Fossil footprints in the Gombore gully (Melka Kunture, Upper Awash, Ethiopia): A rare snapshot of Pleistocene life and environments

Gombore is a gully of the Melka Kunture archaeological complex in the Upper Awash Valley of Ethiopia. In recent years fossil footprints were brought to light within layers with middle Acheulean lithic industry, or stratigraphically related to them. This is the first time that Pleistocene ichnosurfaces are reported from Ethiopia. Many animal footprints belong to species underrepresented or not represented at all in the fossil record, producing a diversified picture of the prevailing animal community. Overall, hippos, bovids, suids, equids, birds, and possibly a small carnivore and a large lizard are all documented. Hippo footprints are numerous and excellently preserved. This enabled to make casts recording the outer appearance of the leg and foot. A 700.000-year old hippo trail was also discovered and documented [1]. We believe that it was the result of tramping following established trails from resting places to grazing spots, indicating the long ancestry of a behaviour still observed today. Hominins also left direct evidence, i.e. cranial remains, and footprints. The fossil remains, at 850 ka [2], are assigned to a direct ancestor of Homo heidelbergensis [3], the species that we assume produced the 700ka-old footprints of a group including both adults and young children. The associated archaeological and palaeontological record confirms that stone knapping was taking placein situ and that lithic tools were used for butchering hippo carcasses at the site. Most notably, young children – possibly as young as 1-year old, and maybe even less - were standing and witnessing [4]. At 0.85 Ma, furthermore, footprints of young hominins have been found in layers without any associated archaeological record [5]. Footprints are a first-hand source to reconstruct past environments. They provide direct evidence of the behavioral patterns of extinct species, including hominins. We underline that during fieldwork attention should be routinely provided to ichnological evidence, in order to identify and investigate this precious but fragile record with a specific methodology and a documentation protocol supported by technologies such as laser scanning and photogrammetry