A fundamental challenge for the natural sciences is understanding the distribution of ecosystems. Nowhere has discourse been more contested than in Madagascar around perceived ancient versus anthropogenic grassy ecosystems. Data collected across different disciplines and at varied spatio-temporal scales have produced conflicting inferences about the mosaic of Madagascar's vegetation before the human settlement of the island. Crowley et al.  describe new palaeo-records demonstrating extinct hippos were associated with grassy ecosystems and with different abundances of grassy ecosystems containing a C4 component associated with different bands of elevation across the Central Highlands. These and other recently published data from the Central Highlands [1,2] support the findings of Solofondranohatra et al.  that grazing associated with grassy ecosystems existed in some forms prior to human settlement of the island, but open questions remain around the extent. Here, we propose a research agenda and ecological considerations to help advance understanding of the distribution and dynamics of ecosystems across Madagascar.