Palaeo-Agulhas Plain Research Articles

Drivers of large mammal distribution: an overview and modelling approach for palaeoecological reconstructions of extinct ecosystems

Abstract One of the primary goals of the palaeosciences is to produce robust understandings of palaeoecologies of extinct ecosystems. The time has arrived where such palaeoecologies can be significantly improved—agent-based models (ABMs) that synthesize our modern understandings of animal ecology with past conditions provide a unique opportunity for this. The Palaeo-Agulhas Plain (PAP), a now submerged landscape off the south coast of South Africa, formed a novel ecosystem during the lower sea levels of the Pleistocene. Here we provide a review of the utility of ABMs for understanding herbivores in prehistoric environments using the Paleoscape Model. The Paleoscape Model is fortunate to have features models of climate, geology and vegetation upon which we can understand how herbivores used the PAP environment. To incorporate aspects of herbivore behaviour and habitat suitability into the model requires analogies from extant systems. In addition to reconstructions of the availability of resources and associated risks, data on herbivore behaviour and physiology are imperative to our understanding of these systems. Behaviour, driven by changes in the environment, is interpreted by species, leading to selection of suitable habitats ultimately driving the herbivore’s decisions within ABMs. Finally, we discuss herbivore integration into these models that can be used in numerous other scenarios (past, present and future).

Tracking the extinct giant Cape zebra (Equus capensis) on the Cape south coast of South Africa

AbstractThe giant Cape zebra (Equus capensis) is one of the extinct Quaternary large mammal species of southern Africa, and the largest equid from the Quaternary of Africa. Twenty-six Pleistocene equid tracksites have been identified in aeolianites on the Cape south coast of South Africa. An age range of 161 ± 12 ka to 43 ± 4 ka has been established through Optically Stimulated Luminescence. More than half of the sites contain large-equid tracks, representing the first ichnosites attributed to E. capensis. Smaller equid tracks may have been registered by the quagga (E. quagga quagga). The abundance of E. capensis tracksites on the Cape south coast contrasts with the paucity of body fossils of the species from the region, contrasting with the impression obtained from the body fossil record that E. capensis was predominantly a west coast species in the region. The new data illustrate the capacity of the body fossil and trace fossil records to complement each other. The loss of suitable habitat provided by the Palaeo-Agulhas Plain was probably a contributing factor in the extinction of this large-bodied grazer. A long trackway at Driefontein, attributed to E. capensis, adds to a sparse global record of fossil horse trackways.

Using functional groups to predict the spatial distribution of large herbivores on the Palaeo‐Agulhas Plain, South Africa, during the Last Glacial Maximum

ABSTRACTThroughout much of the Quaternary, lower sea levels in the southern Cape of South Africa exposed a different landscape to what we see today, the Palaeo‐Agulhas Plain (PAP). The PAP was dominated by large‐bodied and gregarious grazing species contrasting with the small‐bodied predominantly solitary species we find in the region today. The distribution of these herbivores would likely have been driven by similar drivers we see in contemporary herbivore ecology. Importantly, the occurrence of early humans and their associated technology would have also influenced the probability of herbivores occurring in an area. Here we create a predictive model for large herbivores using probability of occurrence of functional grouping in relation to environmental drivers and humans. We show how early humans influenced the distribution of large herbivores on the PAP alongside other environmental drivers. In the fynbos biome, probability of occurrence was highest for the medium‐sized social mixed feeders’ functional group in the thicket for small non‐social browsers, large browsers, and non‐ruminants and in grasslands for water‐dependent grazers. In our models, human influence affected functional groups to varying degrees but had the strongest effect on medium‐sized social mixed feeders.

Morphology of Pleistocene elephant tracks on South Africa's Cape south coast and probable elephant trunk-drag impressions

AbstractAeolianites and cemented foreshore deposits on South Africa's Cape south coast have the capacity to record and preserve events that transpired on them when they were composed of unconsolidated sand. Thirty-five Pleistocene elephant tracksites have been identified along this coastline. This abundance of sites along what was the margin of the vast Palaeo-Agulhas Plain allows for an appreciation of the forms that elephant tracks and traces can take in the context of the global proboscidean track record. They point to a significant regional elephant presence from Marine Isotope Stage (MIS) 11 (~400 ka) through MIS 5 (~130–80 ka) to MIS 3 (~35 ka) and also indicate repeated use of certain dune areas. They buttress Holocene and historical evidence that elephants made use of open areas in the region, and that the remaining “Knysna elephants” retreated into dense afrotemperate forest for protection in recent centuries. Analogies can be drawn between Pleistocene elephant tracks and Mesozoic dinosaur tracks, and some of the Cape south coast elephant tracks are among the largest Cenozoic (and hence, Quaternary) tracks ever to be described. A newly identified tracksite in this area may provide the first reported evidence of elephant trunk-drag impressions.

