Article

New evidence for the lack of C 4 grassland expansions during the early Pliocene at Langebaanweg, South Africa

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Abstract

Major C4 grass expansions during the late Miocene in both the Northern and Southern Hemispheres had a major impact on biological communities. We report that the diverse terrestrial fauna of Langebaanweg, South Africa, existed in a local environment that remained C3-dominated during the late Neogene (∼5 Ma). In contrast, other Southern Hemisphere sites at similar latitudes show a clear shift to C4 grasslands well before 5 Ma. Our results are based on stable isotope analyses of enamel carbonate from four artiodactyl and two perissodactyl families from this locality. We also provide insight into the evolution of the current Mediterranean climate system in this part of South Africa.

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... Sedimentary records indicate a transition from fluvial to spring-fed and eolian deposition in southwestern South Africa (Roberts et al., 2011; Eze and Meadows, 2014 ). Data from pre-Holocene mammalian fossils suggest the presence of significant amounts of surface water and a vegetated landscape composed of a fynbos shrubland and grassland mosaic, interspersed with trees and broad-leafed bush, which contrasts the dry, eolian landscapes that are prevalent in southwestern South Africa today (e.g., Luyt et al., 2000; Franz-Odendaal et al., 2002; Stynder, 2009 Stynder, , 2011 Braun et al., 2013). Here we use the carbon and oxygen isotopic composition of fossil herbivore tooth enamel obtained from paleontological and archeological sites in southwestern South Africa to investigate trends in regional climate and hydrology, vegetation and animal diet between the Pliocene and Pleistocene. ...
... These sites are well known for their contribution to our understanding of faunal change and human evolution in South Africa (e.g., Hendey, 1976; Klein, 1978; Berger and Parkington, 1995; Stynder, 1997; Stynder et al., 2001; Klein et al., 2007; Braun et al., 2013). The flora, fauna and sediment records at these sites provide a record of environmental change in the area from the Pliocene and Pleistocene (Luyt et al., 2000; Franz-Odendaal et al., 2002; Stynder, 2009; Roberts et al., 2011; Stynder, 2011; Braun et al., 2013; Hare and Sealy, 2013; Eze and Meadows, 2014). While these sites have been the focus of a variety of paleoecological studies (Table 1 ), currently there is no detailed, integrated record of the hydrological, ecological and climatic changes in southwestern South Africa over the past 5 myr. ...
... Here we define large mammals as N6 kg because the smallest mammal included in this category is the grysbok, which is ~ 10 kg, whereas we refer to the mammals from Elandsfontein with body weights b 6 kg as small mammals, which includes the rodent genera Bathyergus and Otomys. For fossil sites, in southern Africa, the presence or absence of C 3 and C 4 grasses in mammalian diet has been presumed to reflect the presence or absence of winter and summer rainfall (Luyt et al., 2000; Franz-Odendaal et al., 2002; Hare and Sealy, 2013 ). Within a C 3 -dominated ecosystem, the isotopic composition of tooth enamel from large herbivores can be used to tease apart subtleties in the distribution of vegetation (e.g., Luyt et al., 2000; Franz-Odendaal et al., 2002; Hare and Sealy, 2013). ...
... Much like elsewhere on the African continent, however, the integration of C 4 vegetation into the CFR plant biome would have likely been highly heterogeneous within a C 3 dominated system (Feakins et al., 2013). This scenario is supported by the lack of evidence for C 4 grasses at Langebaanweg approximately 5 Ma (Ma = million years ago; Franz-Odendall et al., 2002;Rossouw et al., 2009), and evidence of their presence at younger sites of Elandsfontein (Luyt et al., 2000) and Hoedjiespunt (Hare and Sealy, 2013) suggest that C 4 plants were represented in the CFR during the Quaternary, we understand little about their overall spatial and temporal distribution. ...
... With in situ associated fossils and artifacts, EFT presents the prospect of illuminating the ecological dynamics within a WRZ paleocommunity during an enigmatic period in the southern African record (Fig. 2). Although there are localities in the region of older (Franz-Odendall et al., 2002) and younger age (Berger and Parkington, 1995;Dietl et al., 2005;Matthews et al., 2005;Klein et al., 2007;Faith and Behrensmeyer, 2013;Hare and Sealy, 2013), EFT represents a rare window into the ecosystem and faunal community of the CFR during a period unrepresented at other sites (Klein et al., 2007). ...
... Although the contemporary CFR lies well within the WRZ and is dominated by C 3 vegetation, we understand little about the evolution of this climatic system throughout the Quaternary (Chase and Meadows, 2007). Previous research suggests that C 4 vegetation was not a major component of CFR ecosystems at 5 Ma (Franz-Odendall et al., 2002;Rossouw et al., 2009;Dupont, 2011;Dupont et al., 2013;Hoetzel et al., 2013Hoetzel et al., , 2015, however analyses of enamel from large mammals (Luyt et al., 2000;Hare and Sealy, 2013;Lehmann et al., 2016) suggest a minor presence of C 4 vegetation in the mid-Pleistocene, potentially related to decreased atmospheric pCO 2 conditions during glacial periods. Our study suggests that a C 4 signal within the CFR during this period may be somewhat masked by the wideranging nature of large mammals. ...
... Restionaceae, Ericaceae and Proteaceae, already contributed to the vegetation in southwestern Africa during the Palaeogene (Scholtz 1985;Linder 2003). Grasslands are thought to have broadened globally during the late Miocene-early Pliocene, accompanying summer-rainfall-dominated savanna biomes, which are now firmly established in southern and East Africa (Cerling et al. 1997;Franz-Odendaal et al. 2002). The same time period saw the major radiation of fynbos elements (Goldblatt & Manning 2000;Cowling & Pressey 2001;Linder 2003). ...
... Biostratigraphic dating has been conducted on the mammalians of LBW, especially of the upper Varswater Formation, because of their large numbers and variety; little focus has been placed on the flora of the underlying Elandsfontyn Formation ( Fig. 1; Coetzee 1978;Tankard & Rogers 1978;Hendey 1974Hendey , 1981Hendey , 1982Hendey , 1983Coetzee & Rogers 1982;Franz-Odendaal et al. 2002;Matthews et al. 2006Matthews et al. , 2007. A biostratigraphic age of middle Miocene has been assigned to the Elandsfontyn Formation, late Miocene (10 Ma) age to the lower Varswater Formation (Konings Vlei Gravel Member) and Mio-Pliocene age to the upper Varswater (Dingle et al. 1979;Hendey 1974Hendey , 1981Hendey , 1982Hendey , 1983Coetzee & Rogers 1982). ...
... The latter age, on the basis of palaeomagnetic data, was honed to 5.1 Ma (Roberts et al. 2011). These ages are reaffirmed by the correspondence of Cenozoic Western Cape sea-level fluc-tuation to global Cenozoic sea-level trends (Tankard 1976;Haq et al. 1987;Shackleton 1995;Franz-Odendaal et al. 2002). Coetzee's (1978) pilot study of the organic-rich unit (uppermost Elandsfontyn Formation), below the main fossil bed at LBW, gave the first clues to the subtropical floral assemblages present. ...
Article
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The largest deposit of excellently preserved Mio-Pliocene vertebrate faunas in SouthAfrica is located at the well known Langebaanweg (LBW) site along South Africa’s west coast in the southwestern Cape. This research deals with a core (BH2) drilled at Langebaanweg ‘E’ Quarry, which captures Miocene fluvial deposits that unconformably underlie the Mio-Pliocene deposits. The aim of the study is to constrain fluctuations in climate and ecosystems in the region during the Miocene, using a combination of sedimentology, palynology, and biogeochemistry. The latter is a novel application and includes bulk C and N isotope measurements as well as branched GDGT (glycerol dialkyl glycerol tetraether) membrane lipid compositions of the organic fraction of the core. The mean annual temperature (MAT) at time of deposition and ambient pH values were calculated using the Methylation index of Branched Tetraethers (MBT) and Cyclization ratio of Branched Tetraethers (CBT) proxies. The core samples analysed spanned a depth interval of 17–33 m and had MATs ranging between 12.4°C and 26.6°C and pH range from 4.4 to 6.4. Furthermore, samples showed a low variance and light d13C distribution (from –25.52‰ to –24.27‰) and overall low C/N ratios. Palynological investigation supplemented earlier similar studies, reaffirming alternating sequences of tropical and subtropical elements including wetland taxa and complementing calculated MAT results. Pollen results from the lowermost subsection indicated a species-rich tropical/subtropical Podocarpus dominated forest with MATs at 16.2°C. The pollen-bearing middle subsection shows initially subhumid conditions, with MATs between 15.4 and 26.6°C, similar to the bottom of the section with high Podocarpaceae percentages, low Restionaceae and aquatics. Above this, local taxa, e.g. Restionaceae and algae increase, and a marine influence is indicated by abundant dinoflagellates. The uppermost subsection from a depth of 7.20–7.60 m shows similar conditions (with little marine influence) to that of the lower part of the middle subsection II. Biochemical and sedimentological data are not available for the uppermost subsection. The results suggest that regional Miocene climate showed high amplitude fluctuations (possibly driven by orbital forcing as seen in marine cores), underscoring the potential of biogeochemistry for unravelling past climates and ecosystems. Keywords: Miocene, palms, Podocarpaceae, glycerol dialkyl glycerol tetraethers (GDGTs), South Africa.
... Our study shows that the carrying capacity of the C 3 -dominated LBW environment was high. Odendaal et al., 2002), probably because then (as today) it received predominantly winter rainfall. It maintained an environment of woodlands, fynbos, and lesser components of C 3 grasses (Stynder, 2011) while the fauna shifted from a woodland-adapted faunal community to a savanna-adapted one (Franz-Odendaal et al., 2002). ...
... Odendaal et al., 2002), probably because then (as today) it received predominantly winter rainfall. It maintained an environment of woodlands, fynbos, and lesser components of C 3 grasses (Stynder, 2011) while the fauna shifted from a woodland-adapted faunal community to a savanna-adapted one (Franz-Odendaal et al., 2002). Because of the unusual environment, previous work has focused on the ecology of LBW herbivores, the sector of the animal community that reveals the most direct information about the site's floral community. ...
... Located on the southwestern coast of South Africa and dated to approximately five million years ago (latest Miocene to Early Pliocene), this site has yielded thousands of fossils representing at least 250 vertebrate and invertebrate species from the terrestrial and marine realms (Hendey, 1982). The sheer number and diversity of extinct animals at Langebaanweg (hereafter referred to as LBW) has inspired various studies of the site, on topics such as community structure and evolution (e.g., Hendey, 1969;Matthews et al., 2007), taxonomy (Sanders, 2007), and palaeoenvironment and ecology (Franz-Odendaal et al., 2002;Stynder, 2011;Ungar et al., 2007). The ecology of LBW is of particular interest because the site lies outside the widespread C 4 grassland expansion of the Late Miocene (Franz-Three coeval proboscidean taxa (Loxodonta cookei, Mammuthus subplanifrons, and ...
Article
The co-existence of megaherbivores in present-day ecosystems is uncommon. During the Early Pliocene, three large proboscidean taxa (Anancus capensis, Mammuthus subplanifrons and Loxodonta cookei) co-existed in the strongly C3-dominated Langebaanweg (LBW) environment, on the southwestern coast of South Africa. It is expected that this would have required at least some resource partitioning. To investigate whether/how dietary resources were partitioned, we have measured δ13C and δ18O in tooth enamel from the molars of A. capensis (n = 13), M. subplanifrons (n = 3) and L. cookei (n = 20). δ13C values for A. capensis are more tightly clustered and the mean more negative than for L. cookei and M. subplanifrons. Anancus capensis probably favoured shady, wooded parts of the LBW environment, where it mainly browsed. Loxodonta cookei and M. subplanifrons spent more time in open habitats and were dietarily flexible. The preference for browse of A. capensis may have contributed to its extinction, whereas the dietary flexibility of the genus Loxodonta meant it was able to survive to the present. We did not find significant differences in δ18O values between the three taxa, which suggests that they drank from the same water sources as expected if they were all resident in the LBW palaeoenvironment. Our study shows that the carrying capacity of the C3- dominated LBW environment was high.
... However, evidence from further back in the Quaternary is currently sparse. The earliest evidence for the presence of winter rainfall on the west coast comes from the late Miocene/early Pliocene (~5 Ma) site of Langebaanweg (Franz-Odendaal et al., 2002). δ 13 C values of faunal enamel from this site showed that the west coast probably remained C 3 -dominated throughout the period/s of C 4 grass expansions which occurred globally during the late Miocene and early Pliocene (Cerling et al., , 1998Ségalen et al., 2007). ...
