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Biogeographic and Evolutionary Implications of an Extinct Late Pleistocene Impala from the Lake Victoria Basin, Kenya
Abstract
This study contributes to the growing complexity of the impala fossil record through a morphological description and analysis of Aepyceros fossils from late Pleistocene deposits in Kenya’s Lake Victoria Basin. We show that the Lake Victoria impala belongs to an extinct species that differs from modern impala and its fossil predecessors by a combination of exceptionally deep mandibles and teeth characterized by greater hypsodonty and occlusal lengths. Whereas modern impala (A. melampus) displays substantial ecological flexibility, these traits in the extinct species suggest a more dedicated adaptation to grazing in open and dry environments. Previous phylogeographic observations indicate that A. melampus was extirpated from East Africa, perhaps during the middle-to-late Pleistocene, and later recolonized from southern Africa. The Lake Victoria impala raises the possibility that the evidence interpreted as extirpation may instead reflect speciation, with A. melampus giving rise to a novel East African species while persisting unchanged in southern Africa. Increased rainfall and rising atmospheric CO2 concentrations at the end of the Pleistocene may have played a role in the disappearance of the extinct form via habitat loss and possibly competition with the more versatile A. melampus.
... These beds are discontinuously exposed over an area of ~40 km 2 and are up to 10.5 m in thickness, overlying eroded topography of Miocene bedrock (Pickford, 1984). The Pleistocene deposits are best exposed at the localities of Kisaaka, Aringo, Aoch Nyasaya and Obware (Figs. 4, 5, 6;Faith et al., 2014), with the most extensive and thickest exposures at Kisaaka (Figs. 3, 4;Beverly et al., 2015b;Faith et al., 2015). The deposits are Karungu are comprised of fine grained siltstone and mudstone beds that have been pedogenically modified into paleo-Vertisols and paleo-Inceptisols, conglomeratic beds that represent fluvial channels, variably reworked tephra, and tufas deposited by local springs (Beverly et al., 2015b; . ...
... Fauna from the eLVB and most localities in the Wasiriya beds are abundant and collectively constitute one of the largest and most diverse Late Pleistocene faunal assemblages in East Africa Faith et al., 2012;Faith et al., 2014;Faith et al., 2015;Garrett et al., 2015;. The eLVB and the Wasiriya beds in general include both extinct and extant taxa . ...
... The eLVB and the Wasiriya beds in general include both extinct and extant taxa . The majority of specimens indicate open, semi-arid grasslands distinct from the evergreen bushlands, woodlands, and forests historically found in the region and otherwise common (Faith et al., 2011;Faith et al., 2012;Faith et al., 2014;Faith et al., 2015;Garrett et al., 2015;Tryon et al., 2010;Tryon et al., 2012). The Nyamita Valley follows the general open-arid pattern seen in the rest of the eLVB . ...
The later Middle through early Late Pleistocene (~100–400 ka) of East Africa is an important time and place for the evolution of our species. This period records the first appearance of Homo sapiens and spans significant technological changes including the decline of large handheld stone tools characteristic of the Acheulean, the development of stone tool technologies collectively known as the Middle Stone Age (MSA). These include diverse Levallois prepared core techniques and the manufacture and use of pointed weapons. It is in association with MSA technologies in sub-Saharan Africa that most of the behaviors characteristic of modern humans first appear. This doctoral dissertation provides new chronological and archaeological data relevant to hominin behavior associated with MSA technology in the Middle and Late Pleistocene of East Africa. Improved chronological resolution is achieved through tephrostratigraphy, the correlation of volcanic ashes, combined with chronometric dating in two regions: the Kapthurin Formation in the Rift Valley, Baringo, Kenya and the eastern Lake Victoria Basin of western Kenya. New data on hominin behavior is provided by archaeological excavations of two sites: 1) The 196-226 ka Sibilo School Road Site in the Kapthurin Formation. 2) The 33–49 ka site of Nyamita Main in the eastern Lake Victoria Basin. The archaeology of the Kapthurin Formation and the eastern Lake Victoria Basin are connected thematically by the presence of MSA technology. These basins are also connected stratigraphically and chronologically, as this study shows, by tephra correlations between them. Results of this work demonstrate: 1) Levallois prepared core techniques, important aspects of MSA technology, are shown to be >380 ka in the Kapthurin Formation, ~100 kyr older than previously estimated in East Africa. 2) Long distance transport (>166 km) of high quality obsidian for stone tool manufacture was a feature of hominin behavior associated with Middle Pleistocene MSA technology ~200 ka ago. 3) MSA technology persisted in East Africa later than 49 ka and perhaps later than 33 ka, after Later Stone Age technologies, often considered categorically superior, are documented in the region. By demonstrating both the early and late presence of various aspects of MSA technology and associated hominin behavior this work shows that tephrostratigraphy and the excavation of new archaeological material in East Africa are productive means of producing new and important data on the MSA and the evolution of human behavior.
... The sediments at Karungu preserve abundant vertebrate fossils and Middle Stone Age (MSA) artifacts (Owen, 1937;Pickford, 1984;, which are considered the archeological signature of early H. sapiens in East Africa (McBrearty and Brooks, 2000;Tryon and Faith, 2013). The pre-LGM Karungu dataset complements, refines, and expands those from correlative deposits on Rusinga and Mfangano Islands~40 km to the north (Tryon et al., 2010;Faith et al., 2011;Van Plantinga, 2011;Faith et al., 2012;Tryon et al., 2012;Faith et al., 2014;Tryon et al., 2014;Garrett et al., 2015). Previous evidence from MSA archeological and paleontological sites from Rusinga and Mfangano Islands suggests that the contraction of Lake Victoria and expansion of grasslands during the late Pleistocene may have facilitated the dispersal of large-bodied mammals, including humans, across Africa (e.g., Faith Blegen et al. (2015). ...
... Karungu (0.84°S, 34.15°E) is located on the Kenyan margin of Lake Victoria (Fig. 1),~40 km south of Pleistocene localities on Rusinga and Mfangano Islands that have been the focus of research by our team since 2009 (Tryon et al., 2010;Faith et al., 2011;Van Plantinga, 2011;Faith et al., 2012;Tryon et al., 2012;Faith et al., 2014;Tryon et al., 2014;Beverly et al., 2015;Garrett et al., 2015). The Pleistocene deposits at Karungu are exposed at seven sites around the town of Sori. ...
... The presence of gregarious and migratory grazers on Mfangano Island, which is too small to support viable populations of large ungulates, suggests a connection to the mainland. This requires a lake-level decline of at least 25 m (Tryon et al., 2010Faith et al., 2011Faith et al., , 2012Faith et al., , 2014 and comparisons with existing models suggest that such a decline is only possible with a significant rainfall reduction (Broecker et al., 1998;Milly, 1999). Analyses by Faith (2013) indicate peak ungulate diversity in sub-Saharan African game reserves at~800 mm yr −1 and evidence from the paleosols provide quantitative support to explain this high diversity of ungulates. ...
The effect of changing environment on the evolution of Homo sapiens is heavily debated, but few data are available from equatorial Africa prior to the last glacial maximum. The Karungu deposits on the northeast coast of Lake Victoria are ideal for paleoenvironmental reconstructions and are best studied at the Kisaaka site near Karunga in Kenya (94 to N33 ka) where paleosols, fluvial deposits, tufa, and volcaniclastic deposits (tuffs) are exposed over a ~2 km transect. Three well-exposed and laterally continuous paleosols with intercalated tuffs allow for reconstruction of a succession of paleocatenas. The oldest paleosol is a smectitic paleo-Vertisol with saline and sodic properties. Higher in the section, the paleosols are tuffaceous paleo-Inceptisols with Alfisol-like soil characteristics (illuviated clay). Mean annual precipitation (MAP) proxies indicate little change through time, with an average of 764 ± 108 mm yr −1 for Vertisols (CALMAG) and 813 ± 182 to 963 ± 182 mm yr −1 for all paleosols (CIA-K). Field observations and MAP proxies suggest that Karungu was significantly drier than today, consistent with the associated faunal assemblage, and likely resulted in a significantly smaller Lake Victoria during the late Pleistocene. Rainfall reduction and associated grassland expansion may have facilitated human and faunal dispersals across equatorial East Africa.
... The Late Pleistocene geology, fossils and MSA artefacts from Rusinga and Mfangano Islands have been the focus of research since 2009 (Tryon et al., 2010Faith et al., 2011Faith et al., , 2012Faith et al., , 2014Van Plantinga, 2011). The Pleistocene deposits on Rusinga Island, informally designated the 'Wasiriya Beds' by Pickford (1984), unconformably overlie a complex Miocene palaeotopography and are predominately comprised of tuffaceous alluvial and fluvial sediments intercalated with palaeosols that formed during periods of landscape stability, variably reworked tephra and rare tufa deposits (Tryon et al., 2010Van Plantinga, 2011). ...
... Previous research has shown that the Pleistocene deposits surrounding Lake Victoria yield an abundance of well-preserved fossils and MSA ar-tefacts (e.g. Owen, 1937;Kent, 1944;Pickford, 1984;Behrensmeyer et al., 1995;Ditchfield et al., 1999;Plummer et al., 1999;Tryon et al., 2010Tryon et al., , 2012Tryon et al., , 2014Faith et al., 2011Faith et al., , 2012Faith et al., , 2013Faith et al., , 2014Van Plantinga, 2011;Garrett et al., in press). Stone artefacts from Rusinga Island and Karungu include flakes, blades, retouched points and Levallois cores, consistent with a MSA attribution Faith et al., in press b), the industry associated with the earliest modern humans. ...
... The fauna are dominated by alcelaphine bovids (wildebeest and allies) and equids, suggesting environments that were grassier and probably drier than the evergreen bushland, thicket and woodland found in the region today. Oryx (Oryx beisa) and Grevy's zebra (Equus grevyi), which prefer arid to semiarid grasslands and shrublands, and extinct antelopes adapted to grazing in dry grasslands, indicate that the environment was significantly more arid than at present (Tryon et al., 2010Faith et al., 2011Faith et al., , 2012Faith et al., , 2013Faith et al., , 2014. Carbon isotopes of mammalian tooth enamel indicate a diet of predominately C 4 grasses (Garrett et al., in press; Faith et al., in press b). ...
