterns, we applied BIOGEOBEARS in R, and diversification trends were assessed using Lineage‐Through‐Time (LTT) curve analysis. Further, we conducted mega‐analysis optimised with deliberately assessed 44 calibration points including the revised crown age of Myristicaceae to construct a dated megaphylogeny of angiosperms. Results Our analysis suggests that the crown lineage of Myristicaceae originated ~130 Ma in western Gondwana, and diversified into Myristicoid, Pycnanthoid, and Mauloutchioid clades likely driven by the South America–Africa separation (~120 Ma). The LTT plot shows that Myristicaceae diversification accelerated ~72 Ma, coinciding with the spread of wet tropical climates, and continued post K‐Pg extinction (~65 Ma), indicating resilience to mass extinction events. Further, the revised angiosperm megaphylogeny supports a pre‐Cretaceous origin for basal angiosperms. Main Conclusions Myristicaceae likely originated in western Gondwana during the Early Cretaceous and diversified across palaeotropics ensuing deep‐time Plate tectonism, climate change, and vicariance. The study also proposes a pre‐Cretaceous origin of basal angiosperms in the localised wet‐highland habitats of mid‐ to low paleolatitudes. Overlapping pollen traits between Myristicaceae and earliest angiosperm fossils across Africa and northern mid‐latitudes further suggest a boreotropical expansion of basal angiosperms under wet tropical climates of Cretaceous–Paleogene.