Within-species variability in body size often relates to sexual dimorphism and/or to adaptation to different ecologies. This leaves open the possibility that additional tracks may be unearthed nearby that will further our knowledge about the variability and behaviour of our extinct ancestors.Įstimates of body size and proportions are crucial in the evolutionary interpretation of Plio-Pleistocene hominin palaeobiology ( McHenry, 1991, 1992 Ruff et al., 1997 Grabowski et al., 2015) and have been the subject of ongoing debates, at least since the late 1970s (e.g., Johanson and White, 1979). The newly discovered tracks are only 150 metres away from the previously discovered sets of footprints. Thus, considerable differences may have existed between males and females in these remote human ancestors, similar to modern gorillas. The tall individual may have been the dominant male of a larger group, the others smaller females and juveniles. tentatively suggest that the new footprints can be considered as a whole with the 1970s ones. This evidence supports the theory that body size varied considerably amongst individuals within the species. The estimated height of one of the new individuals (about 1.65 metres) greatly exceeds those previously published for Au. have now unearthed new bipedal footprints from two individuals who were moving on the same surface and in the same direction as the three individuals who made the footprints documented in the 1970s. Based on the skeletal remains found so far in East Africa, some scholars believe that individuals only varied moderately, as in modern humans, while others state that it was pronounced, as in some modern apes like gorillas. afarensis – for example, between males and females – has been the subject of a long debate among researchers. The extent to which body shape and size varied between different members of Au. These are thought to have been made by three members of the hominin species Australopithecus afarensis – the same species as the famous “Lucy” from Ethiopia – around 3.66 million years ago. The only exceptions are the footprints that were discovered in the 1970s at Laetoli (in Tanzania) on a cemented ash layer produced by a volcanic eruption. Nearly all of the hominin footprints discovered so far are attributed to species of the genus Homo, to which modern humans belong. How did the track-maker move? How large was it? How fast was it going?įootprints of hominins (namely the group to which humans and our ancestors belong) are pretty rare. Their physical features can help to identify their makers, but can also be used to infer biological information. Our results are consistent with considerable body size variation and, probably, degree of sexual dimorphism within a single species of bipedal hominins as early as 3.66 million years ago.įossil footprints are extremely useful tools in the palaeontological record. In combination with a comparative reappraisal of the Site G footprints, the evidence collected here embodies very important additions to the Pliocene record of hominin behaviour and morphology. afarensis from both skeletal material and footprint data. The stature estimates for S1 greatly exceed those previously reconstructed for Au. Here, we report hominin tracks unearthed in the new Site S at Laetoli and referred to two bipedal individuals (S1 and S2) moving on the same palaeosurface and in the same direction as the three hominins documented at Site G. Laetoli is a well-known palaeontological locality in northern Tanzania whose outstanding record includes the earliest hominin footprints in the world (3.66 million years old), discovered in 1978 at Site G and attributed to Australopithecus afarensis.
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