The effect of changing palaeoclimate and palaeoenvironment on human evolution during the Pleistocene is debated, but hampered by few East African records directly associated with archaeological sites prior to the Last Glacial Maximum. Middle to Late Pleistocene deposits on the shoreline of eastern Lake Victoria preserve abundant vertebrate fossils and Middle Stone Age arte-facts associated with riverine tufas at the base of the deposits, which are ideal for palaeoenvironmental reconstructions. New data from tufas identified on Rusinga Island and on the mainland near Karungu, Kenya are provided from outcrop, thin sections, mineralogical, stable isotopic and U-series dating analyses. Tufa is identified in four sites: Nyamita (94·0 ± 3·3 and 111·4 ± 4·2 ka); Kisaaka, Aringo (455 ± 45 ka); and Obware. The age ranges of these tufa deposits demonstrate that spring-fed rivers were a recurrent, variably preserved feature on the Pleistocene landscape for ca 360 kyr. Poor sorting of clastic facies from all sites indicates flashy, ephemeral discharge, but these facies are commonly associated with barrage tufas, paludal environments with δ13C values of ca 10‰ indicative of C3 plants and fossil Hippopotamus, all of which indicate a perennial water source. Other tufa deposits from Nyamita, Obware and Aringo have a mixed C3/C4 signature consistent with a semi-arid C4 grassland surrounding these spring-fed rivers. The δ18O values of tufa from Nyamita are on average ca 1‰ more negative than calcite precipitated from modern rainfall in the region, suggesting greater contribution of depleted monsoonal input, similar to the Last Glacial Maximum. Microdebitage and surface-collected artefacts indicate that early modern humans were utilizing these spring-fed rivers. The presence of spring−fed rivers would have afforded animals a reliable water source, sustaining a diverse plant and animal community in an otherwise arid environment.
... When compared to the proportion of species in other tribal pairs such as Bovini and Reduncini, representing wetter, closed habitats, and Tragelaphini plus Aepycerotini (the impala, Aepyceros melampus), indicating dry and closed habitats, this criterion was understood to be a powerful predictor of paleoenvironment, particularly gross vegetation physiognomy. However, despite strong evidence that ecological similarities in closely-related bovid taxa may be the result of evolutionary constraint and canalization of traits, not all tribes have had such stable ecological strategies over the same time scales (Sponheimer and Lee-Thorp 2003;Faith et al. 2014;Behrensmeyer 2015;Cerling et al. 2015) or are known to include species that are evolutionarily sensitive to ecological change, such as the alcelaphine hartebeest, Alcelaphus buselaphus (e.g., Flagstad et al. 2001) or the impala and its extinct relatives in the genus Aepyceros (Faith et al. 2014). For reasons such as these, indicator species are approached with some caution. ...
... When compared to the proportion of species in other tribal pairs such as Bovini and Reduncini, representing wetter, closed habitats, and Tragelaphini plus Aepycerotini (the impala, Aepyceros melampus), indicating dry and closed habitats, this criterion was understood to be a powerful predictor of paleoenvironment, particularly gross vegetation physiognomy. However, despite strong evidence that ecological similarities in closely-related bovid taxa may be the result of evolutionary constraint and canalization of traits, not all tribes have had such stable ecological strategies over the same time scales (Sponheimer and Lee-Thorp 2003;Faith et al. 2014;Behrensmeyer 2015;Cerling et al. 2015) or are known to include species that are evolutionarily sensitive to ecological change, such as the alcelaphine hartebeest, Alcelaphus buselaphus (e.g., Flagstad et al. 2001) or the impala and its extinct relatives in the genus Aepyceros (Faith et al. 2014). For reasons such as these, indicator species are approached with some caution. ...
Fundamentally rooted in Odum’s niche concept, mammal community studies are based on the understanding that each resident species reveals information about its environment through its adaptations to specific resources and landscape features. Ecologists view the community’s profile of strategies for exploiting particular spatial and dietary niches; a quantitative summary of these strategies when compared across locales from a variety of habitat types demonstrates striking similarities in the communities that live in similar habitats regardless of their location. Recognizing that communities can be compared across space, paleoecologists implemented community studies across time in an effort to reconstruct past environments. This synecological approach to paleoenvironmental reconstruction may be thought of as holistic, since it is not restricted to a single mammal family. However, thorough explorations of how fossil and extant communities differ have revealed significant dissimilarities brought about by the taphonomic history of paleontological assemblages. Techniques have been developed for addressing differences between the modern comparative community sample and the paleontological sample to which it is compared, but recent research conducted by both neo- and paleoecologists has suggested that there are unappreciated differences between modern habitats, as well.
... When compared to the proportion of species in other tribal pairs such as Bovini and Reduncini, representing wetter, closed habitats, and Tragelaphini plus Aepycerotini (the impala, Aepyceros melampus), indicating dry and closed habitats, this criterion was understood to be a powerful predictor of paleoenvironment, particularly gross vegetation physiognomy. However, despite strong evidence that ecological similarities in closely-related bovid taxa may be the result of evolutionary constraint and canalization of traits, not all tribes have had such stable ecological strategies over the same time scales (Sponheimer and Lee-Thorp 2003;Faith et al. 2014;Behrensmeyer 2015;Cerling et al. 2015) or are known to include species that are evolutionarily sensitive to ecological change, such as the alcelaphine hartebeest, Alcelaphus buselaphus (e.g., Flagstad et al. 2001) or the impala and its extinct relatives in the genus Aepyceros (Faith et al. 2014). For reasons such as these, indicator species are approached with some caution. ...
... When compared to the proportion of species in other tribal pairs such as Bovini and Reduncini, representing wetter, closed habitats, and Tragelaphini plus Aepycerotini (the impala, Aepyceros melampus), indicating dry and closed habitats, this criterion was understood to be a powerful predictor of paleoenvironment, particularly gross vegetation physiognomy. However, despite strong evidence that ecological similarities in closely-related bovid taxa may be the result of evolutionary constraint and canalization of traits, not all tribes have had such stable ecological strategies over the same time scales (Sponheimer and Lee-Thorp 2003;Faith et al. 2014;Behrensmeyer 2015;Cerling et al. 2015) or are known to include species that are evolutionarily sensitive to ecological change, such as the alcelaphine hartebeest, Alcelaphus buselaphus (e.g., Flagstad et al. 2001) or the impala and its extinct relatives in the genus Aepyceros (Faith et al. 2014). For reasons such as these, indicator species are approached with some caution. ...
... yield an average mesowear score of 1.33 compared to the score of 0.98 for recent impala (Kaiser et al., 2013) suggesting the Late Quaternary forms had a relatively more abrasive diet than living conspecifics. Living representatives of Aepyceros are variable mixed feeders (Fritz and Bourgarel, 2013), although Faith et al. (2014) reported a large-bodied and hypsodont Late Pleistocene species of Aepyceros from Kenya that was likely a specialized grazer. ...
... It was long argued that the East African faunal community was essentially modern in taxonomic composition by roughly 400,000 years ago (Potts and Deino, 1995;Potts, 1998), although Marean (1992) showed that the Late Pleistocene record at Lukenya Hill was dominated by a small extinct alcelaphin now attributed to Damaliscus hypsodon and also included extinct longhorn buffalo (Syncerus antiquus). Recent work in the Late Pleistocene sediments surrounding Lake Victoria has documented a previously unrecognized array of extinct bovid species (Tryon et al., 2010;Faith et al., 2011Faith et al., , 2012Tryon et al., 2012;Faith et al., 2014;Tryon et al., 2014;Faith et al., in press). The recognition of the extinct alcelaphins Damaliscus hypsodon, Rusingoryx atopocranion, and Megalotragus, in addition to the extinct bovin Syncerus antiquus and a large-bodied hypsodont impala, in southern Kenya less than 100,000 years ago has significantly altered views of the timing of turnover in Pleistocene faunas in East Africa. ...
The Kibish Formation of southern Ethiopia has yielded the earliest fossils of Homo sapiens, ca. 196 ka, and has thus figured prominently in discussions of the origins of modern humans. Here we describe the fossil Bovidae from the Kibish Formation, a record that spans the late Middle Pleistocene to the early to mid-Holocene, and reconstruct aspects of their dietary ecology using mesowear analyses. All of the Kibish bovids represent extant taxa with the exception of the extinct blesbok-like alcelaphin Damaliscus hypsodon; extinct arid-adapted forms Syncerus antiquus and Megalotragus, common in other Late Quaternary sites, are notably absent. Mesowear of the Kibish bovids suggests that the Late Quaternary specimens were characterized by diets with considerably more abrasion-dominated wear relative to their extant conspecifics. Finally, the Kibish record provides supporting evidence for recent phylogeographic hypotheses by demonstrating significant range expansions of Aepyceros melampus, Connochaetes taurinus, Hippotragus equinus, and, to a lesser extent, Kobus kob in the late Middle Pleis-tocene through the early to mid-Holocene coincident with humid phases that punctuated dry spells of the Late Quaternary.
... The fossil record provides the requisite empirical evidence for testing this hypothesis. Compared to the record from southern Africa, which has been a focus of modern human origins research for decades, our understanding of the fossil history of East African ungulates over the last *200 kyr is only beginning to come to light (Marean and Gifford-Gonzalez 1991;Marean 1992;Assefa 2006;Assefa et al. 2008;Faith et al. 2011Faith et al. , 2012Faith et al. , 2014. However, the emerging evidence provides compelling examples of climate-driven range shifts that are consistent with hypotheses derived from ungulate biogeography. ...
... Alcelaphine bovids and equids dominate the assemblages, indicating the presence of open grassland vegetation distinct from the historic vegetation (White 1983). Several extinct bovids are present, including Rusingoryx atopocranion, Damaliscus hypsodon, Megalotragus sp., Syncerus antiquus, and an unnamed impala, all of which are characterized by dental or postcranial adaptations to grazing in open habitats (Klein 1980(Klein , 1994Faith et al. 2011Faith et al. , 2012Faith et al. , 2014. The presence of large gregarious grazers on Mfangano Island, some of which are migratory species, suggests a likely connection to the mainland when the deposits accumulated, requiring a ≥25 m reduction in lake level ). ...
To better understand the potential role of environmental change in mediating human dispersals across equatorial
East Africa, this study examines the biogeographic histories of ungulates, including a summary of current knowledge and fossil evidence stemming from our fieldwork in the Kenyan portion of the Lake Victoria
basin. Phylogeographic and paleontological evidence indicates that vegetation changes across Quaternary climate cycles mediated ungulate distributions and dispersals via the opening and closing of biogeographic barriers
in equatorial East Africa. Dispersal capabilities would have been enhanced during phases of grassland expansion and diminished during phases of grassland contraction. We propose that the distribution and dispersal of diagnostic technological markers in the archaeological record may be similarly influenced by environmental changes. The Middle Stone Age record from the Lake Victoria region provides intriguing examples of possible environmentally mediated technological dispersals.
... yield an average mesowear score of 1.33 compared to the score of 0.98 for recent impala (Kaiser et al., 2013) suggesting the Late Quaternary forms had a relatively more abrasive diet than living conspecifics. Living representatives of Aepyceros are variable mixed feeders (Fritz and Bourgarel, 2013), although Faith et al. (2014) reported a large-bodied and hypsodont Late Pleistocene species of Aepyceros from Kenya that was likely a specialized grazer. ...
