NEOGENE COASTAL-PLAIN ESTUARINE RECORD IN THE GORONGOSA AREA, CENTRAL MOZAMBIQUE: PALEOENVIRONMENTAL AND PALEOECOLOGICAL IMPLICATIONS FOR THE ANCIENT EAST AFRICAN MARGIN AND ITS PRIMATE LAND USE POTENTIAL

A major puzzle in human origins research is the question of where, when, and under what environmental conditions our lineage originated in Africa, but answers are hampered by the scarcity of Mio-Pliocene paleontological sites. To help fill these gaps, the Paleo-Primate Project Gorongosa, a multidisciplinary research initiative on human origins, was initiated at Gorongosa National Park, central Mozambique, in 2016. Despite (a) its location in the Urema Graben, the youngest continental section of the EARS (East African Rift System), (b) the presence of Quaternary karst caves, (c) its bridging key position between the major paleoanthropological sites of South, Central, and East Africa, and (d) previously presented stone-tool evidence for hominin activity, the Gorongosa area is a virtually unexplored region. Here we present the first significant discoveries of fossil vertebrate remains from this part of the EARS. In situ and surface fossil finds recovered from the Neogene Lower Mazamba Formation indicate a rich vertebrate community including mammals, crocodiles, and turtles. Sediment provenance analysis and paleotransport patterns imply a metamorphic source terrane west of today’s Urema Graben and a pre- to early syn-rift age of ≥3±1 Ma (possibly Mio-Pliocene). Sedimentary facies, facies architecture, and a marine invertebrate fossil content suggest a coastal-plain estuarine setting that grades into terrestrially-dominated habitats towards the hinterland, with floral associations comprising dicot tree species and palms. Wet coastal systems such as estuaries have widespread significance in human land use, and they are extremely productive habitats for marine and terrestrial fauna, also including primates. The identification of this nearshore setting, which may well be expected to have had a similar habitat function in the past, represents the first ancient coastal biome in the Neogene EAR context. Further research at Gorongosa will allow us to test key hypotheses of human origins and paleobiogeography during critical periods of our evolution.