... In paleoenvironmental studies of the west coast (Luyt et al., 2000;Franz-Odendaal et al., 2002), dominance of C 3 grasses has been regarded as a useful proxy for the presence and intensity of the WRZ, since a cool growing season is a prerequisite for C 3 grass growth. Global patterns in the relative abundance of C 3 and C 4 grass species are well explained by differences in quantum yielda measure of CO 2 gained for each photon absorbed (Ehleringer, 1978). ...
... However, it is not immediately clear why the HDP1 reedbuck should reflect a greater C 3 component than the HDP1 browsers. The clear distinction between δ 13 C values of grazing taxa from HDP1 and those of EFTM and EFTBC is evident in Fig. 3. δ 13 C data from the site of Langebaanweg on the west coast (in this instance omitted because there are no measurements for species represented at HDP1) also shows values for grazers in the range of C 3 grasses (Franz-Odendaal et al., 2002). ...
... Some authors 29,30 have suggested that tectonic uplift in southwestern Africa would have led to a cooling in the BUS at 12 mya, and after 5 mya, but the timing and cause of such tectonic events, and even their occurrence, is controversial 6,31 . The initiation of the BUS has frequently been linked in the literature to summer aridity and the entrenchment of the current winter rainfall pattern on the west coast 6,24,32,33 , and this in turn has been taken to have influenced other processes, such as the diversification of plants (see Altwegg et al. 33 -although a recent analysis 1 failed to find proof that seasonal aridity at ~8 mya triggered floristic radiation and diversification in the Cape Floral Region). ...
... The presence of cool-growing C 3 grasses at LBW during the deposition of MPPM sediments was taken to indicate that the present-day climatic regime of winter wet/summer dry was established early in the Pliocene epoch. 32 Using the vegetation to establish the rainfall regime is, however, questionable, given that fynbos and C 3 grasses both have a C 3 signature, and the contribution of C 3 grasses versus that of C 3 fynbos at LBW is undetermined. In addition, there are indications that the contribution from C 3 grasses to the general C 3 signature at LBW was small, as Stynder 10 suggests that fossil bovid species indicate that grass was scarce, and the environment may have been heavily wooded. ...
... As mentioned previously, such studies have typically used the formation of the BUS as a proxy for the inception of the winter rainfall regime along the West Coast and the beginning of aridification. 6,24,32,33 Certain fynbos taxa such as Restionaceae, Ericaceae and Proteaceae formed part of the vegetation in southwestern Africa during the Palaeogene 53 and fossil pollen research indicates that fynbos taxa have formed part of west coast ecosystems since well before the inception of BUS and a winter rainfall regime 14,15,23,51,52,54 . Hoffman et al.'s 1 habitat reconstruction for the dated phylogenies of 12 plant clades from the Cape Floral Region in southern Africa indicated that they evolved in aseasonal rainfall environments. ...
Article
Full-text available
No direct palaeoclimatic proxies have been available to indicate the seasonality or amount of rainfall on the west coast of southern Africa during the Early Pliocene. The Benguela Upwelling System (BUS) is today one of the factors responsible for the present-day aridity on the west coast of southern Africa. The initiation of the BUS is frequently linked to the entrenchment of aridity and the establishment of the current winter rainfall pattern on the west coast; however, marine proxies are inconclusive regarding the effects of past fluctuations in the BUS and sea surface temperatures on the rainfall regime. Neither the fossil evidence nor the fact that plants using the C3 photosynthetic pathway predominate at this time, provide direct evidence of winter rainfall at Langebaanweg. We challenge certain assumptions which are commonly made in the literature regarding the timing of inception of a winter rainfall regime on the west coast and the onset of aridity in the Langebaan region, and provide new evidence as to seasonality of rainfall at Langebaanweg in the Early Pliocene. Herein, the identification of frog species from the genus Ptychadena from Langebaanweg provides new and compelling evidence for a summer rainfall regime, or of at least significant summer rainfall, at 5.1 mya in the southwestern Cape of South Africa.
... Stable isotope analyses of a variety of ungulate specimens from 'E' Quarry (32°58'S, 18°7'E), a well-known Late Miocene to Early Pliocene fossil locality near the town of Langebaanweg (Fig. 1), indicate that the local environment remained dominated by C 3 taxa. 15 While this might indicate a closed environment dominated by trees, shrubs and forbs, the occurrence of several species of high-crowned (hypsodont) ungulates in the 'E' Quarry faunal assemblage, hint at the presence of a substantial grass component. Despite this evidence, very little is known about the evolution, nature and importance of grass in the Langebaanweg 'E' Quarry biome. ...
... [38][39][40] The presence of hypsodont ungulates with C 3 stable carbon isotope values suggests that C 3 grasses were the prevalent grass type and also implies that the modern wet winter/dry summer climate regime was established by Late Miocene to Early Pliocene times. 15 Whereas fynbos vegetation today is characterised by an insignificant C 3 grass component, 41 the 'E' Quarry Late Miocene/Early Pliocene habitat may have included a substantial C 3 grass component along with riverine forests and fynbos shrublands. 42 ...
Article
Full-text available
At the end of the Miocene epoch, C4 grasslands began to expand at the expense of tree-, shrub- and forb-dominated C3 ecosystems. While C4 grasses were spreading throughout most regions of the world, C3 grasses may have been spreading along South Africa's southwest coast. Stable isotope analyses of hypsodont fossil ungulates from 'E' Quarry, a well-known Late MioceneJEarly Pliocene fossil locality near the town of Langebaanweg, suggest that the local environment might have included a substantial C, grass component. Besides this indirect evidence, little Is known about the evolution, nature and Importance of grass in the 'E' Quarry biome. As a preliminary step towards addressing these questions, we initiated a trial investigation to assess whether sediments at the site are conducive to the preservation of phytoliths, an important tool in the reconstruction of palaeohabitats. Results indicate that fossil phytoliths are sufficiently well preserved to allow a comprehensive analysis of the 'E' Quarry phytolith assemblage.
... Studies of ratite eggshell showed that this occurred in Namibia only in the last 3.5 million years (Segalen et al., 2002;Ségalen et al., 2007;Ségalen and Lee-Thorp, 2009). However, C 4 grasses did not expand significantly into more temperate southern African environments such as high-altitude grasslands and the WRZ (Franz-Odendaal et al., 2002;Mucina and Rutherford, 2006;Vogel et al., 1978). Today these regions are dominated by C 3 vegetation, although up to 5% of grass species in fynbos vegetation may be C 4 , and up to 25% in renosterveld . ...
... δ 13 C of faunal tooth enamel and pedogenic carbonates from archaeological and fossil sites in the WRZ indicate that the winter rainfall regime has been in effect for at least 5 Myr. At the site of Langebaanweg (Fig. 1), ca. 5 Myr old tooth enamel from grazing species reflect the consumption of C 3 grasses (Franz-Odendaal et al., 2002;Lehmann et al., 2016) . ...
Article
The relationship between ungulate stable carbon isotope values and environmental variables (temperature, relative humidity, precipitation) remains poorly understood. In this paper, we evaluate this relationship for, predominantly, C3 ecosystems in the winter rainfall areas of southern Africa. In our dataset (290 individuals representing 23 species), δ¹³C values of ungulate enamel are significantly correlated with mean annual precipitation (MAP), moisture index (MI) and summer aridity index (SAI), variables that also influence the distribution of C3/C4 grasses. Our study confirms previous findings that faunal δ¹³C values in C3 ecosystems are most strongly correlated with variables related to precipitation. δ¹³Cenamel values for ungulate browsers are more strongly correlated with a larger number of environmental variables than values for grazers and mixed feeders and vary according to vegetation type. We apply regressions derived from the modern dataset to estimate palaeoclimatic shifts based on δ¹³Cenamel values of browsing fauna at the Pleistocene sites of Hoedjiespunt and Elandsfontein in South Africa.
... Studies of ratite eggshell showed that this occurred in Namibia only in the last 3.5 million years (Segalen et al., 2002;Ségalen et al., 2007;Ségalen and Lee-Thorp, 2009). However, C 4 grasses did not expand significantly into more temperate southern African environments such as high-altitude grasslands and the WRZ (Franz-Odendaal et al., 2002;Mucina and Rutherford, 2006;Vogel et al., 1978). Today these regions are dominated by C 3 vegetation, although up to 5% of grass species in fynbos vegetation may be C 4 , and up to 25% in renosterveld . ...
... δ 13 C of faunal tooth enamel and pedogenic carbonates from archaeological and fossil sites in the WRZ indicate that the winter rainfall regime has been in effect for at least 5 Myr. At the site of Langebaanweg (Fig. 1), ca. 5 Myr old tooth enamel from grazing species reflect the consumption of C 3 grasses (Franz-Odendaal et al., 2002;Lehmann et al., 2016) . ...
... Hippopotamus amphibius is commonly assumed to be a pure browser, but recent stable isotope data show that Hippopotamus amphibius has no distinct dietary preference and hippos in Africa can have diets ranging from a pure C 4 to pure C 3 diet (Zazzo et al., 2000;Franz-Odendaal et al., 2002;Boisserie et al., 2005;Cerling et al., 2008;Harris et al., 2008;Brachert et al., 2010). Therefore, these territorial, water-dependent mammals are particularly useful for paleoenvironmental studies. ...
... Equidae in Eastern Africa adapted their diet from C 3 -dominant to C 4dominant as a response to the global expansion of C 4 biomass during the late Miocene (Cerling et al., 1997). Except at Langebaanweg (South Africa), where C 4 grasses were not established by 5 Ma (Franz-Odendaal et al., 2002), equid enamel younger than ca. 7 Ma in tropical and sub-tropical Africa yields δ 13 C values in the range of − 4‰ to +3‰, indicating C 4 dominated to exclusive C 4 grass diets (Morgan et al., 1994;Bocherens et al., 1996;Cerling et al., 1997;Kingston, 1999;Zazzo et al., 2000;Cerling et al., 2003b;Kingston, 2011). ...
... As a consequence, C 4 plants have an average ␦ 13 C value of Ϫ12 Ϯ 1‰, with a more restricted isotopic range from Ϫ15‰ to Ϫ7‰. CAM plants are capable of fixing carbon with either photosynthetic pathway and therefore display ␦ 13 C plant values covering the range for C 3 and C 4 plants (see reviews and references in Smith and Epstein 1971;Bocherens et al. 1996;Grö cke 1997a,b;Ehleringer et al. 1997;Collatz et al. 1998;Zazzo et al. 2000;Freeman and Colarusso 2001;and Franz-Odendaal et al. 2002). ...
... M. Nieto personal communication 2002). Sim-ilar results were reported by Bocherens et al. (1996) and Franz-Odendaal et al. (2002) in the isotopic analyses of terrestrial mammals from the early-middle Pleistocene site at Tighenif, Algeria, and from the early Pliocene site at Langebaanweg, South Africa, respectively. In both localities all ungulate species showed ␦ 13 C enamel values exclusive of a diet of C 3 plants. ...
Article
Ecomorphological and biogeochemical (trace element, and carbon, nitrogen, and oxygen isotope ratios) analyses have been used for determining the dietary niches and habitat preferences of large mammals from lower Pleistocene deposits at Venta Micena (Guadix-Baza Basin, Spain). The combination of these two approaches takes advantage of the strengths and overcome the weakness of both approaches. The range of δ 13 C collagen values for ungulate species indicates that C 3 plants were dominant in the diet of these mammals. δ 13 C collagen values vary among ungulates: perissodactyls have the lowest values and bovids the highest ones, with cervids showing intermediate values. The hypsodonty index measured in lower molar teeth and the relative length of the lower premolar tooth row indicate that the horse, Equus altidens , was a grazing species, whereas the rhino, Stephanorhinus etruscus , was a mixed feeder in open habitats. The similar δ 13 C collagen values shown in both perissodactyls does not reflect differences in feeding behavior with other ungulates, but rather a lower isotope enrichment factor in these monogastric herbivores than in ruminants, owing to their lower metabolic efficiency. The cervids Eucladoceros giulii and Dama sp. show low hypsodonty values, indicating that they were mixed feeders or browsers from forested habitats, an ecomorphologically based conclusion corroborated in the former by its low δ 15 N collagen content (canopy effect). Bovid species (Bovini aff. Leptobos, Soergelia minor , and Hemitragus albus ) presumably inhabited open environments, according to their comparatively high hypsodonty and δ 15 N collagen values. Carnivore species ( Homotherium latidens, Megantereon whitei, Pachycrocuta brevirostris, Canis falconeri , and Canis etruscus ) exhibit higher δ 15 N collagen values than ungulates. These results record the isotopic enrichment expected with an increase in trophic level and are also supported by low bone Sr.Zn ratios. The elevated δ 15 N collagen value for a sample of Mammuthus meridionalis , which came from an individual with unfused epiphyses, confirms that it was a suckling animal. The δ 15 N collagen value of the scimitar-cat H. latidens is well above that obtained for the young individual of Mammuthus , which indicates that juvenile elephants were an important part of its diet. The hippo, Hippopotamus antiquus , yielded unexpectedly high δ 15 N collagen values, which suggest feeding on aquatic, non-N 2 -fixing plants. The high δ 18 O hydroxyl values of bovids Hemitragus and Soergelia and of cervid Dama indicate that these ungulates obtained most of their water requirements from the vegetation. The megaherbivores and Eucladoceros exhibit the lowest δ 18 O hydroxyl values, which suggest increased water dependence for them. Paleosynecological analysis was based on the relative abundance of species of large mammals from different ecological categories, determined by feeding behavior and locomotion types. The comparison of the frequencies of such categories in Venta Micena with those found in modern African communities indicates that the composition of the paleocommunity closely resembles those of savannas with tall grass and shrubs. The net above-ground primary productivity estimated for the on-crop biomass of the mammalian species preserved in the fossil assemblage also yields a figure congruent with that expected for an open environment.