... It was long argued that the East African faunal community was essentially modern in taxonomic composition by roughly 400,000 years ago (Potts and Deino, 1995;Potts, 1998), although Marean (1992) showed that the Late Pleistocene record at Lukenya Hill was dominated by a small extinct alcelaphin now attributed to Damaliscus hypsodon and also included extinct longhorn buffalo (Syncerus antiquus). Recent work in the Late Pleistocene sediments surrounding Lake Victoria has documented a previously unrecognized array of extinct bovid species (Tryon et al., 2010;Faith et al., 2011Faith et al., , 2012Tryon et al., 2012;Faith et al., 2014;Tryon et al., 2014;Faith et al., in press). The recognition of the extinct alcelaphins Damaliscus hypsodon, Rusingoryx atopocranion, and Megalotragus, in addition to the extinct bovin Syncerus antiquus and a large-bodied hypsodont impala, in southern Kenya less than 100,000 years ago has significantly altered views of the timing of turnover in Pleistocene faunas in East Africa. ...
... In addition to R. atopocranion and D. hypsodon, extinct bovids include the long-horn buffalo (Syncerus antiquus), giant wildebeest (Megalotragus sp.), and a large-bodied and very hypsodont impala (Aepyceros sp. nov.; Faith et al., 2014), all of which are characterized by specialized grassland adaptations (e.g., large body size or extreme hypsodonty; Faith, 2014). In addition to these extinct taxa, several of the extant ungulate species at Karungu occur well outside (~250e500 km) their historic geographic ranges ( Fig. 8), including Grevy's zebra, white rhinoceros (Ceratotherium simum), oryx, and southern reedbuck (Redunca arundinum). ...
... nov. ( Faith et al., 2011Faith et al., , 2012Faith et al., , 2014Faith, 2014). Of these, only S. antiquus and D. hypsodon are known from other Late Pleistocene faunal assemblages in East Africa ( Marean and Gifford-Gonzalez, 1991;Marean, 1992;Faith et al., 2012;Rowan et al., 2015). ...
The opening and closing of the equatorial East African forest belt during the Quaternary is thought to have influenced the biogeographic histories of early modern humans and fauna, although precise details are scarce due to a lack of archaeological and paleontological records associated with paleoenvironmental data. With this in mind, we provide a description and paleoenvironmental reconstruction of the Late Pleistocene Middle Stone Age (MSA) artifact- and fossil-bearing sediments from Karungu, located along the shores of Lake Victoria in western Kenya. Artifacts recovered from surveys and controlled excavations are typologically MSA and include points, blades, and Levallois flakes and cores, as well as obsidian flakes similar in geochemical composition to documented sources near Lake Naivasha (250 km east). A combination of sedimentological, paleontological, and stable isotopic evidence indicates a semi-arid environment characterized by seasonal precipitation and the dominance of C4 grasslands, likely associated with a substantial reduction in Lake Victoria. The well-preserved fossil assemblage indicates that these conditions are associated with the convergence of historically allopatric ungulates from north and south of the equator, in agreement with predictions from genetic observations. Analysis of the East African MSA record reveals previously unrecognized north-south variation in assemblage composition that is consistent with episodes of population fragmentation during phases of limited dispersal potential. The grassland-associated MSA assemblages from Karungu and nearby Rusinga Island are characterized by a combination of artifact types that is more typical of northern sites. This may reflect the dispersal of behavioral repertoires-and perhaps human populations-during a paleoenvironmental phase dominated by grasslands.
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... However, the impact of these studies is limited because the relevant data archivesdparticularly proxies for temperature, moisture availability, and vegetationdare poorly resolved spatially and temporally (reviewed in Blome et al., 2012). Available faunal evidence indicates that early modern human populations in East Africa were part of extinct non-analog animal communities that were distinct in terms of taxonomic composition compared with regional modern mammal communities (Marean and Gifford-Gonzalez, 1991;Marean, 1992Marean, , 1997Tryon et al., 2010;Faith et al., 2011;Faith et al., 2012Faith et al., , 2013Faith et al., , 2014Tryon et al., 2012), and, as such, the paleoecology of these ancient populations remains poorly understood. Previous paleoenvironmental reconstructions of East African MSA sites using isotopic data have been restricted to the analysis of paleosols from site A5 (dated to~100e80 ka) at Aduma, Ethiopia (Yellen et al., 2005), and no published studies to date have examined the stable isotope composition of fossil mammals from this interval. ...
... The Pleistocene faunas from Rusinga and Mfangano (Table 1) contain the largest number of extinct species of any Pleistocene site in East Africa during the last~400 kyr (cf. Marean, 1992;Assefa et al., 2008;Domínguez-Rodrigo et al., 2008;Faith et al., 2011Faith et al., , 2012Faith et al., , 2013Faith et al., , 2014, with the extinct species Rusingoryx atopocranion (Pickford and Thomas, 1984;Faith et al., 2011) and Damaliscus hypsodon being the most abundant. Relevant to paleoenvironmental reconstruction, the faunas include several taxa indicating locally wet conditions, such as Hippopotamus and two species of reduncine bovids. ...
... The first approach e developing in the 1970s and continuing in ever-more refined ways today e focuses on paleoenvironmental reconstruction, mainly based on relative taxonomic abundance (e.g., Gramly, 1976;Marean, 1992b;Marean and Gifford-Gonzalez, 1991;Mehlman, 1989) and the identification of extinct fauna (Faith, 2014;Faith et al., 2011Faith et al., , 2014Rowan et al., 2015;Tryon et al., 2012). Such reconstructions have demonstrated the importance of open grasslands for Late Pleistocene eastern African hunters. ...
... The late Pleistocene large mammal communities were composed of numerous extinct taxa, some of which were dominant members of the region's faunas until the onset of the Holocene (MacInnes, 1956;Marean and Gifford-Gonzalez, 1991;Marean, 1992;Faith et al., 2015;Lesur et al., 2016;Tryon et al., 2016). This emerging perspective has been reinforced by ongoing research in the Kenyan portions of the Lake Victoria Basin since 2008, which has documented numerous extinct taxa (Rusingoryx atopocranion, Damaliscus hypsodon, Kolpochoerus, and others) in late Pleistocene sediments, including new species or those formerly thought to have disappeared from eastern Africa during the middle Pleistocene (e.g., Tryon et al., 2010Tryon et al., , 2012Tryon et al., , 2016Faith et al., 2011Faith et al., , 2014Faith et al., , 2015Jenkins et al., 2017). These new data show that Homo sapiens in eastern Africa evolved among nonanalog faunal communities (e.g., Faith et al., 2016), as has long been recognized for southern Africa (e.g., Klein, 1980). ...
Rusingoryx atopocranion is an extinct alcelaphin bovid from the late Pleistocene of Kenya, known for its distinctive hollow nasal crest. A bonebed of R. atopocranion from the Lake Victoria Basin provides a unique opportunity to examine the nearly complete postcranial ecomorphology of an extinct species, and yields data that are important to studying paleoenvironments and human-environment interaction. With a comparative sample of extant African bovids, we used discriminant function analyses to develop statistical ecomorphological models for 18 skeletal elements and element portions. Forelimb and hin-dlimb element models overwhelmingly predict that R. atopocranion was an open-adapted taxon. However, the phalanges of Rusingoryx are remarkably short relative to their breadth, a morphology outside the range of extant African bovids, which we interpret as an extreme open-habitat adaptation. It follows that even recently extinct fossil bovids can differ in important morphological ways relative to their extant counterparts, particularly if they have novel adaptations for past environments. This unusual phalanx morphology (in combination with other skeletal indications), mesowear, and dental enamel stable isotopes, demonstrate that Rusingoryx was a grassland specialist. Together, these data are consistent with independent geological and paleontological evidence for increased aridity and expanded grassland habitats across the Lake Victoria Basin.
... Geologic and tephrostratigraphic research around the region has demonstrated that deposits correlative to the Wasiriya Beds exist across several hundred square kilometers on Mfangano Island and along the eastern shore of Lake Victoria Faith et al., 2015;Blegen et al., 2015Blegen et al., , 2017. This research on Rusinga Island and the surrounding region has added many new details to our understanding of the geology, archaeology, and fossil assemblages of the region, which has allowed for studies of the archaeological and paleoecological change during the Late Pleistocene (Tryon et al., 2010Faith et al., 2011Faith et al., , 2014Faith et al., , 2015Garrett et al., 2015;Van Plantinga, 2011;Beverly et al., 2015aBeverly et al., , b, 2017Blegen et al., 2015Blegen et al., , 2017Jenkins et al., 2017). ...
In 2010, a hominin right humerus fragment (KNM-RU 58330) was surface collected in a small gully at Nyamita North in the Late Pleistocene Wasiriya Beds of Rusinga Island, Kenya. A combination of stratigraphic and geochronological evidence suggests the specimen is likely between ∼49 and 36 ka in age. The associated fauna is diverse and dominated by semiarid grassland taxa. The small sample of associated Middle Stone Age artifacts includes Levallois flakes, cores, and retouched points. The 139 mm humeral fragment preserves the shaft from distal to the lesser tubercle to 14 mm below the distal end of the weakly projecting deltoid tuberosity. Key morphological features include a narrow and weakly marked pectoralis major insertion and a distinctive medial bend in the diaphysis at the deltoid insertion. This bend is unusual among recent human humeri but occurs in a few Late Pleistocene humeri. The dimensions of the distal end of the fragment predict a length of 317.9 ± 16.4 mm based on recent samples of African ancestry. A novel method of predicting humeral length from the distance between the middle of the pectoralis major and the bottom of the deltoid insertion predicts a length of 317.3 mm ± 17.6 mm. Cross-sectional geometry at the midshaft shows a relatively high percentage of cortical bone and a moderate degree of flattening of the shaft. The Nyamita humerus is anatomically modern in its morphology and adds to the small sample of hominins from the Late Pleistocene associated with Middle Stone Age artifacts known from East Africa. It may sample a population closely related to the people of the out-of-Africa migration.
... The Late Pleistocene geology, fossils, and MSA artifacts from Rusinga and Mfangano Islands have been the focus of research since 2009 (Tryon et al., 2010Faith et al., 2011Faith et al., , 2012Faith et al., , 2014Van Plantinga, 2011;Jenkins et al., 2017;Blegen et al., in press). More recently, this research has expanded to include the deposits around the region known as Karungu ∼40 km to the south near the town of Sori (Figure 1; Beverly et al., 2015a,b;Blegen et al., 2015;Faith et al., 2015). ...
