The emergence of the tropical rainforest biome in the Cretaceous

Modern tropical rainforests (TRFs) are one of the mostecologically important and species-rich biomes on the planet. However, theorigin of modern TRFs is still debated, especially due to the incongruencebetween the fossil record and molecular data. Here, we test whetherCampanian assemblages from northeastern Africa could represent fossil TRFvegetation. In so doing, we compare the investigated assemblages with otherassemblages known to represent temperate forests, subtropical forests, andTRF in terms of leaf physiognomy, species richness, and taxonomiccomposition. We conclude based on fossil leaves that modern-looking TRFsalready existed since 80 Ma during the Campanian in northeastern Africain an area corresponding to 10 % of the modern Amazonian or 25 % of theCongolese TRF. The apparent conflict between the fossil record andphylogenetic evidence is due to the nearly complete absence of publishedtropical floras for the Cretaceous.