... Stable isotope analyses of a variety of ungulate specimens from 'E' Quarry (32°58'S, 18°7'E), a well-known Late Miocene to Early Pliocene fossil locality near the town of Langebaanweg (Fig. 1), indicate that the local environment remained dominated by C 3 taxa. 15 While this might indicate a closed environment dominated by trees, shrubs and forbs, the occurrence of several species of high-crowned (hypsodont) ungulates in the 'E' Quarry faunal assemblage, hint at the presence of a substantial grass component. Despite this evidence, very little is known about the evolution, nature and importance of grass in the Langebaanweg 'E' Quarry biome. ...
... [38][39][40] The presence of hypsodont ungulates with C 3 stable carbon isotope values suggests that C 3 grasses were the prevalent grass type and also implies that the modern wet winter/dry summer climate regime was established by Late Miocene to Early Pliocene times. 15 Whereas fynbos vegetation today is characterised by an insignificant C 3 grass component, 41 the 'E' Quarry Late Miocene/Early Pliocene habitat may have included a substantial C 3 grass component along with riverine forests and fynbos shrublands. 42 ...
Article
Full-text available
At the end of the Miocene epoch, C4 grasslands began to expand at the expense of tree-, shrub- and forb-dominated C3 ecosystems. While C4 grasses were spreading throughout most regions of the world, C3 grasses may have been spreading along South Africa’s southwest coast. Stable isotope analyses of hypsodont fossil ungulates from ‘E’ Quarry, a well-known Late Miocene/Early Pliocene fossil locality near the town of Langebaanweg, suggest that the local environment might have included a substantial C3 grass component. Besides this indirect evidence, little is known about the evolution, nature and importance of grass in the ‘E’ Quarry biome. As a preliminary step towards addressing these questions, we initiated a trial investigation to assess whether sediments at the site are conducive to the preservation of phytoliths, an important tool in the reconstruction of palaeohabitats. Results indicate that fossil phytoliths are sufficiently well preserved to allow a comprehensive analysis of the ‘E’ Quarry phytolith assemblage.
... Elandsfontein is located in a region that has been dominated by C 3 vegetation since at least the Early Pliocene (Franz-Odendaal et al., 2002;Rossouw et al., 2009;Stynder, 2011). While sclerophyllous shrubland (fynbos) predominate in the contemporary environment, this may not have been the case during the Middle Pleistocene. ...
... Differences in the biogeographic distribution of Elephas and Loxodonta in the Pleistocene fossil record of Africa could be associated with the habitat preference of each genus. Elandsfontein was dominated by C 3 graze and browse in the Middle Pleistocene (e.g., Franz-Odendaal et al., 2002;Stynder, 2009), and L. atlantica was the only proboscidean present there. Likewise, the Middle Pleistocene Ternifine Quarry in northern Africa shows evidence for C 3 grasslands (Bocherens et al., 1996), and Loxodonta (africana and atlantica) dominated the region. ...
Article
Elandsfontein (EFT) is a Middle Pleistocene archaeological/paleontological site located in the Western Cape Province of South Africa. The largest herbivore in the assemblage is Loxodonta atlantica zulu, an extinct member of the genus that includes modern African elephants. No Elephas recki specimens were recovered at EFT, despite their common occurrence in other regions of Africa at the same time. Because E. recki and L. atlantica molars are similar in appearance, but the two species are traditionally viewed as dominating different regions of Africa during the Pleistocene, isolated molars may on occasions have been assessed to species level on the basis of geography rather than morphology. The last morphologic evaluation of EFT elephants was conducted in the 1970s, and revisiting this issue with new specimens provides added insight into the evolution of elephants in Africa. Reevaluating morphological characteristics of EFT elephant molars, through qualitative and quantitative description and comparison with Middle Pleistocene E. recki recki, L. atlantica atlantica, and L. atlantica zulu molar morphology, corroborates assessment of EFT elephants as L. a. zulu. Two recently discovered, previously undescribed molars from EFT show that molars of L. a. zulu exhibit greater variation in enamel thickness, lamellar frequency, and occlusal surface morphology than previously reported. An update of the Pleistocene biogeography of Loxodonta and Elephas indicates that fossil remains of both are often found at the same localities in eastern Africa. Their rare co-occurrences in the north and south, however, suggest geographic separation of the two genera in at least some regions of Africa, which may have been based on habitat preference.
... Recent research on the bird and large mammal faunas from LBW has not resulted in a clear indication as to the nature of the vegetation which existed at 5.1 Ma. No modern analogy appears to exist, although research has clearly indicated that LBW was dominated by C 3 vegetation and that the global spread of C 4 grasses around eight to six million years ago did not occur (Franz-Odendaal et al. 2002;Rossouw et al., 2009). A dental mesowear study and microwear texture analysis of LBW bovid species suggests a heavily wooded environment with little grass. ...
... The diverse and rich (∼19 species) frog community at LBW serves as a proxy for rainfall on the west coast at 5.1 Ma and indicates that rainfall on the west coast was considerably higher in the early Pliocene, and aridificiation of the west coast as seen today had not yet begun. Rainfall at this time is likely to have fallen mainly in winter, as suggested by stable isotope analysis of enamel carbonate of large mammals at the site (Franz-Odendaal et al. 2002). ...
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Abstract.—The 5.1 million year old fossil site of Langebaanweg (LBW) has provided a wealth of information on the evolution of west coast ecosystems along the southern west coast of South Africa and numerous taxa, including small and large mammals, and birds, make a first appearance in the fossil record at the site. Langebaanweg also contains a rich and diverse anuran fauna which derives from the two main fossil-bearing members at the site. This study identified six families, including Hyperoliidae, Brevicipitidae, Pxyicephalidae, Pipidae, Heleophrynidae and Bufonidae, and some 19 taxa have been differentiated. The majority of frog families identified from the LBW fossil material currently contain a high number of species endemic to the southwestern Cape or South Africa. LBW provides an insight into how current patterns of endemism and distribution may have evolved, and illustrates that the frog community in a region may change substantially over time. The progressive aridification of the west coast subsequent to 5.1 Ma has left very little trace of the rich and diverse frog community which existed during the early Pliocene, and diversity and endemnicity are low today. This challenges the generally held assumption that centres of origin may have a bearing on current-day frog distributions.
... PP30 fossil assemblage are more enriched in 13 C than other herbivorous taxa from C 3 vegetation communities in South Africa (Lee- Thorp et al., 1989;Thorp and Van Der Merwe, 1987) and in East Africa (Cerling and Harris, 1999). The lowest values from PP30 large faunal specimens barely overlap with d 13 C enamel values (À14.9‰ to À9.3‰) reported from the clearly C 3 early Pliocene assemblage of Langebaanweg on the Western Cape, South Africa (Franz-Odendaal et al., 2002). A similar phenomenon has been noted for glacial period faunas in the Southwestern Cape and elsewhere (Hare and Sealy, 2013). ...
... Given the catholic dietary preferences of many small mammals(Leichliter et al., 2016) the wide range of intraspecific d 13 C variation within the fossil Otomyines is suggestive of a local environment that, given the comparably depleted stable carbon isotope values of these taxa, is dominated by C 3 vegetation cover but with some component of C 4 grass in the nearby environment. The range of O. karoensis and O. irroratus d 13 C enamel values (À17.5‰ to À9.6‰, and À16.10‰to À10.7‰) overlap with the large fauna stable carbon isotope data reported for the C 3 Pliocene Langebaanweg fossil assemblage (À14.9‰ to À9.3‰,Franz-Odendaal et al., 2002) and for modern/ historical large C 3 consumers in the Cape (approximately À16‰ to À13‰, Lee-Thorp et al., 1989). The results are thus strongly suggestive of C 3 dominated vegetation in the immediate vicinity of PP30 at~151yr.Although the most depleted of mole rat d 13 C enamel values overlap with the most enriched specimen of the Otomyinae, the distribution of carbon isotope ratios in the mole rats sampled are statistically distinct from those of the other small mammals. ...
Article
Proxy records dating to marine isotope stage 6 on the south coast of South Africa are rare. This study presents integrated micromammal and macromammal stable isotope palaeoenvironmental proxy data from one of the few MIS 6 fossil occurrences in the region, a fossil brown hyena (Parahyena brunnea) den, Pinnacle Point 30 (PP30). Two predators with significantly different foraging ranges aggregated the large and small mammal components of the PP30 fossil assemblage. The large mammal specimens were brought to PP30 by Parahyena brunnea with an expansive daily foraging radius that focused on the Palaeo-Agulhas Plain. The micromammal taxa were deposited at the site primarily by the spotted eagle owl, Bubo africanus, with a foraging radius of ∼3 km, and would have sampled the ecotone between the Palaeo-Agulhas Plain and the Cape coastal lowlands. The large and small mammal components of the PP30 assemblage thus sample palaeovegetation at different geographic scales; micromammal stable isotope data act as a proxy for local conditions, while macromammal data integrate information at a broader scale. Comparison of the stable carbon isotope data obtained from the micromammal and macromammal fossil specimens suggests that these two assemblage components intersected vegetation with differing proportions of C4 grasses. Micromammal δ¹³C proxy data indicates that, immediately local to the site, a C3 dominated vegetation was present, while the large mammal δ¹³C proxy data shows evidence of a vegetation community with a greater C4 grass component that likely occurred somewhat more distant from the site itself on the Palaeo-Agulhas Plain.
... This quarry lies within the Bredasdorp Formation (Hendey, 1982), although its earliest part is likely to represent fluviatile facies of the earlier Varswater Formation (Hendey, 1974). Palaeonvironmental studies focusing on the LBW area suggest that the current mediterranean climate of wet, cold, winters and dry, warm, summers was established in the late Miocene/early Pliocene (Franz-Odendaal et al., 2002). By that time, LBW was the delta/estuary (Hendey, 1982) of the palaeo-Berg river (Roberts et al., 2011), which constituted the main freshwater source for the animals inhabiting the area (Lehmann et al., 2016). ...
... By that time, LBW was the delta/estuary (Hendey, 1982) of the palaeo-Berg river (Roberts et al., 2011), which constituted the main freshwater source for the animals inhabiting the area (Lehmann et al., 2016). The swampy basin was surrounded by woodland, fynbos shrubland (Hendey, 1981;Scott, 1995;Ungar et al., 2007) and, to a lesser extent (Stynder, 2011), by C 3 grasslands (Franz-Odendaal et al., 2002;Lehmann et al., 2016). ...
Article
We studied the bone and dental histology of the tri-dactyl equid Eurygnathohippus hooijeri, one of the most iconic mammals found at the world-renowned Pliocene site of Langebaanweg, South Africa, to reconstruct important features of its life history. Our results show that key life-history events, such as weaning, skeletal maturity and reproductive maturity, occurred later in this African hipparionine compared with European three-toed equids and several extant Equus. Its late life-history schedule agrees with an ecological context of low adult extrinsic mortality and low juvenile survival rates. We also observed high rates of bone growth in Eu. hooijeri that were probably achieved through a high-quality diet and plentiful available water. Our research highlights the significance of combining bone and dental histology in the same taxon to obtain refined palaeobiological information about extinct vertebrates.