The impact of changing environments on the evolution and dispersal of Homo sapiens is highly debated, but few data are available from equatorial Africa. Lake Victoria is the largest freshwater lake in the tropics and is currently a biogeographic barrier between the eastern and western branches of the East African Rift. The lake has previously desiccated at ~17 ka and again at ~15 ka, but little is known from this region prior to the Last Glacial Maximum. The Pleistocene terrestrial deposits on the northeast coast of Lake Victoria (94–36 ka) are ideal for paleoenvironmental reconstructions where volcaniclastic deposits (tuffs), fluvial deposits, tufa, and paleosols are exposed, which can be used to reconstruct Critical Zones (CZ) of the past (paleo-CZs). The paleo-CZ is a holistic concept that reconstructs the entire landscape using geologic records of the atmosphere, hydrosphere, lithosphere, biosphere, and pedosphere (the focus of this study). New paleosol-based mean annual precipitation (MAP) proxies from Karungu, Rusinga Island, and Mfangano Island indicate an average MAP of 750 ± 108 mm year−1 (CALMAG), 800 ± 182 mm year−1 (CIA-K), and 1,010 ± 228 mm year−1 (PPM1.0) with no statistical difference throughout the 11 m thick sequence. This corresponds to between 54 and 72% of modern precipitation. Tephras bracketing these paleosols have been correlated across seven sites, and sample a regional paleo-CZ across a ~55 km transect along the eastern shoreline of the modern lake. Given the sensitivity of Lake Victoria to precipitation, it is likely that the lake was significantly smaller than modern between 94 and 36 ka. This would have removed a major barrier for the movement of fauna (including early modern humans) and provided a dispersal corridor across the equator and between the rifts. It is also consistent with the associated fossil faunal assemblage indicative of semi-arid grasslands. During the Late Pleistocene, the combined geologic and paleontological evidence suggests a seasonally dry, open grassland environment for the Lake Victoria region that is significantly drier than today, which may have facilitated human and faunal dispersals across equatorial East Africa.
... Sparse artifacts and abundant fauna from open-air sites on Rusinga Island, Kenya, highlight the association of MSA humans with a diverse and arid-adapted ungulate community (Tryon et al., 2010(Tryon et al., , 2012Faith et al., 2011Faith et al., , 2013Faith et al., , 2014Faith et al., , 2015Faith et al., , 2016Tryon and Faith, 2013;Blegen et al., 2015;Beverly et al., 2015a, b;Garrett et al., 2015). The Wakondo locality is one of three main Pleistocene collecting areas on Rusinga, and lies on the southeastern slope of the island (UTM: 36M 0630458, 9953261),~20 m above the modern lake level of Lake Victoria ( Fig. 1 A and B). ...
The foraging behaviors of Middle Stone Age (MSA) early modern humans have largely been based on evidence from well-stratified cave sites in South Africa. Whereas these sites have provided an abundance of data for behavioral reconstruction that are unmatched elsewhere in Africa, they are unlikely to preserve evidence of the diversity of foraging strategies employed by MSA hunters who lived in a variety of ecological and landscape settings across the African continent. Here we describe the results of recent excavations at the open-air site of Bovid Hill at Wakondo, Rusinga Island, Kenya, which yielded 24 in situ MSA artifacts within an assemblage of bones comprised exclusively of the extinct alcelaphin bovid Rusingoryx atopocranion. The excavated faunal assemblage is characterized by a prime-age-dominated mortality profile and includes cut-marked specimens and an associated MSA Levallois blade-based artifact industry recovered from a channel deposit dated to 68 ± 5 ka by optically stimulated lumines-cence. Taphonomic, geologic, and faunal evidence points to mass exploitation of Rusingoryx by humans at Bovid Hill, which likely represents an initial processing site that was altered post-depositionally by fluvial processes. This site highlights the importance of rivers and streams for mass procurement in an open and seasonal landscape, and provides important new insights into MSA behavioral variability with respect to environmental conditions, site function, and tactical foraging strategies in eastern Africa. Bovid Hill thus joins a growing number of MSA and Middle Paleolithic localities that are suggestive of tactical hunting behaviors and mass capture of gregarious ungulate prey.
... Several of the genera identified from the Luangwa Valley contain extinct as well as extant species, and examples of the latter are known from other southern African Middle Pleistocene localities. Aepyceros includes a South African form, A. helmoedi (Brink et al., 2012), and a hypsodont unnamed species from Kenya (Faith et al., 2014). Several unnamed, potentially new Alcelaphini species have been noted at Middle Pleistocene sites (Klein et al., 2007;de Ruiter et al., 2008;Faith et al., 2011). ...
This paper describes a large collection of Quaternary fossil fauna from the Luangwa Rift Valley, Zambia. Stone Age artefacts have been recovered from stratified fluvial contexts, but no in situ fossil faunas have yet been recovered. We report on 500 fossil specimens collected from the surface of point bars exposed seasonally along the banks of the main Luangwa River channel. We used non-destructive X-ray fluorescence analysis of the fossils' chemical signatures to determine whether they derive from one or many primary contexts, and the relationship between chemical signature and state of preservation. Specimens are identified to taxon (genus) to reconstruct palaeoenvironments and biochronology. A relatively wide range of taxa is identified, including a fossil hominin talus, described here. None of the fossils is positively attributable to extinct species, except a femur of an extinct Theropithecus reported in 2003. Although no additional extinct taxa were identified, some of the remains were attributable to genera that are not currently found in this region. The results suggest that most of the assemblage derives from sediments which are Middle Pleistocene or later, and that past environments in the Luangwa Valley may have differed from the habitat availability found today.
... Understanding how early human populations responded to such changes via geographic, demographic, or behavioral shifts are central goals of paleoanthropology (Barham and Mitchell, 2008;d'Errico and Stringer, 2011;Blome et al., 2012). While fieldwork in southern and western Kenya has greatly expanded our knowledge of paleoenvironments during arid phases of the Late Pleistocene (Marean and Gifford-Gonzalez, 1991;Marean, 1992aMarean, , 1992bFaith et al., 2013Faith et al., , 2014Faith et al., , 2015Tryon and Faith, 2013;Tryon et al., 2010Tryon et al., , 2014Tryon et al., , 2015, the paucity of paleoenvironmental data for humid intervals confounds our ability to address these questions. ...
East Africa has produced the earliest record of Homo sapiens ~200ka and a punctuated record of Middle Stone Age and Later Stone Age behaviors. We lack, however, a detailed late Quaternary paleoenvironmental record for the region, particularly during humid periods. Without a regional record, hypotheses about the evolution and ecology of early Homo sapiens in East Africa remain vague and untestable. The Kibish Formation of southern Ethiopia presents a long, albeit punctuated, record of late Middle Pleistocene to Holocene faunal change in East Africa, which was deposited during humid periods. Here, we present oxygen and carbon stable isotope data of the Kibish ungulates and test whether there are environmental changes within the Kibish Formation. Significant differences in δ18O enamel isotopes are consistent with more humid conditions during the Holocene-age Member IV (~13-4ka) than either Pleistocene-age Member I (~196ka) or Member III (~104ka). Mesowear data document a shift toward more attritional wear among grazers in Member IV and are correlated with more depleted δ18O enamel values, suggesting that the wear pattern shift is linked to the onset of more humid conditions during the Holocene. δ13C enamel values show subtle variations through time, but do not suggest any major changes in diets. We propose that the paleoenvironmental differences evident in Member IV, based on δ18O enamel values, mesowear, and bovid abundances, may be explained by cooler and wetter conditions at the beginning of the Holocene in the lower Omo Valley. The evidence suggesting that the Holocene humid phase is more pronounced than earlier humid phases may explain why arid-adapted grassland ungulates became extinct in East Africa by the Pleistocene-Holocene transition, but persisted through previous humid phases of the late Quaternary.
... Individuals from extinct taxa account for >50% of the large mammals (>5 kg), and include the only reported Late Pleistocene East African occurrences of a suite of extinct taxa, including the bovids Megalotragus sp., Rusingoryx atopocranion, an unnamed impala (Aepyceros sp. nov.), the suid Kolpochoerus sp. and the aardvark Orycteropus crassidens (Lehmann, 2009;Faith, 2014;Faith et al., 2014). At present, much of our fossil sample consists of surface collected specimens. ...
Late Pleistocene sedimentary, biogeochemical, and fossil data from the Lake Victoria basin (the largest lake in Africa) suggest that its reduction or desiccation during periods of increased aridity repeatedly facilitated the dispersal of C4 grassland ecosystems across the basin. Archaeological evidence from Middle Stone Age and Later Stone Age sites suggest that human groups diffused into the basin during intervals of declining lake levels, likely tracking the movement of the dense and predictable resources of shoreline environments, as well as the dense but less predictable C4 grass grazing herbivores. Repeated cycles of lake expansion and contraction provide a push–pull mechanism for the isolation and combination of populations in Equatorial Africa that may contribute to the Late Pleistocene human biological variability suggested by the fossil and genetic records. Latitudinal differences in the timing of environmental change between the Lake Victoria basin and surrounding regions may have promoted movements across, within, and possibly out of Africa.
... These beds are discontinuously exposed over an area of~40 km 2 and are up to 10.5 m in thickness, overlying eroded topography of Miocene bedrock (Pickford, 1984). The Pleistocene deposits are best exposed at the localities of Kisaaka, Aringo, Aoch Nyasaya and Obware (Figs. 4e6;Faith et al., 2014), with the most extensive and thickest exposures at Kisaaka (Figs. 3 and 4) (Beverly et al., in press;Faith et al., 2015). The deposits at Karungu are comprised of fine grained siltstone and mudstone beds that have been pedogenically modified into paleo-Vertisols and paleo-Inceptisols, conglomeratic beds that represent fluvial channels, variably reworked tephra, and tufas deposited by local springs (Beverly et al., in press;Faith et al., 2015). ...
... These beds are discontinuously exposed over an area of~40 km 2 and are up to 10.5 m in thickness, overlying eroded topography of Miocene bedrock (Pickford, 1984). The Pleistocene deposits are best exposed at the localities of Kisaaka, Aringo, Aoch Nyasaya and Obware (Figs. 4e6;Faith et al., 2014), with the most extensive and thickest exposures at Kisaaka (Figs. 3 and 4) (Beverly et al., in press;Faith et al., 2015). The deposits at Karungu are comprised of fine grained siltstone and mudstone beds that have been pedogenically modified into paleo-Vertisols and paleo-Inceptisols, conglomeratic beds that represent fluvial channels, variably reworked tephra, and tufas deposited by local springs (Beverly et al., in press;Faith et al., 2015). ...