Retrodicting large herbivore biomass for the last glacial maximum on the Palaeo-Agulhas Plain (South Africa) using modern ecological knowledge of African herbivore assemblages and rainfall

AbstractHerbivore distribution throughout Africa is strongly linked to mean annual precipitation. We use that relationship to predict functional group composition of herbivore communities during the last glacial maximum (ca. 21 ka) on the now submerged Palaeo-Agulhas Plain (PAP), South Africa. We used metabolic large herbivore biomass (MLHB) from 39 South African protected areas, in five functional groups (characterized by behavior and physiology). We examined how modern factors influenced MLHB and considered the effects of biome, annual rainfall, percentage winter rainfall, and protected area size. Overall, biome was the most important factor influencing the relationship between MLHB and rainfall. In general, MLHB increased with rainfall, but not for the grassland biome. Outside grasslands, most functional groups’ metabolic biomass increased with increasing rainfall, irrespective of biome, except for medium-sized social mixed feeder species in savanna and thicket. Protected area size was influential for medium-sized social mixed feeders and large browsers and rainfall influenced medium-sized social mixed feeders, offering some perspectives on spatial constraints on past large herbivore biomass densities. These results improve our understanding of the likely herbivore community composition and relative biomass structure on the PAP, an essential driver of how early humans utilized large mammals as a food resource.

The Palaeo-Agulhas Plain: Temporal and spatial variation in an extraordinary extinct ecosystem of the Pleistocene of the Cape Floristic Region

At the height of its extent, during strong glacials, the Palaeo-Agulhas Plain (PAP, south coast of South Africa) was the size of Ireland, sometimes doubling the size of the extant Cape Floristic Region (CFR). During strong interglacial climates, the PAP was mostly submerged and its ecosystems destroyed or restricted to small slivers. Scientists have largely ignored the PAP, presumably because it is submerged. We argue the PAP contributed to the diversification of the mega-diverse CFR biota and was the most productive foraging habitat available to the early modern humans that inhabited the famous archaeological sites along the current coast. We synthesize the palaeo-archival evidence and modeling results from this special issue, and other results, and propose a general model for the Last Glacial Maximum PAP, and offer suggestions as to conditions during marine isotope stages (MIS) 6 and 4. Unlike the region today, the PAP included abundant nutritious grassland, savanna-like floodplains, numerous wetlands, and a soft and highly dynamic coastline. Grasslands dominated the northern plains and fynbos shrublands the southern plains, both cut by broad meandering rivers with extensive floodplain woodlands and grasslands. The high productivity of the northern sector PAP supported a diverse plains fauna and rich habitats for humans living along its northern fringe, and during MIS 4 they had access to large ungulates on the grasslands, coastal resources, and plant foods from the plain and interior. The Holocene and historical contact period provide our current model of human and ecological conditions in the CFR region, but should be interpreted as a low-resource outlier.

An isotopic test of the seasonal migration hypothesis for large grazing ungulates inhabiting the Palaeo-Agulhas Plain

The Greater Cape Floristic Region of South Africa was critical to the evolution of early modern humans (Homo sapiens) during the Pleistocene. The now submerged continental shelf formed its own ecosystem, the Palaeo-Agulhas Plain (PAP), where early humans lived and foraged. Grazing animals living on the plain might have migrated east and west tracking seasonally varying rains—a hypothesis tested here by examining δ13C and δ18O of serially-drilled teeth from seven ungulate genera: Alcelaphus, Connochaetes, Antidorcus, Redunca, Damaliscus, and Hippotragus. Modern observations and paleoecological reconstructions indicate that summer rainfall areas to the east have more C4 grasses while the winter rainfall areas to the west have more C3 grasses, and that summer and winter rains differ in δ18O. Thus, we analyze δ13C and δ18O preserved in herbivore teeth from the site of PP30 (a hyena den dating to ∼151 ka) to infer diet and water source throughout tooth formation. On a generic level, none of the samples exhibit δ13C or δ18O values that differ significantly from a taxon that likely foraged locally through the year (Southern reedbuck, Redunca arundium). Overall, results indicate that the PAP could support herbivore populations year-round without substantial migration, providing an ecosystem ideal for human inhabitants.