... Many paleontological research projects in Africa now incorporate isotopic aspects to the work, and some isotope results are available from many study sites including Allia Bay (Schoeninger et al., 2003b), the Baringo Basin , Chorora (Bernor et al., 2004), Gona , Fort Ternan , Laetoli (Kingston and Harrison, 2007), Kanapoi , Langebaanweg (Franz-Odendaal et al., 2002), Lothagam (Leakey et al., 1996;Cerling et al., 2003a), Makapansgat Isotope fractionation describes the phenomenon that different isotope ratios are found in isotopic equilibrium with each other in different phases. For example, the heavy isotope 18 O is enriched in liquid water relative to water vapor; this enrichment is known as fractionation and is defi ned as ␣AB ϭ RA/RB ϭ (1,000 ϩ ␦A)/(1,000 ϩ ␦B), ...
Chapter
Stable isotopes have become an important tool to study diets and behavior of fossil mammals, but the path to acceptance has been long and arduous. Phosphate studies apply only to oxygen isotopes and dietary information is lacking; likewise, collagen is rarely preserved in fossils older than some thousands of years. This chapter discusses isotope ratios that are preserved in the carbonate component of tooth enamel. It first reviews isotopic analysis of the diets of extant mammals from Africa and looks at the dietary history of different mammalian lineages. It then examines the correspondence between the isotopic evidence for the transition from a C3 to a C4 world and the paleontological evidence for faunal change at the end of the Miocene and beginning of the Pliocene as shown by the faunal assemblages from Lothagam, northern Kenya. This faunal turnover is one of the most marked in the Cenozoic. Lastly, the chapter discusses future directions of stable isotope paleoecology.
... The data have not been critically examined for evidence of repeated fires (a fire regime) versus rare catastrophic fires. The vegetation at Langebaanweg was a mosaic of woodland, C3 grassland and some fynbos elements and supported a rich megafauna including giraffids, equids, suids (pigs), bovids, rhinocerotids, hippopotamids, and elephantids (Franz-Odendaal et al., 2002). This Pliocene ecosystem contrasts strikingly with the present-day low pyrophytic fynbos shrublands supporting a sparse modern fauna of small-bodied antelope (Klein et al., 2007). ...
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Modern flammable ecosystems include tropical and subtropical savannas, steppe grasslands , boreal forests, and temperate sclerophyll shrublands. Despite the apparent fiery nature of much contemporary vegetation, terrestrial fossil evidence would suggest we live in a time of low fire activity relative to the deep past. The inertinite content of coal, fossil charcoal, is strikingly low from the Eocene to the Pleistocene and no charcoalified mesofossils have been reported for the Cenozoic. Marine cores have been analyzed for charcoal in the North Pacific, the north and south Atlantic off Africa, and the south China sea. These tell a different story with the oldest records indicating low levels of fire activity from the Eocene but a surge of fire from the late Miocene (∼7 Ma). Phylogenetic studies of woody plants adapted to frequent savanna fires show them beginning to appear from the Late Miocene with peak origins in the late Pliocene in both South American and African lineages. Phylogenetic studies indicate ancient origins (60 Ma+) for clades characteristic of flammable sclerophyll vegetation from Australia and the Cape region of South Africa. However, as for savannas, there was a surge of speciation from the Late Miocene associated with the retreat of closed fire-intolerant forests. The wide geographic spread of increased fire activity in the last few million years suggests a global cause. However, none of the potential global factors (oxygen, rainfall seasonality, CO 2, novel flammable growth forms) provides an adequate explanation as yet. The global patterns and processes of fire and flammable vegetation in the Cenozoic, especially since the Late Miocene, deserve much more attention to better understand fire in the earth system.
... The range of ␦ 13 C values measured in the VM herbivores (Ϫ27‰ to Ϫ20‰; see Fig. 2) indicates that they fed exclusively on C 3 vegetation, which confirms that C 4 grasses were absent from southeast Spain during early Pleistocene times (Palmqvist et al., 2003). Similar results have been reported in other early-middle Pleistocene sites of North and South Africa, in which grazing ungulates show ␦ 13 C values indicative of a diet of C 3 grasses (Bocherens et al., 1996b;Franz-Odendaal et al., 2002). ...
Article
Biogeochemical (δ13C, δ15N, and δ18O values) and ecomorphological analyses of the early Pleistocene fauna of Venta Mena (Orce, Guadix-Baza basin, SE Spain) provide interesting clues on the physiology, dietary regimes, habitat preferences, and ecological interactions of large mammals. Such inferences are useful in deciphering aspects of paleocommunity structure and predator-prey relationships. Specifically, the hypsodonty index combined with δ13C values allows classifying the ungulates among grazers from open habitat (Equus altidens, Bison sp., Praeovibos sp., Hemitragus albus, Hippopotamus antiquus, and Mammuthus meridionalis), mixed feeders (Soergelia minor and Pseudodama sp.), and browsers from canopy areas (Stephanorhinus sp. and Praemegaceros cf. verticornis). Given that δ13C values indicate that all these herbivores fed exclusively on C3, plants, significant differences in isotopic values between perissodactyls (monogastric, hindgut fermenters) and ruminants (foregut fermenters) reflect differences in digestive efficiency. Values of δ18O indicate the dietary water source of ungulates, revealing that Pseudodama sp., Hemitragus albus, and Soergelia minor obtained a significant fraction of their metabolic water from vegetation. Carnivores show higher δ15N values than herbivores, which records the isotopic enrichment expected with an increase in trophic level. Hippopotamus antiquus and Praeovibos sp. have unexpectedly high δ15N values, suggesting that they predominantly consumed aquatic plants and lichens, respectively. Inferences on predator-prey relationships, derived from the use of linear mixing models, indicate resource partitioning among sympatric predators; saber-tooth Megantereon whitei and jaguar Panthera cf. gombaszoegensis were ambushers in dosed habitat while saber-tooth Homotherium latidens and wild dog Lycaon lycaonoides were coursing predators in open plains. The giant hyena Pachycrocuta brevirostris scavenged the prey of these hypercarnivores.
... The data have not been critically examined for evidence of repeated fires (a fire regime) versus rare catastrophic fires. The vegetation at Langebaanweg was a mosaic of woodland, C3 grassland and some fynbos elements and supported a rich megafauna including giraffids, equids, suids (pigs), bovids, rhinocerotids, hippopotamids, and elephantids (Franz-Odendaal et al., 2002). This Pliocene ecosystem contrasts strikingly with the present-day low pyrophytic fynbos shrublands supporting a sparse modern fauna of small-bodied antelope (Klein et al., 2007). ...
Article
Full-text available
Modern flammable ecosystems include tropical and subtropical savannas, steppe grasslands, boreal forests, and temperate sclerophyll shrublands. Despite the apparent fiery nature of much contemporary vegetation, terrestrial fossil evidence would suggest we live in a time of low fire activity relative to the deep past. The inertinite content of coal, fossil charcoal, is strikingly low from the Eocene to the Pleistocene and no charcoalified mesofossils have been reported for the Cenozoic. Marine cores have been analyzed for charcoal in the North Pacific, the north and south Atlantic off Africa, and the south China sea. These tell a different story with the oldest records indicating low levels of fire activity from the Eocene but a surge of fire from the late Miocene (~7 Ma). Phylogenetic studies of woody plants adapted to frequent savanna fires show them beginning to appear from the Late Miocene with peak origins in the late Pliocene in both South American and African lineages. Phylogenetic studies indicate ancient origins (60 Ma+) for clades characteristic of flammable sclerophyll vegetation from Australia and the Cape region of South Africa. However, as for savannas, there was a surge of speciation from the Late Miocene associated with the retreat of closed fire-intolerant forests. The wide geographic spread of increased fire activity in the last few million years suggests a global cause. However, none of the potential global factors (oxygen, rainfall seasonality, CO2, novel flammable growth forms) provides an adequate explanation as yet. The global patterns and processes of fire and flammable vegetation in the Cenozoic, especially since the Late Miocene, deserve much more attention to better understand fire in the earth system.
... Since the household is the basic management unit of the grasslands in Inner Mongolia (Hou et al. 2012), the objective of the present work was to understand the relative importance of grazing and temperature in determining the relative abundance of C 4 plants in these grasslands at this scale. Bearing in mind that temperature may affect the relative abundance of C 4 plants at a large temporal-spatial scale, grazing may play a more important role at a smaller temporal-spatial scale (Franz-Odendaal et al. 2002;Reeder et al. 2004;Bell et al. 2012). ...
Article
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Increases in temperature and grazing intensity are believed to promote the relative abundance of C4 plants in grasslandcommunitiesinInnerMongolia.However,thereisalackofunderstandingastowhichfactoristheprimarydriver at the household scale. The relative abundance of C4 plants in grassland communities within 32 households was monitored over a 5-year period (2008-12) in the typical steppe region of Inner Mongolia. The relationships between the mean annual temperature, grazing intensity and their combinations on the patterns of the relative abundance of C4 plants across the land managed by these households were analysed. The results showed that (1) the herbage mass of the typical steppe grassland was mainly composed of C3 plants (87%); (2) the C4 plants were more sensitive to, and can be used as indicators of, environmentalchanges.TheseC4speciesincludedCleistogenessquarrosa(Trin.)Keng,ChenopodiumglaucumLinn.and Salsola collina Pall.; (3) both increasing temperature and grazing intensity promoted the relative abundance of C4 plants. Grazing intensity was the primary driver of the change in relative abundance of C4 plants in this region. Not only did grazing change the micro-environment of the grasslands, but also the C3 species were preferentially grazed by the livestock. Comparison of the results with previous studies on the temporal variation in the abundance of C4 plants suggests that the relative importance of grazing and climatic factors depends on the spatial scales of the studies, with climate being of greater importance at the regional rather than the household scale.
... The east-west dichotomy between summer and winter rains is likely to have characterized the prehistoric landscapes inhabited by blue antelope. Isotopic analysis of presumed grazers from Langebaanweg (20 km north-west of Elandsfontein, Fig. 1) indicate diets of C 3 grasses, suggesting that the dominance of winter rainfall on the west coast dates to at least the early Pliocene (Franz-Odendaal et al., 2002). Parallel evidence has been obtained from mid-Pleistocene grazers at nearby Elandsfontein (Luyt et al., 2000) and Hoedjiespunt (Hare & Sealy, 2013). ...
Article
AimPalaeoecological data are crucial to understanding the historical extinction of the blue antelope (Hippotragus leucophaeus). This study examined late Quaternary fossil evidence bearing on the blue antelope's calving and migratory habits. LocationCape Floristic Region (CFR), South Africa. Methods Blue antelope mortality patterns were reconstructed from dental remains from fossil assemblages spanning the last c. 200,000 years and located in the CFR's winter and year‐round rainfall zones. Two demographic measures were examined: (1) the frequencies of juveniles relative to adults; and (2) the frequencies of neonates relative to older juveniles. Geographical trends were examined across a longitudinal gradient of decreasing winter rainfall and increasing summer rainfall. ResultsThere was a significant longitudinal trend in the blue antelope mortality data, with juveniles and neonates declining in frequency from west to east. This suggests that calving occurred primarily in the winter rainfall zone, probably during the winter months when seasonal rains promoted the growth of C3 grasses. The summer drought and lack of adequate forage forced blue antelope to migrate east, in time with summer rainfall and the increased availability of C4 grasses. The migration route probably depended in part on reduced sea levels during glacial phases of the Pleistocene. Main conclusionsBlue antelope were probably migratory. Rising sea levels at the onset of the Holocene disrupted their migration routes, limited access to west‐coast calving grounds, and fragmented populations. Such disruption would have devastated the blue antelope population and contributed to its vulnerability to extinction. Blue antelope survived previous marine transgressions, however, suggesting that other factors played a role in its demise. Agricultural expansion early in the colonial era may have further disrupted migration routes and played an important role in its extinction.
... The large carbon isotopic difference between C 3 and C 4 primary producers has provided 1 of the most widely used and broadly applied dietary tracers in paleobiological study (Bocherens et al. 1996;Cerling et al. 1997Cerling et al. , 1998Fox and Koch 2004;Franz-Odendaal et al. 2002;Koch et al. 1998Koch et al. , 2004Latorre et al. 1997;Zazzo et al. 2000). In low and midlatitude grasslands where C 4 grasses are the dominant grass type today, d 13 C values of herbivore enamel record a dramatic increase in consumption of C 4 grasses during the late Miocene (protracted rise from 8 3 10 6 to 3 3 10 6 years ago- Cerling et al. 1997;Edwards et al. 2010;Tipple and Pagani 2007). ...