The tephrostratigraphic framework for Pliocene and Early Pleistocene paleoanthropological sites in East Africa has been well established through nearly 50 years of research, but a similarly comprehensive framework is lacking for the Middle and particularly the Late Pleistocene. We provide the first detailed regional record of Late Pleistocene tephra deposits associated with artifacts or fossils from the Lake Victoria basin of western Kenya. Correlations of Late Pleistocene distal tephra deposits from the Wasiriya beds on Rusinga Island, the Waware beds on Mfangano Island and deposits near Karungu, mainland Kenya, are based on field stratigraphy coupled with 916 electron microprobe analyses of eleven major and minor element oxides from 50 samples. At least eight distinct distal tephra deposits are distinguished, four of which are found at multiple localities spanning >60 km over an approximately north to south transect. New optically stimulated luminescence dates help to constrain the Late Pleistocene depositional ages of these deposits. Our correlation and characterization of volcaniclastic deposits expand and refine the current stratigraphy of the eastern Lake Victoria basin. This provides the basis for relating fossil- and artifact-bearing sediments and a framework for ongoing geological, archaeological and paleontological studies of Late Pleistocene East Africa, a crucial time period for human evolution and dispersal within and out of Africa.
The Lake Victoria basin of Equatorial Africa was formed as a central depression between the eastern and western branches of the East African Rift System (EARS). Lake Victoria itself, at 68,800 km2, has the largest surface area of freshwater of any lake in Africa. It is also a major source for the White Nile, a waterway that connects the central and northern portions of the continent. On geological timescales, Lake Victoria is ephemeral, and at various intervals during the Pleistocene it has dried up, in the process replaced by more open, grassy habitats similar to those found in the Serengeti today. These contrasting conditions in the past serve to underscore archaeological and biogeographic evidence for the social and environmental dynamism of the region, dynamism that likely included periodic intervals of the expansion and contraction of the ranges of plant and animal populations that included early Homo sapiens.
Zooarchaeology is the study of animal bones from archaeological sites. Africa has the longest archaeological record in the world, potentially extending into the Pliocene and spanning the entire Pleistocene epoch. However, in comparison to other regions of Eurasia, this extended chronology in Africa has not translated to larger numbers of identified sites, more even distribution of sites, or more abundant faunal data. Here, we describe the methods commonly used by zooarchaeologists to analyze faunal assemblages, followed by a summary of general faunal taxonomic patterns across the continent. We then compile data from all Pleistocene zooarchaeological assemblages in Africa for which there is a published record of the site in a peer-reviewed journal or book as of the end of 2020. This facilitates a region-by-region discussion of trends in readily available zooarchaeological data and evaluation of their potential to inform about past environments and hominin interactions with faunal communities. We note that faunal remains exclusively recovered from surface contexts are not included as it is not possible to ascertain their chronological coherence or certainty of association.The reviewed faunal assemblages (N = 409) display a great deal of variability in composition, size, and distribution patterns, largely driven by a combination of depositional factors (in which fossils are likely to preserve in stable depositional settings) and research emphasis (in which archaeologists have worked most intensively versus those less explored). This variability is also tied to the individual regional histories of archaeological infrastructure development, which support repositories and training centers in the form of museums and universities. Most of the faunal data come from eastern, southern, and northern Africa and the Horn, which have rich assemblages from both open-air and cave/rock shelter sites that span the Pleistocene. In contrast, most archaeofaunas from other regions derive from sheltered sites that emphasize the preservation of the Late Pleistocene part of the record and tend to comprise many more fragments. In spite of significant geographic and chronological bias, research on Pleistocene faunal assemblages from Africa has made substantial contributions to understanding early human–animal interactions, developing zooarchaeological methods, and reconstructing ancient environments. There is significant potential for future research to continue doing so, both by revisiting the existing assemblages with new methods and by excavating new ones.
The site frequency spectrum (SFS) is an important summary statistic in population genetics used for inference on demographic history and selection. However, estimation of the SFS from called genotypes introduce bias when working with low-coverage sequencing data. Methods exist for addressing this issue, but sometimes suffer from two problems. First, they can have very high computational demands, to the point that it may not be possible to run estimation for genome-scale data. Second, existing methods are prone to overfitting, especially for multi-dimensional SFS estimation. In this article, we present a stochastic expectation-maximisation algorithm for inferring the SFS from NGS data that addresses these challenges. We show that this algorithm greatly reduces runtime and enables estimation with constant, trivial RAM usage. Further, the algorithm reduces overfitting and thereby improves downstream inference. An implementation is available at github.com/malthesr/winsfs.
Current models of early hominin biological and cultural evolution are shaped almost entirely by the data accumulated from the East African Rift System (EARS) over the last decades. In contrast, little is known about the archaeological record from the high-elevation regions on either side of the Rift. Melka Wakena is a newly discovered site-complex on the Southeastern Ethiopian Highlands (SEH) (>2300 m above mean sea level) just east of the central sector of the Main Ethiopian Rift (MER), where eight archaeological and two paleontological localities were discovered to date. Nine archaeological horizons from three localities were tested so far, all dated to the second half of the early Pleistocene (~1.6 to >0.7 Ma). All the lithic assemblages belong to the Acheulian technocomplex. Here we report on geochronological, stratigraphic, paleontological and lithic technological aspects of the tested localities and contextualize them in the broader framework of hominin cultural evolution in eastern Africa. Findings from Melka Wakena, assessed against the backdrop of the few other highland sites (Melka Kunture and Gadeb), support a scenario of expansion rather than dispersal from the Rift to the highlands. When considered in the context of the Rift-highlands interface, results of the first-phase research at Melka Wakena help to parse existing general models into archaeologically testable hypotheses and demonstrate the site's potential to contribute to research of early prehistory and to understanding the dynamics of early Pleis-tocene hominin populations in eastern Africa.
We report on the Late Pleistocene (36-12 ka) mammals from Kibogo in the Nyanza Rift of western Kenya, providing (1) a systematic description of the mammal remains, (2) an assessment of their paleoenvironmental implications, and (3) an analysis of the biogeographic implications of non-analog species associations. Kibogo has yielded one of the largest paleontological assemblages from the Late Pleistocene of eastern Africa, and it is dominated by grassland ungulates (e.g., equids and alcelaphin antelopes), including an assortment of extralimital (e.g., Equus grevyi, Ceratotherium simum, Redunca arundinum) and extinct species (Syncerus antiquus, Damaliscus hypsodon, Megalotragus sp.). The composition of the fauna, in conjunction with the soils and topography of the region, indicate the local presence of edaphic grassland situated within a broader environment that was substantially grassier and likely drier than at present. In contrast to non-analog faunas from higher latitudes (e.g., North America and western Eurasia), the climatic niches of non-analog species associations strongly overlap, indicating that non-analog climate regimes during the Late Pleistocene of eastern Africa are not necessary to account for the former association of presently allopatric species. The Kibogo faunas add to a growing body of evidence implying that the composition of present-day African herbivore communities is distinct from those of the geologically recent past.
Here we report tephra correlations, lithic artifacts, obsidian sourcing data, and fauna from nine Late Pleistocene localities of the eastern Lake Victoria basin of western Kenya, as well as new excavations from the 49-36 ka site of Nyamita Main on Rusinga Island. The Late Pleistocene of Africa is an important period for the evolution and dispersals of Homo sapiens. A conspicuous behavioral feature of this period is the replacement of Middle Stone Age (MSA) technologies by Later Stone Age (LSA) technologies. Current research shows this process is complex with the LSA appearing and the MSA disappearing at different times in different places across Africa. Accounting for this pattern requires a precise chronology, detailed evidence of past human behavior and environmental reconstructions of the appropriate scale. Data presented here provide this detail. Tephra correlations improve the regional chronology and expand the lateral area of Late Pleistocene eastern Lake Victoria basin exposures from ~650km 2 to >2500km 2. Lithic artifacts show MSA technology is present younger than 36 ka in western Kenya, 25-35 kyr younger than the first appearance of early LSA technology elsewhere in equatorial East Africa. Obsid-ian sourcing data presented here shows the use of the same raw material sources by MSA and LSA populations through long periods of time from >100 ka through <36 ka. The methods employed here provide the temporal resolution and appropriate geographic scale to address modern human behavioral evolution.
Ancestors of mammals separated from reptiles and birds during the Carboniferous. Early members of the mammalian lineage, called “mammal-like reptiles” as they lack mammalian specializations, flourished during the Permian. Survivors of the Permian-Triassic boundary mass extinction progressively developed mammalian characters. The basic characteristic whereby the Mammalia are defined is the structure of the middle ear. In “reptiles”, including mammal-like reptiles, the lower jaw consists of several bones, one of which, the dentary, contains the teeth, another, the articular, forms a joint with a bone called the quadrate in the cranium, and there is only a single bone, the stapes, in the middle ear. Through the Miocene and Pliocene, mammalian lineages seem to have undergone diversification and extinction at rates that had characterised most of the Cenozoic. It was only the Pleistocene that saw elevated extinction rates, mainly affecting large mammals. The human lineage may have separated from that of chimpanzees some 6–7 million years ago, but about 4 million years ago there was an episode of interbreeding between the two lineages, leaving humans with an X chromosome that is markedly more chimpanzee-like than the rest of the genome. Comparative morphology and DNA analysis agree chimpanzeesare the closest living relatives of humans, followed by gorillas, then orangutans and then gibbons. Most molecular clock calculations indicate that the human and chimpanzee lineages separated some 6 million years ago. Sahelanthropus tchadensis is plausibly promoted as the earliest member of the Hominini.
Significance
Many have argued that major developments in mammalian (including human) evolution were timed with large and sudden changes to Earth’s climate. Our new analyses of the eastern African Plio-Pleistocene mammalian fossil record indicate that most species originations and extinctions took place continuously and gradually. This means that evolution was not clustered in short intervals, nor were sudden global climatic changes the main cause of species extinction in the past. Global climate may have influenced longer-term (million year) evolutionary trends, but local environmental changes and species interactions were more important at shorter (100,000 y) time scales.
In growing numbers, archeologists are specializing in the analysis of excavated animal bones as clues to the environment and behavior of ancient peoples. This pathbreaking work provides a detailed discussion of the outstanding issues and methods of bone studies that will interest zooarcheologists as well as paleontologists who focus on reconstructing ecologies from bones. Because large samples of bones from archeological sites require tedious and time-consuming analysis, the authors also offer a set of computer programs that will greatly simplify the bone specialist's job. After setting forth the interpretive framework that governs their use of numbers in faunal analysis, Richard G. Klein and Kathryn Cruz-Uribe survey various measures of taxonomic abundance, review methods for estimating the sex and age composition of a fossil species sample, and then give examples to show how these measures and sex/age profiles can provide useful information about the past. In the second part of their book, the authors present the computer programs used to calculate and analyze each numerical measure or count discussed in the earlier chapters. These elegant and original programs, written in BASIC, can easily be used by anyone with a microcomputer or with access to large mainframe computers.
