Denné Reed

Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia

The oldest direct evidence of stone tool manufacture comes from Gona (Ethiopia) and dates to between 2.6 and 2.5 million years (Myr) ago. At the nearby Bouri site several cut-marked bones also show stone tool use approximately 2.5 Myr ago. Here we report stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia, a research area close to Gona and Bouri. On the basis of low-power microscopic and environmental scanning electron microscope observations, these bones show unambiguous stone-tool cut marks for flesh removal and percussion marks for marrow access. The bones derive from the Sidi Hakoma Member of the Hadar Formation. Established 40Ar–39Ar dates on the tuffs that bracket this member constrain the finds to between 3.42 and 3.24 Myr ago, and stratigraphic scaling between these units and other geological evidence indicate that they are older than 3.39 Myr ago. Our discovery extends by approximately 800,000 years the antiquity of stone tools and of stone-tool-assisted consumption of ungulates by hominins; furthermore, this behaviour can now be attributed to Australopithecus afarensis.

A juvenile early hominin skeleton from Dikika, Ethiopia

Understanding changes in ontogenetic development is central to the study of human evolution. With the exception of Neanderthals, the growth patterns of fossil hominins have not been studied comprehensively because the fossil record currently lacks specimens that document both cranial and postcranial development at young ontogenetic stages. Here we describe a well-preserved 3.3-million-year-old juvenile partial skeleton of Australopithecus afarensis discovered in the Dikika research area of Ethiopia. The skull of the approximately three-year-old presumed female shows that most features diagnostic of the species are evident even at this early stage of development. The find includes many previously unknown skeletal elements from the Pliocene hominin record, including a hyoid bone that has a typical African ape morphology. The foot and other evidence from the lower limb provide clear evidence for bipedal locomotion, but the gorilla-like scapula and long and curved manual phalanges raise new questions about the importance of arboreal behaviour in the A. afarensis locomotor repertoire.

Geological and palaeontological context of a Pliocene juvenile hominin at Dikika, Ethiopia

Since 1999, the Dikika Research Project (DRP; initiated by Z.A.) has conducted surveys and excavations in badlands that expose Pliocene and Pleistocene sediments south of the Awash River in Ethiopia, between surrounding hominin localities at Hadar, Gona and the Middle Awash region. Here we report our geological mapping and stratigraphic measurement of the DRP area, and the context of a remarkably well-preserved skeleton of the earliest known juvenile hominin at the Dikika DIK-1 locality. Our mapping of the DRP area permits a complete definition of the hominin-bearing Hadar Formation and provides a cohesive structural and tectonic framework defining its relationships to adjacent strata. Our findings reveal the basin-scale tectonic, depositional and palaeoenvironmental history of the area, as well as a clear taphonomic and palaeontological context for the juvenile hominin. Such data are crucial for understanding the environmental context of human evolution, and can be integrated into larger-scale tectonic and palaeoenvironmental studies. Our basin-scale approach to palaeoenvironments provides a means to elucidate the complex geological history occurring at the scale of temporally and geographically controlled fossil point localities, which occur within the rich tectonic and depositional history of the Awash Valley.

Serengeti micromammals and their implications for Olduvai Paleoenvironments

Fossil micromammals are widely used as paleoenvironmental indicators in Pliocene hominid fossil localities, and many such assemblages are believed to be accumulated by predators such as owls. This chapter examines modern owl-accumulated micromammal assemblages from Serengeti, Tanzania. The modern roost data are used to examine the fidelity of the taxonomic signal and its sensitivity to change across habitats within an ecosystem. The modern data show that the relative abundance of prey taxa in owl accumulated assemblages varies across habitats in a predictable fashion. This provides a basis for applying the analysis of fossil micromammal assemblages to intra-basin scales using relative abundance as well as biome or regional scales using presence/absence of taxa. Using the modern micromammal assemblages as analogs, the latter part of the chapter explores taphonomic and paleoenvironmental change through Bed I times at Olduvai Gorge.

New excavations at the site of Contrebandiers Cave, Morocco

PaleoAnthropology 2012: 145−201.

Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia

Two fossil specimens from the DIK-55 locality in the Hadar Formation at Dikika, Ethiopia, are contemporaneous with the earliest documented stone tools, and they collectively bear twelve marks interpreted to be characteristic of stone tool butchery damage. An alternative interpretation of the marks has been that they were caused by trampling animals and do not provide evidence of stone tool use or large ungulate exploitation by Australopithecus-grade hominins. Thus, resolving which agents created marks on fossils in deposits from Dikika is an essential step in understanding the ecological and taphonomic contexts of the hominin-bearing deposits in this region and establishing their relevance for investigations of the earliest stone tool use. This paper presents results of microscopic scrutiny of all non-hominin fossils collected from the Hadar Formation at Dikika, including additional fossils from DIK-55, and describes in detail seven assemblages from sieved surface sediment samples. The study is the first taphonomic description of Pliocene fossil assemblages from open-air deposits in Africa that were collected without using only methods that emphasize the selective retention of taxonomically-informative specimens. The sieved assemblages show distinctive differences in faunal representation and taphonomic modifications that suggest they sample a range of depositional environments in the Pliocene Hadar Lake Basin, and have implications for how landscape-based taphonomy can be used to infer past microhabitats. The surface modification data show that no marks on any other fossils resemble in size or shape those on the two specimens from DIK-55 that were interpreted to bear stone tool inflicted damage. A large sample of marks from the sieved collections has characteristics that match modern trampling damage, but these marks are significantly smaller than those on the DIK-55 specimens and have different suites of characteristics. Most are not visible without magnification. The data show that the DIK-55 marks are outliers amongst bone surface damage in the Dikika area, and that trampling is not the most parsimonious interpretation of their origin.