Article
Stable isotope analysis of fossil materials has become an increasingly important method for gathering dietary and environmental information from extinct species in terrestrial and aquatic ecosystems. The benefits of these analyses stem from the geochemical fingerprint that an animal's environment leaves in its bones, teeth, and tissues. Ongoing study of living mammals has found the stable isotopie composition of several light (hydrogen, carbon, nitrogen, oxygen, and sulfur) and even a few heavy (calcium and strontium) elements to be useful tracers of ecological and physiological information; many of these can be similarly applied to the study of fossil mammals. For instance, the carbon isotopie composition of an animal's tissues tracks that of the food it eats, whereas the oxygen isotopie compositions of the carbonate and phosphate in an animal's bones and teeth are primarily controlled by that of the surface water it drinks or the water in the food it ingests. These stable isotope proxies for diet and habitat information are independent of inferences based on morphological characters and thus provide a means of testing ecological interpretations drawn from the fossil record. As such, when well-preserved specimens are available, any dietary study of fossil species should seriously consider including this approach. To illustrate the potential benefits associated with applying these methods to paleontological research, a review of current work on the ecological and evolutionary history of fossil mammals through geochemical analysis is presented. After a brief introduction to issues associated with the preservation of stable isotopie information in soft and mineralized tissues, a series of case studies involving the application of stable isotope analysis to fossil mammal research is discussed. These studies were selected to highlight the versatility of this analytical method to paleontological research and are complemented by a discussion of new techniques and instrumentation in stable isotope analysis (e.g., laser ablation and compound-specific isotope ratio mass spectrometry, and calcium and clumped isotopes), which represent the latest advances in the extension of these geochemical tools to the paleontology of fossil mammals.
... Alternatively, uplift of the Himalayas and resultant intensification of the Indian Monsoon (9-6 Ma; Molnar et al., 1993) may have altered the seasonality of precipitation in the region with increased aridity driving a shift to almost exclusively C4 vegetation in the summer precipitation regime in Pakistan (Quade and Cerling, 1995), and a mixed C3 and C4 vegetation in East Africa (Cerling et al., 1997b;Feakins et al., 2005;figure 4.4). Elsewhere, at Langebaanweg, South Africa, C3 vegetation remained dominant in the diet of grazing mammals at 5 Ma (Franz-Odendaal et al., 2002). Changing precipitation regimes (linked to regional circulation patterns; figure 4.2) would explain why C4 vegetation did not uniformly expand across Africa between 8 and 6 Ma and may also explain the late Pliocene and Pleistocene increase in C4 vegetation in East Africa ( figure 4.4). ...
... La composición isotópica del bioapatito es función del oxígeno que entra y sale del cuerpo del animal (Bryant & Froelich, 1995; Bryant et al., 1996;)Palmqvist et al., 2003). Valores similares de 0 13 C han sido publicados por y por Odendaal et al. (2002) para los grandes mamíferos de inicios del Pleistoceno medio en Tighenif (Argelia) y del Plioceno inferior en Langebaanweg (Sudáfrica), respectivamente, indicativos en los ungulados pacedores de ambas localidades de una dieta exclusiva de herbáceas c3. _x . ...
... Throughout their tenure in Africa, sivatheres have exhibited varied dietary behaviors across time and space. Multiple lines of evidence indicate a mixed feeding diet of browse and C 4 grasses for the late Miocene or early Pliocene southern African taxon S. hendeyi (Franz-Odendaal et al. 2002;Franz-Odendaal and Solounias 2004), while its descendant, S. maurusium, was thought to have persisted as a browser until the early Pleistocene (Cerling et al. , 2015. Previously reported isotope data from the Turkana Basin and Olduvai Gorge documented the transition from a browsing to a grazing diet dominated by C 4 biomass in S. maurusium shortly after 2 Ma (van der Merwe 2013; Cerling et al. 2015). ...
Article
Full-text available
The giraffid fossils recovered from ~ 2.8–2.6 million year old (Ma) sediments from Lee Adoyta, Ledi-Geraru, Ethiopia, are described here. Sivatherium maurusium and Giraffa cf. G. gracilis are the two identified taxa, with the former being more abundant than the latter. We interpret this skew of relative abundance to be of paleoenvironmental significance, as Sivatherium is rare and Giraffa is common in the adjacent, but older sediments of the Hadar Formation at Hadar (~ 3.4 to 2.95 Ma), which was characterized by wooded and well-watered habitats through most of its sequence. Stable carbon isotope analyses show that Giraffa remained an obligate browser throughout the lower Awash Valley (LAV) sequence while Sivatherium underwent a dietary transition from a browser in the Hadar Formation to a grazer at Lee Adoyta. This dietary shift in Sivatherium reflects local environmental change through time in the LAV as open habitats spread during the late Pliocene. A compilation of isotopic data from other sites in eastern Africa shows that the LAV dietary shift in Sivatherium occurred roughly one million years earlier than in the Turkana Basin, Kenya, reflecting a spatiotemporally staggered expansion of C4 vegetation across eastern Africa.
... Alternatively, uplift of the Himalayas and resultant intensification of the Indian Monsoon (9-6 Ma; Molnar et al., 1993) may have altered the seasonality of precipitation in the region with increased aridity driving a shift to almost exclusively C4 vegetation in the summer precipitation regime in Pakistan (Quade and Cerling, 1995), and a mixed C3 and C4 vegetation in East Africa (Cerling et al., 1997b;Feakins et al., 2005;figure 4.4). Elsewhere, at Langebaanweg, South Africa, C3 vegetation remained dominant in the diet of grazing mammals at 5 Ma (Franz-Odendaal et al., 2002). Changing precipitation regimes (linked to regional circulation patterns; figure 4.2) would explain why C4 vegetation did not uniformly expand across Africa between 8 and 6 Ma and may also explain the late Pliocene and Pleistocene increase in C4 vegetation in East Africa ( figure 4.4). ...
Data
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The last 65 Ma of Earth's history, the Cenozoic, has been a time characterized by significant climate change. Major global changes included massive tectonic reorganization, a reduction in atmospheric pCO2 (Pagani et al., 1999; Pearson and Palmer, 2000), and a dramatic cooling of global climate, plunging the world from generally warm conditions into the repeated glacial-interglacial cycles of the ice age (Zachos et al., 2001). Deep-sea oxygen isotope records record global cooling of up to 8°C in the early Cenozoic, heralding the development of major ice sheets on Antarctica from 35 Ma, which further intensified the global cooling trend and cul-minated in cyclical Northern Hemisphere glaciation during the past 3 Ma (figure 4.1). Many events in global tectonics and high latitude climate had significant effects on Ceno-zoic climate evolution. These are well described elsewhere (e.g., Kennett, 1995; Denton, 1999; Zachos et al., 2001) and are summarized in figure 4.1. In this chapter, we focus on three revolutions in climate research that have dramatically altered our perception of global and African climate. First, the discovery that large magnitude climate events occurred abruptly, sometimes in as little as decades, has prompted high-resolution paleocli-mate reconstructions and new conceptions of climate dynamics, revealing significant climate variability at times that were previously thought to be quiescent (e.g., the Holocene). On longer timescales, high-resolution oxygen iso-tope stratigraphies have also revealed transient events in the early Cenozoic (Zachos et al., 2001). These discoveries have revolutionized theories of climate change and demonstrated the need for high-resolution reconstruction of climate vari-ability on 10 0 -to 10 5 -year timescales. Second, recent climate studies have revealed significant tropical climate variability. Modern observational climate data have indicated that the largest mode of global interan-nual climate variability is the El Niño Southern Oscillation (ENSO) in the tropical Pacific (Ropelewski and Halpert, 1987; Trenberth et al., 1998). Large amplitude tropical environ-mental variability has also been reconstructed in the paleo-climate record. In particular, revised estimates of tropical sea surface temperatures (SSTs) during global cool and warm events have revealed significant tropical sensitivity to global climate change (e.g., Pearson et al., 2001; Lea et al., 2003). Revised tropical SST reconstructions have implications both for local climate interpretations and for global dynamical predictions, leading to new perspectives on the nature of Cenozoic climate change. Third, the role of the tropics in global climate change has been reconceptualized. Rather than being a passive responder to changes in the high-latitude cryosphere, tropical climate variability may be at least partially decoupled from high-latitude climate. For example, there is considerable evidence that precessional variations in insolation may directly influ-ence the intensity of African precipitation, independent of high-latitude climate variability (Rossignol-Strick, 1983; Partridge et al., 1997; Denison et al., 2005). The tropics may even have driven global climate change. For example, ENSO generates global teleconnections that have been observed in the instrumental record (Cane and Zebiak, 1985; Cane and Clement, 1999), and evidence for tropical initiation of past global climate changes comes from both paleoclimate and modeling analyses (Linsley et al., 2000; Clement et al., 2001; Hoerling et al., 2001; Yin and Battisti, 2001). This chapter provides a synthesis of climate data from a tropical perspec-tive that offers new insights into aspects of Cenozoic African environmental change.
... Historical accounts of grazers in the renosterveld-dominated WRZ of the south-western Cape also suggest that a prevalence of C 4 grasses is not necessary for large-bodied grazers (Skead, 1987). Although the nature of prevailing photosynthetic pathways of grasses in the WRZ is contentious (e.g., Klein and Cruz-Uribe, 1991b;Franz-Odendaal et al., 2002;Stynder, 2009;Faith, 2011), ...
Article
The Howiesons Poort, characterised by sophisticated lithic technologies and evidence of innovative behaviours, was a significant cultural phase in southern Africa during Marine Isotope Stage 4. It also coincided with substantial palaeoenvironmental and possible demographic changes in the southern Cape of South Africa, especially with regards to the shifting palaeo-coastline off the Agulhas Bank. The newly-excavated Klipdrift Shelter in the southern Cape presents a rare opportunity to compare faunal, lithic and palaeoenvironmental evidence from a single Howiesons Poort site along the present-day southern coast of South Africa. Here, we use faunal data from Klipdrift Shelter to explore the relationship between occupational intensity, subsistence behaviour and environment in the southern Cape during the Howiesons Poort period. Our results suggest a shift from a mixed terrain/browse-dominated environment during the earlier Howiesons Poort to open grasslands in the mid-later Howiesons Poort. This environmental shift corresponds to potential changes in occupational intensity or frequency throughout the sequence with evidence of increased occupations associated with grassier environments. Aspects of the cultural sequence, for example raw material procurement strategies, may be associated with shifting environmental conditions. The faunal evidence suggests links between occupation, environment and prey selection at Klipdrift. This raises interesting questions about the interplay between population density and the environment of the southern Cape, and its influence on subsistence behaviour during Marine Isotope Stage 4.
... Temperature is a critical part of this equation, and the evidence for cooling during the late Miocene (Zachos et al. 2001) indicates the C 4 threshold would require even lower CO 2 levels ( fig. 6). Low temperatures likely account for the lack of C 4 expansion at higher latitudes or higher elevations during the late Miocene Quade et al. 1994;Franz-Odendaal et al. 2002). ...
... Stable light isotope analysis is a tool frequently used to examine the ecology of extant (e.g. Vogel, 1978; Koch et al., 1995; ; Sponheimer and Thorp, 2001; Sponheimer et al., 2003), and extinct animals (Koch et al., 1989; LeeThorp et al., 1989; Thackeray et al., 1990; Quade et al., 1992; Bocherens et al., 1996; MacFadden, 1998; Sharp and Cerling, 1998; Franz-Odendaal et al., 2002; Zazzo et al., 2002; Stanton Thomas and Carlson, 2004; Tü tken et al., 2004). Stable light isotope ratios in the tissues of living organisms track or record the isotopic composition of features of the environment in which an animal lives. ...
Article
The palaeoecology of the coeval Middle Triassic non-mammalian cynodonts, Diademodon and Cynognathus (Therapsida) remains poorly understood although their gross morphology has been studied intensively. Significant differences in their growth patterns suggest inherent biological differences, despite having inhabited similar environments. In this study, the palaeoecology of Cynognathus and Diademodon specimens were examined using intra-tooth stable carbon and oxygen isotope analyses of enamel carbonate. The resulting stable isotope patterns of Cynognathus and Diademodon were compared with that of Crocodylus niloticus and published mammalian tooth enamel data. Predictably, the non-mammalian cynodont d13C values fall within the expected range for C3 plant diets. Both d18O and d13C values of Diademodon are markedly more depleted than those of Cynognathus, suggesting that the former fed in shadier, damper areas, was nocturnal and/or depended more directly on environmental water. The seasonal amplitude reflected in the Cynognathus teeth is relatively low. However, high amplitude, directional d18O intra-tooth variations in the Diademodon teeth are comparable to, or higher than, those observed for extant mammalian and C. niloticus teeth from semi-arid, seasonal regions. This suggests that marked seasonality prevailed in the Karoo Basin during the Middle Triassic, and that Diademodon was sensitive to these variations. These isotopic differences between Diademodon and Cynognathus indicate differing responses to climatic fluctuations and reveal new insights into the palaeoecology of non-mammalian cynodonts.