Palaeontology typically relies on fossil studies, in particular morphological differences, to reconstruct and interpret patterns of vertebrate evolution. However, genetic studies of population histories of extant species provide data about past population events (e.g. local extinctions, recolonisations) which are equally relevant to palaeontological questions. This study used morphological traits to evaluate a hypothesis based on genetic evidence that southern African impala (Aepyceros melampus) are the founder population for all other living African impala populations, after an eastern African extirpation event dating to around 200 000 years ago. Measurements of three horn metrics and the presence or absence of a particular dental trait were compared across four regional impala samples. Eastern African impala possess a unique combination of larger horns and a significantly higher occurrence of entostyles when compared to other impala populations. These traits are likely to have characterised a small group of founding impala which recolonised this region. This pattern appears consistent with the genetic evidence that a subset of the southern African impala gave rise to the eastern African populations. Other species with complex population histories, such as wildebeest, eland, topi and hartebeest may also therefore be expected to express variation in certain morphological traits in the fossil record because of similar patterns of recolonisations. The process of local extinction and subsequent repopulation over shorter timescales (10(2) - 10(3) years) may pass unnoticed in the fossil record, and lineages may appear uninterrupted. Instead, greater morphological variation within a species may be observed, which may be misinterpreted as reflecting a speciation event, or ecophenotypic variation. Combining data from genetic studies and palaeontology may provide further clues as to how faunal dispersals within Africa shaped the morphological variation in the fossil record, and how to best interpret such differences.
Members of the African Bovidae exhibit dietary resource partitioning, which presumably allows coexistence of many species with herbivorous diets. Levels of resource partitioning based on diet include primary food preference, habitat preference, and feeding-height preference. Morphological correlates of these levels of resource partitioning were sought in the skull and vertebral column of 33 bovid species. A quantitative morphometric study of the mandible, skull, and thoracic vertebrae in a large sample of bovids (n > 700) explores these correlates using video-image analysis. Results of this study indicate that many significant morphological differences exist among bovids that have a diet of either grass, dicots, or some combination of these two primary resources. In addition, some variables significantly distinguished bovids with different habitat and feeding-height preferences. These morphological correlates crossed taxonomic boundaries and, in many cases, were related to the structural properties of the herbivorous diet.
We provide stable carbon isotope data from 37 species of African bovids to document dietary preferences for C3 browse (or fruits) or C4 grass. These data provide a quantitative measure of the fraction of C4 grass in bovid diets, can be applied on regional to local scales, can be derived from tooth enamel and hair or other tissues, and permit the diets of bovids to be considered in the context of a grazer - browser continuum. We recognize hypergrazers (>95% C4 grass), grazers (70-95% C4 grass), mixed feeders (>30% C4 grass and >30% C3 browse), browsers (70-95% C3 browse), and hyperbrowsers or frugivores (>95% C3 browse or fruit). Our results suggest that, of the extant East African Bovidae, impala (Aepyceros melampus), Thomson's gazelle (Gazella thomsonii), and oribi (Ourebia ourebi) can be construed as mixed feeders. Dietary estimates based on stable isotope analysis are in broad agreement with other measures of diet such as hypsodonty index, mass relationships, and wear scratches on enamel.
Surveys and excavations in 2009�2011 recovered fossil and artefact assemblages
from late Pleistocene sediments on Rusinga and Mfangano islands (Lake Victoria,
Kenya). Radiometric age estimates suggest that the Rusinga material dates to
between 100 and 33 kya, whereas that from Mfangano may date to ]35 kya. The
preservation of a large and diverse suite of vertebrate fossils is unusual for Pleistocene
sites in the Lake Victoria region and the composition of the faunal assemblages from
both islands strongly suggest an open, arid, grassland setting very different from that
found inwesternKenya today.Middle Stone Age(MSA) artefacts fromRusinga and
possible Later Stone Age (LSA) or MSA/LSA assemblages from Mfangano are
distinct from Lupemban MSA sites characteristic of the Lake Victoria region and
instead share a number of typological and technological features with late
Pleistocene sites from open grassland settings in the East African Rift System. This
highlights the complex roles that shifting environments, as well as temporal change,
may have played in the development of regional variation among EquatorialAfrican
artefact assemblages in the Pleistocene.
Keywords: Middle Stone Age; Later Stone Age; Quaternary; aridity; Lake Victoria
Stable carbon isotope data (d13C) from feces of mixed-feeding impala Aepyceros melampus living in South Africa’s Kruger National Park are used to study dietary variations across a variety of spatio-temporal scales. We test hypotheses that ungulate dietary variations are related to relative proportions of woody plants:grass in surrounding landscapes, and that rainfall regulates ungulate ecology. Results show that impala diets traverse the browser/grazer spectrum, varying widely in proportions of browse: grass consumed at monthly, seasonal, annual, and regional scales. Impala living in open savanna and grassland landscapes generally eat more grass than their counterparts in savanna woodlands, but this differentiation is not consistent at all temporal scales. In one densely wooded region, Punda Maria in the far north of Kruger, impala consume more grass than elsewhere in the Park. Impala in riparian areas eat lower quantities of grass than in other habitat types, especially during the dry periods when spatial differences in diet are more pronounced. Hence assumptions that ungulate feeding ecology reflects the woody plant:grass composition of their habitats are not supported by our data, nor was a relationship between diet and rainfall detected. The results do support a model of increased grass consumption with increasing protein content of available grasses. Fecal %N data show minimal variations across space and time, suggesting that impala are selective feeders that choose foods, whether browse or grass, in order to maintain optimal levels of diet quality. Given these results, it is more likely that detailed models of food selection, available through optimal foraging theory, can better describe ecological variation
We revise here the entire collection of Bovidae from the Pliocene Hadar Formation collected at Hadar and Ledi-Geraru, Lower Awash, Ethiopia. Some additions are provided to previously published descriptions, and other forms are described. The complete list includes 28 species, but is dominated by a new species of impala, Aepyceros datoadeni, a kob that we assign to Kobus oricornus, although it belongs to a type distinct from the Omo one, a lineage of alcelaphins that is poorly known elsewhere, Damalborea, and the bovin Ugandax. We also describe a new gazelle, Gazella harmonae, with very peculiar features, including long spiraled horn cores. Changes in the bovid fauna can be detected both within individual lineages, and in the composition of the assemblage. Impala and bovins far outnumber the reduncins in the lower part of the sequence (Basal and Sidi Hakoma members, from ca. 3.8 to 3.2 Ma), but relative abundances become more equal higher up. Biometric changes do occur in the Ugandax and Aepyceros lineages, but are not significant in other lineages. The major evolutionary events occur in the KH1 or KH1/KH2 transition, ca 3.1−3.0 Ma, with appearance of a third tragelaphin species, of a very small alcelaphin and of a large Aepyceros, and the likely disappearance of K. oricornus.
The paleoenvironmental context of plant and animal species evolution (including glacial migrations and population separations) is based on a very patchy and incomplete paleo-phytogeographic record. It was our objective, therefore, to provide an additional source for paleovegetation comparison by presenting simulations from a state-of-the-art fully coupled earth system model (HadCM3LC). We simulated potential paleovegetation distributions following pre-Industrial and last glacial maximum (LGM) climate forcing for the continent of Africa. Our LGM simulations indicate that tropical broadleaf forest was not severely displaced by expanding grasslands within central Africa, although the outer extent of closed forest decreases, particularly in the north. Our simulations indicate that the structure of glacial forests may have been much different from today, in that LGM simulations indicate that forests were likely characterized by lower leaf area indexes, lower tree heights and lower vegetation carbon content. On the other hand, warmer interglacial climate (like our pre-Industrial climate scenario) results in simulated expansion of tropical forest from coast to coast across central Africa that we postulate could have acted as a barrier to plant and animal species migrations. We suggest that our modeling experiments have implications for the interpretation of phylogenetic data, including that of our own species, Homo sapiens sapiens.
Although bovids have been studied for decades, debate still exists about their diets. To address this problem, we examined bovid dietary ecology through analysis of stable carbon isotopes. We analyzed tooth enamel, bone collagen, and hair from 312 individual bovids, representing 27 species from southern Africa. Although dietary information from the lit-erature is usually supported by this technique, our results and the literature are sometimes highly divergent. For instance, our results indicate that Taurotragus oryx and Raphicerus campestris eat less grass than is widely believed. Furthermore, contrary to most theoretical expectations, our data indicate no relationship between body size and percentage of mono-cots consumed by southern African Bovidae. Although many researchers have abandoned the idea that bovid soft-tissue anatomy is strongly indicative of diet, we demonstrate a strong relationship between the percentage of grass in a bovid's diet and several hard-tissue craniodental indices.
Pollen data from 18,000 14C yr bp were compiled in order to reconstruct biome distributions at the last glacial maximum in southern Europe and Africa. Biome reconstructions were made using the objective biomization method applied to pollen counts using a complete list of dryland taxa wherever possible. Consistent and major differences from present-day biomes are shown.
Forest and xerophytic woods/scrub were replaced by steppe, both in the Mediterranean region and in southern Africa, except in south-western Cape Province where fynbos (xerophytic scrub) persisted.
Sites in the tropical highlands, characterized today by evergreen forest, were dominated by steppe and/or xerophytic vegetation (cf. today’s Ericaceous belt and Afroalpine grassland) at the last glacial maximum.
Available data from the tropical lowlands are sparse but suggest that the modern tropical rain forest was largely replaced by tropical seasonal forest while the modern seasonal or dry forests were encroached on by savanna or steppe. Montane forest elements descended to lower elevations than today.
Lingering debate among evolutionary biologists over whether or not Lake Victoria dried out during the late Pleistocene focuses
on perceived conflicts between biological and geological evidence for the age of its endemic species. This article reviews
and updates the geophysical and paleoecological evidence for lake-wide desiccation and describes the environmental conditions
that aquatic species likely experienced during the low stand. Lake Victoria was at its lowest between 18,000 and 14,000 calendar
years ago, and it dried out at least once during that time. There is no evidence of remnant ponds or marshes persisting within
the desiccated basin. If such features existed, then they would have been small, shallow, turbid, and/or saline, and therefore
markedly different from the lake to which today’s species are adapted. The existence of Lake Victoria’s diverse endemic biota
must be reconciled with the incontrovertible geophysical and paleoecological evidence of a ca. 15,000year age for the lake,
and not vice versa.
Bovidae contain the cattle, sheep, goats, and antelopes. The word “antelope” is used for bovids outside Europe, mostly in Africa, or not domesticated before Carl Linnaeus' lifetime. It does not correspond with a formal taxonomic category. Most phylogenies postulate bovids being closer to cervids than to giraffids. Unlike the cervoid Moschus in relation to Cervidae, there is no living hornless pecoran thought to be a bovoid (member of a superfamily Bovoidea including Bovidae and any related families, the latter as yet unknown). In Eurasia, tiny bovid-like dental remains are known well back to the early Oligocene of Mongolia, but nothing is known of pre-Miocene ruminants in Africa. Pecorans such as Walangania, Propalaeoryx, and Namibiomeryx do appear in the early Miocene, and the last has been claimed to be a bovid. Subfamilies of Bovidae include Hypsodontinae, Bovinae, Antilopinae, Reduncinae, Oiocerinae, Hippotraginae, and Caprinae. This chapter discusses the overall classification of Bovidae and their evolutionary relationships.
