Elsevier Editorial System(tm) for Journal of Human Evolution Manuscript Draft Manuscript Number: Title: Large Mammals and Fish from the Oldowan-Acheulean Transition at Olduvai Gorge, Tanzania, and the Paleoecology of the Serengeti Article Type: SI: Oldowan-Acheulean Keywords: Africa; Pleistocene; large mammals; fish; extinction; defaunation Corresponding Author: Dr. Faysal Bibi, Corresponding Author's Institution: Museum für Naturkunde First Author: Faysal Bibi Order of Authors: Faysal Bibi; Michael Pante; Antoine Souron; Kathlyn Stewart; Sara Varela; Lars Werdelin; Jean-Renaud Boisserie; Mikael Fortelius; Leslea Hlusko; Jackson Njau; Ignacio de la Torre Abstract: Eight years of excavation work by the Olduvai Geochronology and Archaeology Project (OGAP) has produced abundant remains of a rich vertebrate fauna from several sites within and just below Middle Bed II, Olduvai Gorge, Tanzania. Study of these as well as the recently re- organized collections from Mary Leakey's 1972 HWK EE excavations here provides a synthetic view of the faunal community of Olduvai at 1.7-c.1.4 Ma. We expand the faunal list for this interval, including naming a new bovid species, clarify of the evolution of several mammalian lineages, and record new local first and last appearances. Compositions of the fish and large mammal assemblages support previous indications for the dominance of open and seasonal grassland habitats at the margins of paleo-Lake Olduvai. The mammals are mainly dominated by grazing bovids (alcelaphins) and equids, and the taphonomy of the fish assemblages supports reconstructions of fluctuating lake levels with mass die-offs in evaporating pools. No major turnover or paleoecological changes seem to be associated with the transition from Oldowan to Acheulean stone tool technologies within Middle Bed II. Community profiles show that the Middle Bed II large mammal community is much more species-rich and includes a larger number of large-bodied species (> 100 kg) than its modern Serengeti analog. By comparison, extant Serengeti fits the profile of a 'downsized' community, similar to those that have been defaunated by human disturbance rather than by climate change alone. Despite these fundamental differences, trophic network analyses show that the Middle Bed II and extant Serengeti communities bear similar structural properties as concerns the distribution of feeding links among predator and prey species. The presence of a generalized hominin predator increases competition among carnivores and vulnerability among herbivores, but both the paleo- and extant webs include highly generalized predators that are highly resistant to the effects of herbivore extinctions. Both climatic and human-induced hypotheses for the loss of African Pleistocene large mammals require further testing. *Manuscript Click here to view linked References Large Mammals and Fish from the Oldowan-Acheulean Transition at Olduvai Gorge, Tanzania, and the Paleoecology of the Serengeti 1 2 3 4 1* 2 3 4 1 5 5 Faysal Bibi , Michael Pante , Antoine Souron , Kathlyn Stewart , Sara Varela , Lars Werdelin , Jean- 6 6,7 1,8,9 10 11 12 7 Renaud Boisserie , Mikael Fortelius , Leslea Hlusko , Jackson Njau , Ignacio de la Torre . 8 9 10 11 1. Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 12 13 D-10115 Berlin, Germany. [email protected] 14 15 2. Department of Anthropology, Colorado State University, 1787 Campus Delivery, Fort Collins, CO, 16 17 80523, USA. 18 19 3. PACEA, UMR CNRS 5199, Université de Bordeaux, Bâtiment B18, Allée Geoffroy Saint Hilaire, CS 20 21 50023, 33615 PESSAC CEDEX, France. 22 23 4. Research Scientist, Palaeobiology, Canadian Museum of Nature, P O Box 3443, Stn D, Ottawa, Canada 24 25 K1S 0W3. 26 27 Lars Werdelin 28 5. 29 30 6. Centre Français des Études Éthiopiennes, USR 3137, CNRS & Ministère des Affaires Étrangères et du 31 32 dévéloppement international, P.O. Box 5554 Addis Ababa, Ethiopia. 33 34 7. Institut de paléoprimatologie, Paléontologie Humaine : Évolution et Paléoenvironnements, UMR 7262, 35 36 CNRS & Université de Poitiers, 6 rue Michel Brunet, 86000 Poitiers, France 37 38 8. Department of Geosciences and Geography, University of Helsinki, FI-00014 Helsinki, Finland 39 40 9. Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 41 42 NO-0316 Oslo, Norway 43 44 10. Human Evolution Research Center, Department of Integrative Biology, University of California 45 46 Berkeley, CA 94720 47 48 11. Department of Geological Sciences, Indiana University, 1001 E Tenth Street, Bloomington, IN 47405, 49 50 USA 51 52 12. Institute of Archaeology, University College London, 31-34 Gordon Square, WC1H 0PY London, 53 54 United Kingdom 55 56 57 58 59 *corresponding author 60 61 62 63 Page !1 of !65 64 65 Abstract 1 2 3 Eight years of excavation work by the Olduvai Geochronology and Archaeology Project (OGAP) has 4 5 produced abundant remains of a rich vertebrate fauna from several sites within and just below Middle 6 7 Bed II, Olduvai Gorge, Tanzania. Study of these as well as the recently re-organized collections from 8 9 Mary Leakey’s 1972 HWK EE excavations here provides a synthetic view of the faunal community of 10 11 Olduvai at 1.7-c.1.4 Ma. We expand the faunal list for this interval, including naming a new bovid 12 13 species, clarify of the evolution of several mammalian lineages, and record new local first and last 14 15 appearances. Compositions of the fish and large mammal assemblages support previous indications for 16 17 the dominance of open and seasonal grassland habitats at the margins of paleo-Lake Olduvai. The 18 19 mammals are mainly dominated by grazing bovids (alcelaphins) and equids, and the taphonomy of the 20 21 fish assemblages supports reconstructions of fluctuating lake levels with mass die-offs in evaporating 22 23 pools. No major turnover or paleoecological changes seem to be associated with the transition from 24 25 Oldowan to Acheulean stone tool technologies within Middle Bed II. 26 27 Community profiles show that the Middle Bed II large mammal community is much more 28 29 30 species-rich and includes a larger number of large-bodied species (> 100 kg) than its modern Serengeti 31 32 analog. By comparison, extant Serengeti fits the profile of a ‘downsized’ community, similar to those that 33 34 have been defaunated by human disturbance rather than by climate change alone. Despite these 35 36 fundamental differences, trophic network analyses show that the Middle Bed II and extant Serengeti 37 38 communities bear similar structural properties as concerns the distribution of feeding links among 39 40 predator and prey species. The presence of a generalized hominin predator increases competition among 41 42 carnivores and vulnerability among herbivores, but both the paleo- and extant webs include highly 43 44 generalized predators that are highly resistant to the effects of herbivore extinctions. Both climatic and 45 46 human-induced hypotheses for the loss of African Pleistocene large mammals require further testing. 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 Page !2 of !65 64 65 Introduction 1 2 3 Fieldwork by the Olduvai Geochronology and Archaeology Project (OGAP) since 2008 has produced a large 4 5 vertebrate fauna from Middle Bed II at Olduvai Gorge, Tanzania. The Olduvai fossil fauna, particularly the 6 7 large mammals of Bed I, are well known from previous collections, mainly from excavations led by Hans 8 9 Reck and then Louis and Mary Leakey (reviewed in Leakey, 1978). 10 11 The main fossiliferous beds at Olduvai are numbered from Bed I to IV (Fig. 1), from oldest to 12 13 youngest, following the original stratigraphy developed by Hans Reck (e.g. in Leakey, 1951). Geological 14 15 work over the last 100 years has clarified the chronostratigraphy at Olduvai. Bed I is the best constrained 16 17 level, dated to 2.038-1.803 Ma (Deino, 2012), and is divided into Lower, Middle, and Upper units. Bed II is 18 19 also divided into Lower, Middle, and Upper units (Leakey, 1971a), but dating is not as precise as for Bed I. 20 21 The Bed II fauna has sometimes been treated as a single assemblage though the presence of at least several 22 23 depositional hiatuses (unconformities) means that Bed II could span some 600,000 years (1.8-1.2 Ma, 24 25 McHenry et al., 2016). Leakey (1971a) placed the boundary between Lower and Middle Bed II at the top of 26 27 Tuff IIA, but Hay (1976b) later formally defined the Lemuta Member, of which Tuff IIA is just the middle of 28 29 30 three 'tongues' of eolian tuffaceous sediment to the east. Following de la Torre et al. (this volume "New 31 32 Excavations at the HWK EE" site; also Stanistreet et al, in prep, this volume "Stratigraphy of Middle Bed 33 34 II") the disconformity at the bottom of the Lower Augitic Sandstone is now proposed as the boundary 35 36 between Lower and Middle Bed II. Tuff IIC defines the boundary between Middle and Upper Bed II (Fig. 1). 37 38 Tuff IIA, often found just below the Lower Augitic Sandstone, is dated to 1.71 Ma (Curtis and Hay, 1972). 39 40 The Bird Print Tuff (BPT), found slightly above Tuff IIB, is correlated with a tuff dated to 1.664 Ma (Diez- 41 42 Martín et al., 2015) (also McHenry and Deino, in prep, this volume "Tephrochnology of Middle Bed II"). 43 44 Tuff IIC is not dated. Tuff IID is around 1.34 Ma in age (Domínguez-Rodrigo et al., 2013). 45 46 This article presents the large mammals and fish from new Bed II collections recovered by OGAP as 47 48 well as the large collections from Mary Leakey’s 1972 excavations of the HWK-EE site.