... Carbon isotope analyses for fossil herbivore molars, for example, offer little evidence for C 4 grassland expansion in Langebaanweg. 47 On the other hand, mesowear of Eurygnathohippus cf. baardi 27 implies a grazing diet for this equid, and microwear of Sivatherium hendeyi 48 suggests mixed feeding for this giraffid. ...
Article
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Palaeoenvironmental reconstructions are important for understanding faunal changes in southern Africa during the Mio-Pliocene. This paper contributes to our knowledge of the vegetal context at Langebaanweg (Western Cape province, South Africa) around 5 Myr ago through the inference of bovid diets and their implications for specific habitats. Dental microwear data are presented for specimens (n = 100) representing at least eight species from 'E' quarry beds 3aS and 3aN and compared with data for nine living ruminant taxa (n = 59 individuals) with known differences in diet and habitat preferences. Molar facets were examined by white-light confocal microscopy, and microwear feature attributes were measured, recorded and compared between the living and extinct species, and between fossil samples from the two stratigraphic levels. Evidence for mixed feeding by the most common bovids in the earlier Bed 3aS suggests the presence of at least some graminoids during the initial deposition of the 'E' quarry sediments. Later Bed 3aN bovids probably preferred herbaceous monocotyledons, suggesting an even greater concentration of graminoids. These results are consistent with other palaeoecological indicators suggesting endemic fynbos vegetation in the Cape Province during the Early Pliocene, but also hint at possible changes at Langebaanweg between Bed 3aS and Bed 3aN times.
... The presence of one lineage in more arid winterrainfall climates (Leoserica) and one with summerrainfall climates (Hyboserica) is, according to the palaeoclimatic record, not explained by the latter in a straightforward manner: uplift of the Himalayas and resultant intensification of the Indian Monsoon (9-6 Mya; Molnar et al., 1993) have altered the seasonality of precipitation around the Indian Ocean with increased aridity driving a shift to almost exclusively C4 vegetation in the summer precipitation regime in Pakistan (Quade & Cerling, 1995) and a mixed C3 and C4 vegetation in East Africa (Cerling et al., 1997;Feakins et al., 2005). In the western parts of South Africa, C3 vegetation remained dominant at 5 Myr (Franz-Odendaal et al., 2002). Changing precipitation regimes (linked to regional circulation patterns) in concert with the Miocene/Pliocene uplift of the eastern escarpment (Partridge, 1997) could explain why C4 vegetation did not uniformly expand across Africa between 8 and 6 Mya and may also explain the Late Pliocene and Pleistocene increase in C4 vegetation in East Africa (Feakins & Demenokal, 2010). ...
Article
A taxonomic revision of Hyboserica uncovers an unexpected diversity of species from Southern African forest remnants. The work results in the description of a new genus, Leoserica gen. nov., a new combination, a new synonymy and 32 new species are described. The lectotypes of Serica capensis and Triodonta caffra are designated. The habitus and male genitalia of all revised species are illustrated. A species distribution map and an identification key to the species are provided. Phylogenetic analysis reveals a deep split into one very diverse eastern clade that is distributed north to Zimbabwe, and one western clade that is restricted to the fynbos of the Cape Region.
... However, there were local differences in this pattern, for example, the Lake Turkana region in Eastern Africa got drier earlier than surrounding areas, serving as a "species factory" of mammals adapted to increasingly open grassland environments . In South Africa, the shift to C4 grasses apparently happened later, as stable isotope record indicates at least locally purely C3 conditions throughout the Late Miocene in Langebaanweg (Franz-Odendaal et al. 2002). ...
Chapter
Large herbivorous mammals have a long history of adaptation to changing environmental circumstances. Many groups of mammalian herbivores started as omnivores and opportunistic browsers of fruits and other plant parts, later adapting to increasingly specialised leaf browsing, and finally to grazing as open grass-dominated environments spread following climatic cooling and drying during the Neogene. Changes in global climate led to vegetational changes in terrestrial ecosystems, which resulted in changes in the proportions of browsing and grazing species in the ungulate guilds. There is currently a range of proxy methods to assess diets and feeding ecology of large extinct herbivorous mammals, including dental microwear and mesowear analyses and stable isotope analyses. Together these methods have enabled an increasingly diverse and fine-scale understanding of the dietary variation of herbivorous mammals throughout the Cenozoic, providing a more detailed picture than traditional comparative ecomorphology approaches alone. This chapter will provide an up-to-date assessment of the analytical methods of determining the diet of extinct large herbivorous mammal taxa, and provide insights into changes in the assemblages of browsing and grazing mammals and how these relate to changes to climate and the evolution of different plant forms.
... Thus, during the Pliocene, the spread of C4 grasses happened in the context of grassy woodlands rather than in the context of open grassland landscapes. Further south, stable carbon-isotope evidence from Langebaanweg, South Africa, shows no evidence of C4 grasses at least until the early Pliocene, four million years ago (Franz-Odendaal et al. 2002). C4-photosynthesizing grasses of the family Andropogoneae, which today dominate in open grasslands with heavy grazing and frequent burning, probably became increasingly abundant during the late Miocene (Retallack 1992). ...
Chapter
The development of grassland ecosystems across most continents was a multistage process involving the appearance of open-habitat grasses in the Paleogene, the mid-late Cenozoic spread of C3 grass-dominated habitats, and, finally, the Late Neogene expansion of C4 grasses at tropical and subtropical latitudes. In addition, the timing of these evolutionary and ecological events varied across continents and between regions. The middle Miocene witnessed a climate optimum at a global scale, but, soon thereafter, beginning about 14 million years ago, a global cooling trend commenced that was accompanied by environmental change. This drop in global temperature resulted in the spread of more arid and seasonally dry conditions that, in turn, resulted in the expansion of increasingly open woodlands. Changes in resources also led to modifications in the distribution and abundance of mammalian herbivores, favoring forms with hypsodont teeth. In Europe, where humid climates generally persisted throughout the Neogene, the Iberian Peninsula was the first region to experience increasingly seasonal aridity in the early Miocene. Open environments under an arid climate remained confined to Southern Europe and only expanded into Northern Italy in the latest Miocene. The spread of aridity to this region is associated with the final stage of the Messinian Salinity Crisis. In Eastern Asia, generally humid conditions existed before the late middle Miocene but were replaced by a midlatitude arid belt in the late middle–late Miocene. The East Asian summer monsoon, an atmospheric circulation pattern of the present, only influenced the region later, with the beginning of eolian red clay deposition, sometime between seven and eight million years ago. A similar pattern is recorded elsewhere. Biomes changed from tropical forest to steppes across broad areas of southern South America during the early–middle Miocene. Hence, a general global pattern of vegetational turnover is witnessed in the Neogene. More open woodlands and/or grasslands appeared over all continental landmasses in response to changes from rather humid conditions to more seasonally dry, semiarid, and arid climates at various times during the Miocene. In this chapter, we will explore these vegetational changes to understand if they were accompanied by changes in faunal composition, reshaping the world’s biosphere.
... The presence of one lineage in more arid winterrainfall climates (Leoserica) and one with summerrainfall climates (Hyboserica) is, according to the palaeoclimatic record, not explained by the latter in a straightforward manner: uplift of the Himalayas and resultant intensification of the Indian Monsoon (9-6 Mya; Molnar et al., 1993) have altered the seasonality of precipitation around the Indian Ocean with increased aridity driving a shift to almost exclusively C4 vegetation in the summer precipitation regime in Pakistan (Quade & Cerling, 1995) and a mixed C3 and C4 vegetation in East Africa (Cerling et al., 1997;Feakins et al., 2005). In the western parts of South Africa, C3 vegetation remained dominant at 5 Myr (Franz-Odendaal et al., 2002). Changing precipitation regimes (linked to regional circulation patterns) in concert with the Miocene/Pliocene uplift of the eastern escarpment (Partridge, 1997) could explain why C4 vegetation did not uniformly expand across Africa between 8 and 6 Mya and may also explain the Late Pliocene and Pleistocene increase in C4 vegetation in East Africa (Feakins & Demenokal, 2010). ...
Article
A taxonomic revision of Hyboserica uncovers an unexpected diversity of species from Southern African forest remnants. The work results in the description of a new genus, Leoserica gen. nov., a new combination, a new synonymy and 32 new species are described. The lectotypes of Serica capensis and Triodonta caffra are designated. The habitus and male genitalia of all revised species are illustrated. A species distribution map and an identification key to the species are provided. Phylogenetic analysis reveals a deep split into one very diverse eastern clade that is distributed north to Zimbabwe, and one western clade that is restricted to the fynbos of the Cape Region.
... Furthermore, mammals exploiting subcanopy vegetation have negative d 13 C enamel values reaching À25& (Cerling et al., 2004). To sum up, such variations in d 13 C (from À25& to À9&) reflect a wide spectrum of present-day environments with C 3 vegetation from mid-latitude grasslands to equatorial forests to Mediterranean biomes (Quade et al., 1995;Sponheimer and Lee-Thorp, 1999;Franz-Odendaal et al., 2002;Cerling et al., 2003;Sponheimer et al., 2003;Wang et al., 2008;Kohn, 2010). ...
... Comparing these data to a series of average isotope values from sites elsewhere in Africa (Sponheimer & Lee-Thorp 2009), Matjhabeng differs from the predominantly browsing fauna of Langebaanweg (Franz-Odendaal et al. 2002), and indicates more extensive C 4 grasslands even than later sites such as Makapansgat and Sterkfontein. It thus appears that the Free State was dominated by grasslands from at least the later-early Pliocene. ...
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The early Pliocene is a relatively poorly understood period in southern Africa. Fossil deposits such as Langebaanweg (c. 5.0 Ma) and Makapansgat (c. 2.5 Ma) have each produced large and well-documented faunal assemblages, and it is clear that a significant turnover of fauna occurred between the early and late Pliocene respectively. However, the temporal separation between Langebaanweg and Makapansgat represents a significant gap in our knowledge of faunal composition and evolution in the Pliocene of southern Africa. In 2007 we began a programme of excavation at an early Pliocene locality referred to as Matjhabeng (formerlyVirginia) in the Free State of South Africa. With an estimated age of 4.0-3.5 Ma, this site represents a temporal and geographic intermediate between the better known sites to the north and south. It also represents the only well-documented, river-deposited Pliocene locality in the central interior of southern Africa. After three years of excavation, we have recovered a diverse fauna that includes fish, amphibians, reptiles, birds and mammals. Mammals range in size from rodents to mammoths, including an array of proboscideans, perissodactyls and artiodactyls, alongside rare carnivores.We report here on the macromammalian assemblage recovered to date. In total, we have recognized 29 taxa, including the oldest Ancylotherium and the oldest Megalotragus fossils in southern Africa. Some of the taxa from Matjhabeng are shared with Langebaanweg, and others with Makapansgat, confirming the intermediate status of this locality. Isotopic analysis reveals the earliest indication of extensive grasslands in South Africa, though these grasslands were part of an environmental mosaic that included significant woodland, and probable wetland, components.
... While divergence of major western clades may have been the result of vicariance operating during climatic shifts of the Plio- Pleistocene, the climatic environment has been relatively constant since that time. The winter rainfall zone (WRZ) which dominates the west is extremely stable, and has persisted for ca. 5 Myr, although its continental extent and overall intensity have likely shifted (Chase and Meadows, 2007; Franz-Odendaal et al., 2002). In contrast, the eastern CFR is within an aseasonal year-round rainfall zone (YRZ). ...
Article
The Cape Floristic Region (CFR) is well-known for its floral diversity, yet also contains a rich herpetofauna with >180 species, 28% of which are endemic. Recent studies conducted on CFR lizards indicated that phylogeographic patterns show some congruency, and that the western CFR shows higher overall diversity in the form of population and/or clade turnover. Here, we combine mitochondrial sequence data from two published (Bradypodion spp. and Agama atra) and one new dataset (Pedioplanis burchelli) to investigate whether geographic patterns of genetic diversity could be influenced by predicted climatic changes. We utilised Bayesian methodology and spatial genetic landscapes to establish broad-scale patterns and show that the western CFR is a contact zone for several clades in all three taxa, supporting the hypothesis of phylogeographic congruence. Current levels of gene flow are virtually zero between the western and eastern CFR. In the east, gene flow between populations is negligible at present but was probably stronger in the past given the present lack of strong genetic structure. Bioclimatic modelling predicted that climatically suitable areas within the CFR will decline for Bradypodion spp. and P. burchelli, with areas high in clade turnover loosing more climatically suitable areas than areas with low clade turnover. The models also predict that loss of climatic suitability may result in highly fragmented and patchy distributions, resulting in a greater loss of connectivity. In contrast, A. atra does not show significant climatic suitability losses overall, although it may experience localised losses (and gains). This species is not predicted to loose suitability in areas of high clade turnover. Thus, the incorporation of genetic data into climatic models has extended our knowledge on the vulnerability of these species given the predicted threat of landscape change.