This paper describes the fluctuations of Lakes Victoria, Stefanie, Turkana and Naivasha over the last two centuries. A chronology of Lake Victoria back to 700 A.D. is also developed. These chronologies are based mainly on oral traditions of the local peoples, as described in various historical sources, and on reports of European visitors, settlers and explorers. In some cases actual historical levels have been reported. The historical fluctuations are meshed with the modern record to provide a picture of the fluctuations in lake levels until the late twentieth century.
The chronologies for Victoria and Stefanie contain much new material, permitting higher temporal resolution and better quantitative assessments, as well as extension of chronologies to the beginning of the 19th century. For Lakes Turkana and Naivasha, chronologies published by other authors are expanded and compared with those for Victoria, Stefanie and other African lakes. A long term chronology for Lake Victoria is developed using the record of the summer Nile flow.
These lakes show remarkably similar trends. The most important of these trends are low levels during the first half of the 19th century, very high stands in the last decades of the 19th century, and around the turn of the century a rapid fall to 20th century levels. The lakes returned to relatively high stands in the 1960s, but these generally ended in the 1970s.
Sisters of a sister-group are taxa that share a more recent common ancestry with each other than either does with any other taxon. One of the most interesting aspects of evolution concerns the very different histories in terms of morphological diversification that such sistertaxa often have. Elsewhere I have suggested that the causes of different kinds of evolution may be especially well studied in low-ranking sister-groups that include a fossil record plus extant survivors, and that are still in a phase of evolutionary radiation (Vrba 1980a). The bovid tribes Alcelaphini (blesbuck—hartebeest—wilde—beest group) and Aepycerotini (impalas) provide such a case.
Open-air archaeological sites record only a small fraction of the behavioral traces of mobile forager populations. Whereas caves and rockshelters were often occupied at least in part for protection from the elements, the reasons why human foragers occupied other places on the landscape (however briefly) are varied and not always readily recoverable. We develop a framework for interpreting human use of the landscape and modeling occupation of open-air sites using the archaeological and paleoenvironmental record of Middle Stone Age (MSA) sites from Rusinga and Mfangano Islands, located near the eastern margin of Lake Victoria. Paleoenvironmental reconstructions using fossil faunas suggest an arid grassland setting unlike the present. Paleoecological modeling of the habitats of extant and extinct bovids, combined with GIS-based reconstructions of lake level change, indicate that human occupation of these sites coincided with substantial declines in the level of Lake Victoria. During this time, both Rusinga and Mfangano would have been connected to the mainland and represented local topographic highs within an extensive grassland. Geological, ecological, and ethnobotanical observations suggest that these topographic high points would likely have been important sources of stone raw material, fresh water, and a variety of plant resources for food, fuel, and other purposes. In contrast, the grassy lowland plains were probably exploited primarily as a source of large game, which included numerous species of large gregarious grazers, several of which may have followed now extinct migration routes.
Quality of food selected by free-roaming male impala Aepyceros melampus was studied on sites originating from gabbro and granite formations. Species surveys done during the trial showed the composition of the grass layer on gabbro to consist of more palatable species with probable associated advantages in nutritive value. Samples collected from oesophageal fistulae were analysed for chemical constituents, in vitro digestibility (IVDOM) and botanical composition, and samples obtained from rumen fistulae for volatile fatty acids (VFA) and ammonia (NH3). Differences in quality parameters between the rainy and dry seasons were marked, whereas differences between habitats (gabbro vs granite) were mostly not significant. Intake did not differ significantly either. In terms of percentage grass and browse selected, habitat differences were not significant. In the rainy season grass constituted 90% of the diet, while browse increased to 35% of intake during the dry season. We conclude that impala optimize quality of diet selected irrespective of the plant composition, provided sufficient material is available.
A major step in mammalian evolution was the shift amongst many herbivorous clades from a browsing diet of leaves to a grazing diet of grasses. This was associated with (1) major cooling and increasing continentality and the enormous spread of grasslands in most continents, replacing closed and open forests, and (2) hypsodonty, the possession of high-crowned teeth. Hypsodonty is traditionally linked with eating grass because of the contained phytoliths, silica-rich granules, which are presumed to wear away mammalian dental tissues. However, we present evidence from the Great Plains of North America that the origins of hypsodonty in different clades of ungulates (hoofed mammals) and Glires (rodents and lagomorphs) were substantially out of synchrony with the great spread of grasslands, 26–22 Myr ago (latest Oligocene/earliest Miocene). Moderate hypsodonty was acquired by some Oligocene artiodactyls and several rodent families (mainly burrowers) at least 7 Myr earlier. Highly hypsodont ungulates and hypselodont (= ever-growing cheek teeth) rodents post-date the spread of grasslands by 4 to 9 Myr. Lagomorphs follow a different trend, with hypselodont forms present from near the Eocene–Oligocene boundary. These results indicate that hypsodonty was not a simple adaptation for eating grasses, and may have originated in some clades to counteract the ingestion of grit and soil.
The middle Pleistocene fossil mammal assemblage from Lainyamok in the southern Kenya rift has previously been considered the oldest (330–392 ka) African mammal community consisting entirely of extant species, with the dominant bovid tentatively attributed to the southern African blesbok (Damaliscus cf. dorcas). We show that the blesbok-like fossils from Lainyamok belong to an extinct species, described here as Damaliscus hypsodon sp. nov. The D. hypsodon hypodigm includes the previously unnamed small alcelaphine material known from late Pleistocene sites elsewhere in Kenya and Tanzania. Its dental anatomy, together with an ecomorphological analysis of its postcrania, indicates that D. hypsodon grazed in open and arid grassland environments. Although Lainyamok is no longer represented entirely by extant species, the absence of species common earlier in the middle Pleistocene of East Africa suggests substantial faunal turnover between 500 and 400 ka. Damaliscus hypsodon persisted in East Africa until the end of the Pleistocene and its extinction can be attributed to a loss of arid grassland environments at the onset of the Holocene. The fossil evidence from southern Kenya suggests that the development of the taxonomically modern large mammal community was a long-term process characterized by the extinction of grazing specialists, with marked turnover occurring between ~ 500 and 400 ka and near the end of the Pleistocene.
Within the last several decades, Grévy's zebra (Equus grevyi) has undergone a massive reduction in geographical range and population size, largely as the result of human impacts. To place its recent decline in a deeper prehistoric context, and to understand the factors mediating its range and abundance over geological time frames, this study examines the fossil history of Grévy's zebra in equatorial East Africa.
Equatorial East Africa.
Presence/absence data for ungulates recovered from fossil sites spanning the last c. 400,000 years in Kenya and Ethiopia were compiled from the literature and from previously unreported palaeontological sites. Associations between Grévy's zebra and other taxa were examined using principal coordinates analysis and non-random species pairs were identified using a Bayesian approach. Changes in rainfall were reconstructed using the average hypsodonty index of ungulate species from fossil assemblages.
Grévy's zebra was common during dry phases of the Pleistocene and was found to the south and west of its historical range, coinciding with an expansion of arid grasslands. At the onset of the Holocene, Grévy's zebra was extirpated from southern Kenya and almost completely disappeared from the fossil record. Grévy's zebra was associated with several specialized grazers that became extinct by the end of the Pleistocene. These extinctions and the decline of Grévy's zebra from the Pleistocene to the Holocene are explained by increased precipitation and the consequent loss of arid grasslands at the Pleistocene–Holocene transition. Grévy's zebra is never associated with domestic livestock, unlike the widespread plains zebra.
Grévy's zebra thrived in equatorial East Africa during periods of the Pleistocene when environmental conditions favoured an expansion of arid grasslands. Environmental change across the Pleistocene–Holocene transition contributed to decreases in the range size and abundance of Grévy's zebra, setting the stage for the anthropogenic decline observed in recent decades. The spread of pastoralists in the middle Holocene may have additionally contributed to its prehistoric decline. Contemporary climate change warrants further consideration in planning for the long-term survival of Grévy's zebra.
Intersexual and seasonal variation in foraging behaviour of impala (Aepyceros melampus), was studied in the Lake Mburo National Park, Uganda. There was a moderate seasonal difference in foraging efficiency (as measured by 'acceptable food abundance'), with a minimum in dry season and a maximum in Rainy season. The variation between sexes was more distinct with a pronounced minimum in time spent browsing of males in early wet season. By distinguishing between feeding time spent grazing and feeding time spent browsing the seasonal variation was confirmed. The proportion of foraging time spent feeding (expressed as 'food ingestion rate') showed an inverse pattern with a maximum in the late dry season (75.5%), decreasing values throughout the Rainy season and a minimum in early dry season (57.8%). Differences between sexes were explained in terms of reproductive demands and seasonal balance in terms of moderate climate throughout the year. Impala foraging patterns in the bimodal tropics (two Rainy seasons) is discussed and compared with unimodal tropics. The findings are matched against current ideas on optimal foraging.
East Africa’s enormous Lake Victoria dried out at the close of the last glacial, but the precise timing and origin of that drying event have not been clarified, largely because of uncertainty regarding core stratigraphy and ancient carbon effects on 14C dates from the lake. New dates and re-examination of evidence from widely distributed cores shows that desiccation occurred some time between 15 900 and 14 200 calendar years BP, and perhaps also ca. 18–17 kyr BP. These lake level minima were briefer than has been previously suggested and were synchronous with pronounced global climate disruptions including North Atlantic ice-rafting Heinrich event 1. Less severe declines occurred during the Older and Younger Dryas intervals. Dansgaard–Oeschger type cooling cycles registered in the GISP2 ice core record tracked major lake level regressions in East Africa and weakenings of Afro-Asian monsoons during the late Quaternary, possibly linking the desiccation of Lake Victoria to century-scale reductions in solar radiation output.
Rusingoryx atopocranion is a poorly known extinct alcelaphine bovid, documented in Pleistocene deposits associated with Middle Stone Age artifacts on Rusinga Island, Kenya. Following its initial description, Rusingoryx was subsumed into Megalotragus, which includes the extinct giant wildebeests, on the basis of its cranial architecture. Renewed investigations of the Pleistocene deposits on Rusinga Island recovered a large sample of Rusingoryx specimens that provide new taxonomic and paleoecological insight. This study (1) reviews the morphological and phylogenetic evidence concerning the taxonomic status of Rusingoryx and (2) evaluates its paleoecology and dietary habits. The morphology and phylogenetic data indicate that Rusingoryx is distinct from Megalotragus; they likely shared a common ancestor in the late Pliocene. Ecomorphology and mesowear analysis point to a specialized grazing adaptation, and its association with arid-adapted ungulates suggests a preference for arid grasslands. The confirmation of Rusingoryx as a valid taxonomic entity, together with the presence of other extinct taxa (including Megalotragus) on Rusinga Island, suggests an increasingly complex pattern of ungulate biogeography and extinctions in the late Quaternary of East Africa. Rusingoryx appears to have been part of an arid-adapted faunal community that potentially persisted in East Africa until the onset of the Holocene.