Tool-marked bones from before the Oldowan change the paradigm

Dominguez-Rodrigo et al. (1) critiqued our paper (2), which provided the earliest evidence for stone tool use and animal tissue consumption as evidenced by bones bearing tool-induced marks found at DIK-55 (Dikika, Ethiopia) and dated to 3.39 Ma. Applying a configurational approach, they questioned the bones’ context and without examining or conducting new analysis on the original fossils, argued that all of the Dikika marks resulted from trampling, because a small subset of these marks superficially resembled a small subset of experimentally trampled specimens. Furthermore, they argued (1) that stone tool use and meat consumption before the current consensus dates requires finding manufactured … [↵][1]1To whom correspondence should be addressed. E-mail: mcpherron{at}eva.mpg.de. [1]: #xref-corresp-1-1

Ecological fidelity of functional traits based on species presence- absence in a modern mammalian bone assemblage (Amboseli, Kenya)

Abstract Comparisons between modern death assemblages and their source communities have demonstrated fidelity to species diversity across a variety of environments and taxonomic groups. However, differential species preservation and collection (including body-size bias) in both modern and fossil death assemblages may still skew the representation of other important ecological characteristics. Here, we move beyond live-dead taxonomic fidelity and focus on the recovery of functional ecology (how species interact with their ecosystem) at the community level for a diverse non-volant mammal community (87 species; Amboseli, Kenya). We use published literature to characterize species, using four functional traits and their associated categorical attributes (i) dietary mode (11 attributes; e.g., browser, grazer), (ii) preferred feeding habitat (16 attributes; e.g., grassland, woodland), (iii) preferred sheltering habitat (17 attributes; e.g., grassland, underground cavity), and (iv) activity time (7 attributes; e.g., diurnal, nocturnal, nocturnally dominated crepuscular). For each functional ecological trait we compare the death assemblages recovered richness and abundance structure of constituent functional attributes with those of the source community, using Jaccard similarity, Spearmans rho, and the Probability of Interspecific Encounter (evenness). We use Monte Carlo simulations to evaluate whether these empirical comparisons are significantly different from expectations calculated from randomized sampling of species from the source community. Results indicate that although the Amboseli death assemblage is significantly overrepresented by large-bodied species relative to the Amboseli source community, it captures many functional dimensions of the ecosystem within expectations of a randomized collection of species. Additional resampling simulations and logistic regressions further illustrate that the size bias inherent to the Amboseli death assemblage is not a major driver of deviations between the functional ecological properties of the death assemblage and its source community. Finally, the Amboseli death assemblage also enhances our understanding of the mammal community by adding nine species and two functional attributes previously unknown from the ecosystem.

Evidence for a Late Pliocene faunal transition based on a new rodent assemblage from Oldowan locality Hadar A.L. 894, Afar Region, Ethiopia

The time interval between 3 Ma and 2 Ma marks several important transitions in human evolution, including the extinction of Australopithecus afarensis, the origin of the genus Homo, and the appearance of concentrated stone tool assemblages forming recognizable archaeological sites. The period also marks important changes in Earths climatic history, with the onset of northern hemisphere glaciation starting sometime between 2.8 Ma and 2.5 Ma, and it remains an unresolved question in paleoanthropology whether or not the global climatic events influenced in whole or in part, local terrestrial paleoenvironments in Africa and, through this, the course of human evolution. Changes in the terrestrial mammalian faunas of East Africa during this time interval are an important source of data about terrestrial paleoenvironments, and it has been argued that during this time period the mammalian faunas of Africa experienced a sudden pulse in the extinction and origination of taxa. The data corroborating this Turnover Pulse Hypothesis derive from both large mammal and micromammal data, though the fossil record of the former is much more abundant in this interval. New micromammal fossils recovered from ca. 2.4 Ma deposits at locality A.L. 894, low in the Busidima Formation in the Hadar study area of the Afar region, Ethiopia, reveal a significant faunal turnover when compared with previously published material from older 3.2 Ma micromammal assemblages from the Hadar Formation deposits. The results support the hypothesis of a major faunal transition, but larger sample sizes and more extensive temporal sampling are needed to refine the time and rate of change within this interval at Hadar.

The Taphonomy and Paleoenvironmental Implications of the Laetoli Micromammals

Recent fieldwork conducted between 1998 and 2005 significantly increased the sample of fossil rodent specimens from Laetoli, Tanzania, the type locality of Australopithecus afarensis and this allowed the identification of several new micromammal species. This chapter discusses the taphonomy and paleoenvironmental implications of the Laetoli rodents. The taphonomic analysis of the new material looks at element representation, breakage patterns and bone surface modification and finds evidence of predator activity and weathering. In terms of paleoenvironment, the Upper Laetolil Beds assemblage has a very low abundance of murine rodents, a predominantly arboreal taxon (Thallomys) alongside an arboreal sciurid (Paraxerus), and several fossorial and burrowing taxa, which we interpret to indicate the presence of acacia trees growing on loose, well-drained sediments in a semi-arid environment. The Upper Ndolanya Beds sample remains small, and the species preserved are the same as those found in the Upper Laetolil Beds, with the exception of Thryonomys. This provides tentative evidence for a more mesic local environment in Upper Ndolanya times relative to the Upper Laetolil Beds.