Article
The dietary regimes of 15 ungulate species from the middle Pleistocene levels of the hominid-bearing locality of Elandsfontein, South Africa, are investigated using the mesowear technique. Previous studies, using taxonomic analogy, classified twelve of the studied species as grazers (Redunca arundinum, Hippotragus gigas, Hippotragus leucophaeus, Antidorcas recki, Homoiceras antiquus, Damaliscus aff. lunatus, Connochaetes gnou laticornutus, Rabaticerus arambourgi, Damaliscus niro, Damaliscus sp. nov., an unnamed “spiral horn” antelope and Equus capensis), one as a mixed feeder (Taurotragus oryx) and two as browsers (Tragelaphus strepsiceros and Raphicerus melanotis). Although results from mesowear analysis sustain previous dietary classifications in the majority of cases, five species were reclassified. Three species previously classified as grazers, were reclassified as mixed feeders (H. gigas, D. aff. lunatus and R. arambourgi), one previously classified as a grazer, was reclassified as a browser (the “spiral horn” antelope), and one previously classified as a mixed feeder, was reclassified as a browser (T. oryx). While current results broadly support previous reconstructions of the Elandsfontein middle Pleistocene environment as one which included a substantial C3 grassy component, the reclassifications suggest that trees, broad-leaved bush and fynbos were probably more prominent than what was previously thought.
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We describe the most complete postcranial remains of a pathological, large-bodied sabretooth from the Lower Pliocene site of Langebaanweg ‘E’ Quarry (South Africa). The skeleton consists of hind limb and vertebral elements that exhibit distinctive exostoses, osteophytes and eburnation. We performed a quantitative morphological comparison of the new postcranial remains found in Langebaanweg, with other Neogene and Quaternary sabretooth and non-sabretooth felids, consisting of the genera Amphimachairodus, Machairodus, Lokotunjailurus, Dinofelis, Panthera, Homotherium and Smilodon from several sites in Africa, Europe and North America, using principal component analysis and Mosimann transformations. Although the pathological deformation of the remains distorted some of the linear measurements, most of the analysed variables do not contain pathological features, and strongly indicate that the Langebaanweg sabretooth is morphologically closer to Machairodus aphanistus and Lokotunjailurus emageritus than it is to Amphimachairodus giganteus. This indicates that the remains could belong to an undetermined sabretooth species from the Langebaanweg locality. The observed pathologies in the foot and lumbar spine are consistent with diagnostic criteria for severe osteoarthritis (due to maturity), which would have limited limb mobility with severe consequences for hunting success
Article
The floral community along South Africa's southwest coast today is dominated by shrubby strandveld, renosterveld, and coastal fynbos vegetation. The grass family (Poaceae), represented primarily by C 3 taxa, is scarce by comparison. Nevertheless, grass has a long history along this coast, as indicated by the presence of ∼5-million-year-old C3 grass pollen and phytoliths in sediments at the fossil locality of Langebaanweg E Quarry. Because the pollen and phytoliths of other plant families, including fynbos, have also been found, it has been difficult to determine whether grass was scarce or abundant in this environment. In order to shed light on this issue, I analyzed the dental mesowear of the E Quarry bovids. Results indicate that only one (Simatherium demissum) of seven analyzed species was a grazer. These compare well with the results of a microwear texture analysis, which indicate that none of the seven analyzed species were obligate grazers. These two studies point strongly toward a heavily wooded environment and not one that was dominated by grass. Although a conventional dental microwear analysis did identify three out of seven E Quarry bovid species as grazers (Bed3aN Damalacra, Kobus subdolus, and S. demissum), only S. demissum probably actually was a grazer. I suggest that the grazer signal exhibited by the other two bovid samples indicate that these species were taking advantage of a spike in grass abundance, probably during the winter growth season.
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The existence of lignitic deposits (Knysna Formation) on the South African south coast, near to the town of Knysna has been recognised for more than a century. However, a combination of limited study and few natural exposures has meant that the age and stratigraphic position of the Knysna Formation are unclear, despite its potential as a palaeoenvironmental archive. We present a new suite of chronological, geochemical and palynological data obtained from a recently identified lignite exposure in this area. The lignite pollen assemblage is dominated by palms (Arecaceae), which are now locally extinct, and contains additional palynomorphs of tropical affinity, along with (moist-temperate) Podocarpus-type pollen, grasses, and herbaceous pollen types (e.g. Cliffortia-type, Asteraceae). Overall, the assemblage shows some commonalities with the Miocene Elandsfontein Formation in the Western Cape. The lignites are dominated by a diverse range of higher plant biomarkers, including abundant leaf wax lipids, as well as lignin monomers and leaf cuticle-derived macromolecular organic matter. All strongly indicate a terrestrial depositional setting, perhaps akin to contemporary palm swamps. A number of sesquiterpenoids imply the presence of gymnosperms, supporting observations from the pollen data and previously reported macro-fossil finds. The application of isothermal thermoluminescence techniques to coversands overlying the lignite produced a minimum age of similar to 1.7 Ma. Additional clues as to the likely age of the lignite are provided by compound-specific stable carbon isotope analyses of the leaf wax lipids. These are approximately 8 parts per thousand enriched relative to typical C(3) vegetation leaf waxes, and imply a potential contribution from C(4) vegetation. From this, an age post-dating the Oligocene may be inferred, and in conjunction with the site's geomorphic setting, an age post dating the middle Miocene is considered plausible. This is markedly younger than previous (Eocene) age estimates for the Knynsa Formation.
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Middle Miocene deposits at Maboko Island in the Nyanza Rift of Western Kenya (~15–14 Ma) have yielded a rich fossil mammalian record that documents a mid-Miocene faunal shift. Palaeoecological proxies for Maboko have previously been interpreted to indicate heterogeneous habitats, ranging from grassland to closed canopy forest and implicated in this turnover. Stable carbon and oxygen isotope data of fossil herbivore enamel from catarrhine-bearing deposits at Maboko were analyzed to reconstruct the nature of C3 vegetation (i.e., water-stressed or subcanopy), as well as determining if any C4 biomass, representative of more open woodland or grassland habitats, were consumed. Taxa sampled include representatives of ruminants, suoids, rhinocerotids, and proboscideans. δ¹³Cenamel and δ¹⁸Oenamel values of Maboko fossil herbivores indicate foraging strategies consistent with a C3 dominated ecosystem, exhibiting a range of δ¹³Cenamel signatures similar to those of extant browsing herbivores foraging in mosaics of open forest/woodland habitats. Within the Maboko sequence, isotopic evidence indicates alternating environments based on variable dietary spectra associated with discrete fossiliferous units within the succession. Relative to other stratigraphic beds, isotopic signals of herbivore enamel from Bed 5b, for example, reflect more closed woodland/forest foraging. The overall ~4‰ range of δ¹³Cenamel values from Maboko (−14.1‰ to −10.2‰) is statistically similar to δ¹³Cenamel values from the slightly younger middle Miocene site of Fort Ternan and is consistent with faunal and paleosol evidence from Maboko suggesting ecological variability. However, the isotopic evidence from Maboko indicates that environmental variability is more constrained than previously reconstructed, instead ranging from more open canopy forest to open woodland habitats, albeit with some spatial and temporal heterogeneity. Closed canopy forest plants and C4 biomass were not detectable as dietary components for any herbivores sampled thus far; nor was there evidence of significantly water-stressed C3 vegetation (possibly C3 grasses) being consumed.
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It has long been proposed that pre-modern hominin impacts drove extinctions and shaped the evolutionary history of Africa’s exceptionally diverse large mammal communities, but this hypothesis has yet to be rigorously tested. We analyzed eastern African herbivore communities spanning the past 7 million years—encompassing the entirety of hominin evolutionary history—to test the hypothesis that top-down impacts of tool-bearing, meat-eating hominins contributed to the demise of megaherbivores prior to the emergence of Homo sapiens . We document a steady, long-term decline of megaherbivores beginning ~4.6 million years ago, long before the appearance of hominin species capable of exerting top-down control of large mammal communities and predating evidence for hominin interactions with megaherbivore prey. Expansion of C 4 grasslands can account for the loss of megaherbivore diversity.
Article
This study investigates the mid-Pleistocene paleoenvironment and dietary behaviour of ancient herbivores in the South African central interior, today part of the semi-arid Kalahari savanna. Analyses were undertaken of carbon (δ¹³C) and oxygen (δ¹⁸O) stable isotopes in tooth enamel carbonate of twelve fossil herbivore species from Layers 4b and 4a, associated with Earlier Stone Age (ESA) and transitional ESA-Middle Stone Age (Fauresmith) industries respectively, at the archaeological site of Kathu Pan 1. The data are compared with other early to mid-Pleistocene herbivore assemblages located in the central interior, namely Cornelia-Uitzoek, Wonderwerk Cave and the Florisbad Spring. Results indicate that the median δ¹³C values for all ungulate taxa at Kathu were >-4‰, indicating predominantly C4 based diets, although in certain taxa, some individuals included a significant C3 component in their diet. The δ¹⁸O values of most of species at Kathu were relatively low, suggesting a cooler and/or wetter climate. Carbon isotope evidence for C4 dominated habitats at Kathu, but with a larger C3 component amongst grazers than today, resembles the other early to mid-Pleistocene assemblages in the region. Similarly, δ¹⁸O values for Kathu supplement existing evidence that the region was substantially wetter than in modern times.
Chapter
That humans originated from Africa is well-known. However, this is widely regarded as a chance outcome, dependant simply on where our common ancestor shared the land with where the great apes lived. This volume builds on from the 'Out of Africa' theory, and takes the view that it is only in Africa that the evolutionary transitions from a forest-inhabiting frugivore to savanna-dwelling meat-eater could have occurred. This book argues that the ecological circumstances that shaped these transitions are exclusive to Africa. It describes distinctive features of the ecology of Africa, with emphasis on savanna grasslands, and relates them to the evolutionary transitions linking early ape-men to modern humans. It shows how physical features of the continent, especially those derived from plate tectonics, set the foundations. This volume adequately conveys that we are here because of the distinctive features of the ecology of Africa.
Chapter
That humans originated from Africa is well-known. However, this is widely regarded as a chance outcome, dependant simply on where our common ancestor shared the land with where the great apes lived. This volume builds on from the 'Out of Africa' theory, and takes the view that it is only in Africa that the evolutionary transitions from a forest-inhabiting frugivore to savanna-dwelling meat-eater could have occurred. This book argues that the ecological circumstances that shaped these transitions are exclusive to Africa. It describes distinctive features of the ecology of Africa, with emphasis on savanna grasslands, and relates them to the evolutionary transitions linking early ape-men to modern humans. It shows how physical features of the continent, especially those derived from plate tectonics, set the foundations. This volume adequately conveys that we are here because of the distinctive features of the ecology of Africa.
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The origin of the African hominoid clade is a matter of current debate, with one hypothesis proposing that chimpanzees, humans, and gorillas originated in tropical Africa, while another suggests they originated in Eurasia. Support for the latter hypothesis includes biogeographical patterns inferred from the fossil record and proposed Miocene hominoid phylogenetic relationships. The absence of fossil apes from the African Late Miocene has been used as evidence that crown hominoids were not present in Africa during this period. An alternative explanation for the paucity of these hominoids is that biases in collection and preservation have affected the African Miocene fossil record. A survey of currently known African Later Miocene sites and their faunas shows that these sites generally do not contain hominoids because of small sample sizes, poor preservation, or inappropriate habitat sampling. These preservation biases have important implications for evaluating the origins of the Homininae. To cite this article: S.M. Cote, C. R. Palevol 3 (2004).