Aim Previous genetic studies of African savanna ungulates have indicated Pleistocene refugial areas in East and southern Africa, and recent palynological, palaeovegetation and fossil studies have suggested the presence of a long-standing refugium in the south and a mosaic of refugia in the east. Phylogeographic analysis of the common eland antelope, Taurotragus oryx (Bovidae), was used to assess these hypotheses and the existence of genetic signatures of Pleistocene climate change.
Location The sub-Saharan savanna biome of East and southern Africa.
Methods Mitochondrial DNA control-region fragments (414 bp) from 122 individuals of common eland were analysed to elucidate the phylogeography, genetic diversity, spatial population structuring, historical migration and demographic history of the species. The phylogeographic split among major genetic lineages was dated using Bayesian coalescent-based methods and a calibrated fossil root of 1.6 Ma for the split between the common eland and the giant eland, Taurotragus derbianus.
Results Two major phylogeographic lineages comprising East and southern African localities, respectively, were separated by a net nucleotide distance of 4.7%. A third intermediate lineage comprised only three haplotypes, from Zimbabwe in southern Africa. The estimated mutation rate of 0.097 Myr−1 revealed a more recent common ancestor for the eastern lineage (0.21 Ma; 0.07–0.37) than for the southern lineage (0.35 Ma; 0.10–0.62). Compared with the latter, the eastern lineage showed pronounced geographic structuring, lower overall nucleotide diversity, higher population differentiation, and isolation-by-distance among populations.
Main conclusions The data support the hypothesis of Pleistocene refugia occurring in East and southern Africa. In agreement with palynological, palaeovegetation and fossil studies, our data strongly support the presence of a longer-standing population in the south and a mosaic of Pleistocene refugia in the east, verifying the efficacy of genetic tools in addressing such questions. The more recent origin of the common eland inhabiting East Africa could result from colonization following extinction from the region. Only two other dated African ungulate phylogenies have been published, applying different methods, and the similarity of dates obtained from the three distinct approaches indicates a significant event c. 200 ka, which left a strong genetic signature across a range of ungulate taxa.
The phylogeography of the bush habituated African bovid species impala (Aepyceros melampus) and greater kudu (Tragelaphus strepsiceros) is investigated using mitochondrial DNA (mtDNA) markers. Combined analysis of individual lineages, relationships and population genetics suggest a colonization process from Southern Africa toward Eastern regions in the greater kudu. Results are less clear for the impala, although remaining consistent with a similar pattern of historical dispersion. The study reveals a similar pattern, that is a marked divergence of lineages from South-western Africa relative to other regions. This pattern is opposed to previously published findings in other African bovid species. In the impala, the genetically isolated region is consistent with morphology because it is recognized as the subspecies A. m. petersi, the black-faced impala. In contrast, the similar split of South-western mitochondrial lineages was not expected in the greater kudu on the basis of morphology. Both species show a significant population genetic differentiation. Beyond their phylogeographical value, our results should raise conservation concerns about South-western populations of both species. The black-faced impala is categorized as vulnerable and our data show indications of hybridization with common impala A. m. melampus. The previously unrecognized genetic status of the South-western kudus could also imply conservation regulations.
The savannah biome of sub-Saharan Africa harbours the highest diversity of ungulates (hoofed mammals) on Earth. In this review, we compile population genetic data from 19 codistributed ungulate taxa of the savannah biome and find striking concordance in the phylogeographic structuring of species. Data from across taxa reveal distinct regional lineages, which reflect the survival and divergence of populations in isolated savannah refugia during the climatic oscillations of the Pleistocene. Data from taxa across trophic levels suggest distinct savannah refugia were present in West, East, Southern and South-West Africa. Furthermore, differing Pleistocene evolutionary biogeographic scenarios are proposed for East and Southern Africa, supported by palaeoclimatic data and the fossil record. Environmental instability in East Africa facilitated several spatial and temporal refugia and is reflected in the high inter- and intraspecific diversity of the region. In contrast, phylogeographic data suggest a stable, long-standing savannah refuge in the south.
Substantial revisions are made to the account of the Bovidae of the Laetolil Beds and the Upper Ndolanya Beds given in Gentry
(1987). Both beds have 17 or 18 species with a wide range of tribal affiliations. The bovids of the Laetolil Beds are unlike
those in the “Plio-Pleistocene” faunas of Olduvai Gorge and the Shungura and Koobi Fora Formations. Some species are primitive,
others are divergently specialized. Reduncini may well be totally absent, and a few teeth of a larger Cephalophus represent a rarely fossilized tribe. A little-advanced Hippotragus is more abundant than in later faunas. One or two links can be discerned between the bovids in the Upper Ndolanya Beds and
those in the Laetolil Beds, but the differences are more striking. There are signs of a “Plio-Pleistocene” fauna being in
place, and some of its species reach a large size. A new species of Aepyceros is described from the Laetolil Beds and of an alcelaphine from the Upper Ndolanya Beds.
KeywordsMammals-Pliocene-Africa-Laetoli-Descriptions-Taxonomy-Revision
Environmental theories of African faunal evolution state that important evolutionary changes during the Pliocene–Pleistocene interval (the last ca. 5.3 million years) were mediated by changes in African climate or shifts in climate variability. Marine sediment sequences demonstrate that subtropical African climate periodically oscillated between markedly wetter and drier conditions, paced by earth orbital variations, with evidence for step-like (±0.2 Ma) increases in African climate variability and aridity near 2.8 Ma, 1.7 Ma, and 1.0 Ma, coincident with the onset and intensification of high-latitude glacial cycles. Analysis of the best dated and most complete African mammal fossil databases indicates African faunal assemblage and, perhaps, speciation changes during the Pliocene–Pleistocene, suggesting more varied and open habitats at 2.9–2.4 Ma and after 1.8 Ma. These intervals correspond to key junctures in early hominid evolution, including the emergence of our genus Homo. Pliocene–Pleistocene shifts in African climate, vegetation, and faunal assemblages thus appear to be roughly contemporary, although detailed comparisons are hampered by sampling gaps, dating uncertainties, and preservational biases in the fossil record. Further study of possible relations between African faunal and climatic change will benefit from the accelerating pace of important new fossil discoveries, emerging molecular biomarker methods for reconstructing African paleovegetation changes, tephra correlations between terrestrial and marine sequences, as well as continuing collaborations between the paleoclimatic and paleoanthropological communities.
Late Quaternary paleoenvironmental data for East Africa are derived primarily from montane sources and thus we know little about the changing composition of East African savannas. Four archaeological sites at Lukenya Hill in the savanna of the Athi-Kapiti Plains of Kenya that date to the last 40,000 yr preserve a large mammalian fauna. The prehistoric hunters concentrated on migratory ungulates and virtually ignored the resident inselberg ungulates throughout the occupation. Faunas of the last glacial maximum are dominated by an extinct small alcelaphine antelope. Arid-adapted ungulates are present that are regionally absent historically, and Pelorovis is present as well. The small alcelaphine and arid-adapted ungulates are absent in the Holocene deposits. This suggests that there was an expansion of dry savannas during the last glacial maximum. The last glacial maximum aridity, combined with a lack of pastoral-set fires, would have resulted in a vegetative mosaic distinct from the present. Dry woody growth and dry and/or tall grass, all of which are poor forage for ungulates, would have been common where seasonally moist short grasslands are presently extant. These conditions favored the large-bodied, highly hypsodont species in Africa that became extinct with the onset of wet conditions during the early Holocene.
Single-crystal 40Ar/39Ar age estimates of 392,000 ± 4000 to 330,000 ± 6000 yr from Lainyamok, a middle Pleistocene fossil locality in the southern Kenya rift, document the oldest evidence from sub-Saharan Africa of a diverse, large mammal fauna consisting entirely of extant species. The inferred age of this fauna implies an upper limit for extinction of species that characterize well-calibrated, mid-Pleistocene fossil assemblages in East Africa. For its age and species richness, the Lainyamok fauna is surprising for its lack of extinct forms (e.g., the bovine Pelorovis) well documented in later faunal assemblages of East and South Africa. Definitive presence of the South African blesbok (Damaliscus dorcas) is also unexpected, especially as this alcelaphine bovid is the dominant large mammal in the Lainyamok fauna. These age estimates and the faunal composition at Lainyamok indicate that geographic ranges and taxonomic associations of extant largebodied mammals were susceptible to wide fluctuations in sub-Saharan Africa over the past 330,000 yr. This inference is consistent with the hypothesis of nonanalogue, or ephemeral, biotas believed to characterize late Quaternary ecosystems of northern continents.
The archaeological deposits at Mumba rockshelter, northern Tanzania, have been excavated for more than 70 years, starting with Margit and Ludwig Köhl-Larsen in the 1930s. The assemblages of Middle Stone Age (MSA) and Later Stone Age (LSA) artefacts collected from this site constitute the type sequences for these cultural phases in East Africa. Despite its archaeological importance, however, the chronology of the site is poorly constrained, despite the application since the 1980s of several dating methods (radiocarbon, uranium-series and amino acid racemisation) to a variety of materials recovered from the deposits. Here, we review these previous chronologies for Mumba and report new ages obtained from optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) measurements on single grains of quartz and multi-grain aliquots of potassium (K) feldspar from the MSA and LSA deposits. Measurements of single grains of quartz allowed the rejection of unrepresentative grains and the application of appropriate statistical models to obtain the most reliable age estimates, while measurements of K-feldspars allowed the chronology to be extended to older deposits. The seven quartz ages and four K-feldspar ages provide improved temporal constraints on the archaeological sequence at Mumba. The deposits associated with the latest Kisele Industry (Bed VI-A) and the earliest Mumba Industry (Bed V) are dated to 63.4 ± 5.7 and 56.9 ± 4.8 ka (thousands of years ago), respectively, thus constraining the time of transition between these two archaeological phases to ~60 ka. An age of 49.1 ± 4.3 ka has been obtained for the latest deposits associated with the Mumba Industry, which show no evidence for post-depositional mixing and contain ostrich eggshell (OES) beads and abundant microlithics. The Nasera Industry deposits (Bed III) contain large quantities of OES beads and date to 36.8 ± 3.4 ka. We compare the luminescence ages with the previous chronologies for Mumba, and briefly discuss how the revised chronology fits in the context of existing archaeological records and palaeoclimatic reconstructions for East Africa.
The debate of climate versus CO2 in controlling the long-term dynamics of tropical African vegetation has focused on events at the upper tree-line, since the relevant paleodata tend to be from mid-elevation sites (~2000–3000m). Less well known is the relative importance of CO2 in regulating the dynamics of tropical lowland (