3D survey in extreme environment. The case study of Laetoli hominin footprints in Tanzania

Many cultural assets are in risky situations and they are destined to disappear. Sometimes problems are caused by the anthropic component (e.g. wars) or by natural disasters (e.g. earthquakes and landslides). At other times the cause of deterioration is due to the slow and inexorable action of atmospheric agents and other natural factors present in extreme areas, where preservation of Cultural Heritage is more complex. This contribution deals with 3D documentation of paleontological excavations in extreme contexts that are characterized by unfavorable climatic conditions, limited instrumentation and little time available. In particular, the contribution is focused on the search for a good working procedure which, despite the problems mentioned above, can lead to valid results in terms of accuracy and precision, so that subsequent scientific studies are not compromised. The proposed case study concerns the recent discovery of fossil footprints at the Site S in Laetoli, within the Ngorongoro Conservation Area (Tanzania), which is a UNESCO World Heritage Site. With the new discovery of Site S it was necessary to implement a 3D survey operative protocol with limited equipment and in a very short time. The 3D models, obtained through the “Structure from Motion” (SfM) technique and topographic support, were used to perform morphological and morphometric investigations on the new footprints. Through the analysis it was possible to estimate height and weight of the footprint makers (hominins of the species Australopithecus afarensis). The collected evidence supports marked intraspecific variation in this species, pointing out the occurrence of a considerable difference in size between sexes and suggesting inferences on reproductive behavior and social structure of these ancient bipedal hominins. The contribution shows how important is to obtain good 3D documentation, even in extreme environment, in order to reach reliable results for scientific analysis