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The exceedingly rich middle Pleistocene mammalian fauna from the classic Ensenadan Tarija basin in southern Bolivia contains a diversity of medium to large-bodied herbivores consisting of both endemic (†Toxodontia, †Litopterna, Xenarthra) and immigrant (Rodentia, Proboscidea, Perissodactyla, and Artiodactyla) taxa. In order to characterize feeding ecology and niche differences, a suite of morphological characters was measured for each of 13 species of herbivorous mammals from the Pleistocene of Tarija; these were combined with carbon isotopic results from tooth enamel. (The Xenarthra were excluded from this study because they lack tooth enamel.) Several different bivariate and multivariate combinations of characters can be used to characterize the feeding adaptations, niches, and guild composition of the Tarija mammalian herbivores. During the Pleistocene the browsing guild in the Tarija basin is interpreted to include the tapir ( Tapirus tarijensis ), extinct llama ( Palaeolama weddelli ), peccary ( Tayassu sp.), and deer ( Hippocamelus sp.). The mixed-feeding guild included two horse species ( Hippidion principale and Onohippidium devillei ), litoptern ( Macrauchenia patachonica ), and capybara ( Neochoerus tarijensis ). The grazing guild included the numerically dominant horse ( Equus insulatus ), two lamine species ( Lama angustimaxilla and cf. Vicugna, provicugna ), notoungulate ( Toxodon platensis ), and gomphothere proboscidean ( Cuvieronius hyodon ). The grazing guild has the widest range of body sizes relative to the two other guilds. Closely related sympatric species within the Equidae and Camelidae differentiate their niches from one another using a combination of body size, feeding ecology, and probably local habitat. Most of the paleoecological reconstructions resulting from this combined morphological and isotopic analysis corroborate previous studies based primarily on morphology; there are, however, some notable surprises.
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The only antelopine species found today in southern Africa is the springbok, Antidorcas marsupialis. However, a close relative, A. bondi, was abundant and widespread during the Late Pleistocene. This animal died out at the beginning of the Holocene, ca. 7000 years ago. In a recent study of Florisbad fossil mammals, it was proposed that the extinct springbok was an exclusive grazer on the basis of its specialized dental features, in contrast to the modern springbok, which is a mixed feeder. We provide evidence in support of this hypothesis from stable carbon isotopic analysis of fossil and modern sprinbok teeth. The results are also in accordance with the interpretation that A. bondi coexisted with a wide range of larger-bodied grazing ungulates in a system similar to the grazing succession described for the Serengeti in East Africa.
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The diet of extant elephants (Loxodonta in Africa, Elephas in Asia) is dominated by C3 browse although some elephants have a significant C4 grass component in their diet. This is particularly noteworthy because high-crowned elephantid cheek teeth represent adaptation to an abrasive grazing diet and because isotopic analysis demonstrates that C4 vegetation was the dominant diet for Elephas in Asia from 5 to 1 Ma and for both Loxodonta and Elephas in Africa between 5–1 Ma. Other proboscideans in Africa and southern Asia, except deinotheres, also had a C4-dominated diet from about 7 Ma (when the C4 biomass radiated in tropical and subtropical regions) until their subsequent extinction.
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Stable carbon isotope analysis is now an established tool for investigating the diets of fossil taxa, but carbon isotopes provide us with limited information about an animal's ecology. Recent research suggests that mammalian oxygen isotope compositions might also prove profitable sources of ecological information. If we are to exploit this resource, however, we must improve our nascent understanding of oxygen isotope compositions within modern foodwebs. To this end, we have analyzed the oxygen and carbon isotope compositions of nine ecologically diverse, sympatric taxa from Morea Estate, Mpumalanga Province, South Africa. These data show that the Morea Estate faunivores are depleted in 18O compared to herbivores, and among the herbivores, frequent drinkers are relatively depleted in 18O. While more research is needed to address the mechanisms for and universality of these patterns, these results show oxygen isotope analysis to be a promising avenue of paleoecological research.
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The development of savanna-type grasslands is a relatively recent phenomena in East Africa. The stable carbon isotopic composition of paleosol carbonates from fossil localities in East Africa show that C 4 vegetation was present by about 8-9 Ma but made up only a relatively small proportion of the total biomass. Although the proportion of C 4 vegetation increased in the Pliocene and Pleistocene there is no evidence for the development of virtually pure C 4 grasslands, as is characterized by tropical grasslands today, until Middle Pleistocene times. This has important implications concerning the evolution of mammals in Africa, including hominids.
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The carbon. and oxygen isotope composition of carbonate in enamel hydroxylapatite can provide information on photosynthetic pathways of plants at the base of food webs, and on hydrological conditions. Retrieval of palaeoenvironmental information from isotopic composition of vertebrate fossils is complicated by potential diagenetic overprinting. In this study alteration has been assessed by examining the extent to which expected biological carbon and oxygen isotope patterns are disrupted in fossils of species whose diets cart be independently predicted by other criteria. The biological patterns used are 1) the differences in carbon, isotope composition between grazers and browsers, and 2) the differences in oxygen isotope composition between hippopotamus and terrestrial herbivores. Results obtained on, enamel samples from Tighenif (Algeria, approximate to 700,000 yr), Melka-Kunture (Ethiopia, 0.7-1.5 myr), and Anabo Koma (Djibouti, approximate to 1.6 myr) suggest that in vivo carbon and oxygen isotope compositions are preserved in most cases. Moreover, in all three regions, modern, patterns of C-3 versus C-4 grass dominance were present within the Pleistocene.
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Dietary adaptations of early hominids are generally understood to have played a crucial role in hominid evolution. The dietary habits of Australopithecus robustus are of special interest because the robust masticatory apparatus and characteristic dental features point to a distinctive dietary niche. Suggestions have ranged anywhere between carnivory and specialist herbivory, but current consensus has focused mainly on small hard items within the context of a vegetarian diet, and more particularly, frugivory. Few studies have challenged this perspective, although the results of a recent Sr/Ca study of A. robustus at Swartkrans were found to be inconsistent with herbivory. Here we address the question of A. robustus diet using 13C/12C ratio analysis of structural carbonate in tooth enamel, which has been shown to retain biogenic isotopic composition over long periods, contra earlier arguments based on bone apatite. Results for A. robustus, compared with other fauna from Swartkrans, show a mixed diet including both C3 and C4 foods. Since the C4 contribution must derive from consumption of grass or grazing animals, the data do not support either a specialist frugivorous or graminivorous niche for A. robustus; rather, they suggest a more generalized or omnivorous diet.
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The applicability of rapid and precise laser probe analysis of tooth enamel for {delta}{sup 18}O has been verified, and the method has been applied to different modern herbivores in East Africa. Sampling and pretreatment procedures involve initial bleaching and grinding of enamel to <75 {mu}m, and elimination of adsorbed water and organic compounds with BrF{sub 5}. Typical analytical reproducibilities for 0.5-2 mg samples are {+-}0.08{per_thousand} ({+-} 1{sigma}). Chemical and spectroscopic characterization of pretreated but unanalyzed samples show no alteration compared to fresh enamel. Solid reaction products are nearly pure CaF{sub 2} with little evidence for residual O{sub 2}. Because laser probe fluorination extracts oxygen from all sites in the apatite structure (phosphate, structural carbonate, and hydroxyl), only unaltered tooth enamel ( >95% apatite) can be analyzed reliably. Different East African herbivores exhibit previously unsuspected compositional differences. Average enamel {delta}{sup 18}O values (V-SMOW) are approximately: 25{per_thousand} (goat). 27{per_thousand} (oryx), 28{per_thousand} (dikdik and zebra), 29{per_thousand} (topi), 30{per_thousand} (gerenuk), and 32{per_thousand} (gazelle). These compositions differ from generalized theoretical models, but are broadly consistent with expected isotope effects associated with differences in how much each animal (a) drinks, (b) eats C3 vs. C4 plants, and (c) pants vs. sweats. Consideration of diet, water turnover. and animal physiology will allow the most accurate interpretation of ancient teeth and targeting of environmentally-sensitive animals in paleoclimate studies. 66 refs., 2 figs., 2 tabs.
Article
Medium- to large-bodied mammalian herbivores are taxonomically diverse and comprise a large component of the highly fossiliferous Neogene terrestrial sedimentary sequence from Florida. In order to reconstruct herbivore paleodiets and community paleoecology as well as understand climate and ecosystem change, 112 pristine tooth enamel samples were analyzed for at least 12 families and 26 genera within the orders Proboscidea, Perissodactyla, and Artiodactyla. These samples are from 17 localities and seven time horizons of late Miocene (Hemphillian) through late Pleistocene (Rancholabrean) age and between about 9.5 Ma to 100,000 yrs ago. Stable carbon isotopic analyses indicate that during the late Miocene local terrestrial communities and herbivore paleodiets consisted exclusively, or predominantly, of C3 plants, e.g., mean tooth enamel δC value is −11.9%o from the 9.5 Ma level. During the latest Miocene-early Pliocene (after 7 Ma) there is a shift in mean δC values of tooth enamel to −7.0%o (4.5 Ma level). This shift appears to correspond to other late Miocene δC shifts reported elsewhere in terrestrial and oceanic sedimentary sequences. On land, this shift is interpreted to represent the spread of isotopically more positive C4 grasses and probable change in diet from predominantly C3 to mixed C3/C4 plant foodstuffs. In general, the δC data reported here indicate that within the Florida sequence: (1) some families have remained predominantly browsers (Mammutidae, Tapiridae, Camelidae, Palaeomerycidae, and Cervidae); (2) some are predominantly C4 grazers (Elephantidae, Bovidae); (3) others consisted of mixed C3/C4 diets (Amebelodontidae, Gomphotheriidae, Equidae, Rhinocerotidae); and, based also on modern diets, (4) the isotopically intermediate peccaries (Tayassuidae) may have fed on CAM succulents. While these results generally confirm previous paleodietary hypotheses based on relative crown height, there also are some notable surprises in light of the stable carbon isotopic analyses.
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The objectives of this synthesis are (1) to review the factors that influence the ecological, geographical, and palaeoecological distributions of plants possessing C4 photosynthesis and (2) to propose a hypothesis/model to explain both the distribution of C4 plants with respect to temperature and CO2 and why C4 photosynthesis is relatively uncommon in dicotyledonous plants (hereafter dicots), especially in comparison with its widespread distribution in monocotyledonous species (hereafter monocots). Our goal is to stimulate discussion of the factors controlling distributions of C4 plants today, historically, and under future elevated CO2 environments. Understanding the distributions of C3/C4 plants impacts not only primary productivity, but also the distribution, evolution, and migration of both invertebrates and vertebrates that graze on these plants. Sixteen separate studies all indicate that the current distributions of C4 monocots are tightly correlated with temperature: elevated temperatures during the growing season favor C4 monocots. In contrast, the seven studies on C4 dicot distributions suggest that a different environmental parameter, such as aridity (combination of temperature and evaporative potential), more closely describes their distributions. Differences in the temperature dependence of the quantum yield for CO2 uptake (light-use efficiency) of C3 and C4 species relate well to observed plant distributions and light-use efficiency is the only mechanism that has been proposed to explain distributional differences in C3/C4 monocots. Modeling of C3 and C4 light-use efficiencies under different combinations of atmospheric CO2 and temperature predicts that C4-dominated ecosystems should not have expanded until atmospheric CO2 concentrations reached the lower levels that are thought to have existed beginning near the end of the Miocene. At that time, palaeocarbonate and fossil data indicate a simultaneous, global expansion of C4-dominated grasslands. The C4 monocots generally have a higher quantum yield than C4 dicots and it is proposed that leaf venation patterns play a role in increasing the light-use efficiency of most C4 monocots. The reduced quantum yield of most C4 dicots is consistent with their rarity, and it is suggested that C4 dicots may not have been selected until CO2 concentrations reached their lowest levels during glacial maxima in the Quaternary. Given the intrinsic light-use efficiency advantage of C4 monocots, C4 dicots may have been limited in their distributions to the warmest ecosystems, saline ecosystems, and/or to highly disturbed ecosystems. All C4 plants have a significant advantage over C3 plants under low atmospheric CO2 conditions and are predicted to have expanded significantly on a global scale during full-glacial periods, especially in tropical regions. Bog and lake sediment cores as well as pedogenic carbonates support the hypothesis that C4 ecosystems were more extensive during the last glacial maximum and then decreased in abundance following deglaciation as atmospheric CO2 levels increased.
Article
Palynological and lithological studies were carried out on a section of clays of the Elandsfontyn Formation in the Langebaanweg area. The pollen assemblages suggest a Middle Miocene age for these clays which is supported by fossil faunal evidence in the overlying gravel member of the Late Miocene “Saldanha” Formation. The pollen sequence indicates the retrogressive succession of subtropical — tropical gallery forest to dominant palm vegetation and finally to marsh. These changes are clearly related to the lithological evidence for the progressive lateral northward migration of the palaeo-Berg River. It is possible that the Middle Miocene global high sea-level cycle may have influenced these palaeoenvironmental changes.