Micromammal and macromammal stable isotopes from a MIS 6 fossil hyena den (Pinnacle Point site 30, south coast, South Africa) reveal differences in relative contribution of C4 grasses to local and regional palaeovegetation on the Palaeo-Agulhas Plain

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.

Return rates from plant foraging on the Cape south coast: Understanding early human economies

The Cape south coast of South Africa has attracted significant archaeological research because it hosts the earliest evidence of human cultural and material complexity. Furthermore, the now-submerged Palaeo-Agulhas Plain provided habitat and resources for humans during the emergence of modern behavioural traits. Using a human behavioural ecology approach—optimal foraging theory—we sought to understand how this region’s flora may have contributed to the existence of early humans along the Cape south coast. We conducted monthly plant food foraging excursions over a two-year period in the seven main vegetation types that occur within the study area. Two (rarely three) local inhabitants harvested indigenous edible plant parts in 30-min foraging bouts. A total of sixty-eight participants (of Khoe-San descent), with knowledge on edible indigenous flora, contributed to 451 bouts. This study thus provides the largest published actualistic dataset on plant foraging returns. Without any prior knowledge of spatial resource density, the foragers harvested a total of 90 different edible species and obtained an overall mean (±SD) hourly return of 0.66 ± 0.45 kg/h or 141 ± 221 kcal/h. Apart from renosterveld, where winter returns were higher compared to summer, all other vegetation types showed no seasonal difference in return rates. Plants, therefore, most likely played an important role as fall-back or reliable staple food in the Cape south coast. Edible resources were unevenly distributed spatially, with calorific returns ranging from 0 to 2079 kcal/h, with fewer — but productive — high-density areas or “hotspots”. Sand fynbos (246 ± 307 kcal/h) and dune fynbos-thicket mosaic (214 ± 303 kcal/h) yielded significantly higher returns than other vegetation types (except for riparian). Prior knowledge of such hotspots, both within and amongst vegetation types, would have offered a significant foraging advantage. Finally, we provide the first quantified evidence that forager-extracted plant returns are significantly higher—nearly three times higher—in recently burnt sand and limestone fynbos vegetation. This supports Deacon’s hypothesis that hunter-gatherers could have improved their return rates by purposely burning Cape vegetation (i.e. “fire-stick farming”) to give them access to temporally abundant geophyte "hotspots". We also demonstrate the current challenges when comparing plant return rates across different studies and discuss the benefits of using participants that are not full-time hunter gatherers.

Migration of Pleistocene shorelines across the Palaeo-Agulhas Plain: Evidence from dated sub-bottom profiles and archaeological shellfish assemblages

Intertidal zones on shorelines are geologically complex features of the coastal plain, shaped by heterogeneous substrate lithologies. Palaeocoastlines have been heavily modified by sea-level change, ocean currents, wind, waves and swell. Rocks and sediments along intertidal zones create rich habitats for biogenic forms including shellfish, which are highly sensitive to subtle variations in underlying lithology. Here, we assess Pleistocene shoreline migrations on the south coast of South Africa in relation to fluctuating sea-levels and changes in sediment supply. The study area extends from Still Bay to Mossel Bay, South Africa, with a particular focus on Pinnacle Point. Our goal is to better understand the changes to the intertidal zone along these palaeocoastlines and how this may have affected marine resources available to early humans. We interpret marine geological records at select time slices along sub-bottom profiled transects that run perpendicular to the coast. We describe the character of specific shorelines to establish expectations of coastline character which we then compare to archaeological records at Pinnacle Point. We base our interpretations on (1) significant events in Pleistocene glacio-eustatic and depositional records, such as widespread deposition of coastal sand dunes at ∼90, ∼74 and ∼50 ka [MIS 5e–MIS 4], and (2) empirical evidence from high-resolution records of shellfish assemblages at the archaeological sites of PP13B and PP5-6. We demonstrate a prevalence of dissipative beaches and mixed coasts on Pleistocene sea-level lowstands on the coast of the Palaeo-Agulhas Plain. This differs significantly from the modern coastline with its significance of rocky shorelines.

Plant diversity of Holocene dune landscapes in the Cape Floristic Region: The legacy of Pleistocene sea-level dynamics

Coastal dune landscapes are subject to harsh environmental conditions and, owing to Pleistocene sea-level fluctuations, comprise small, fragmented features. These environments present several challenges for plant colonization and persistence, and dune floras are therefore likely to be species-poor but endemic-rich. Here, we explore an explicitly historical hypothesis — the Pleistocene disturbance hypothesis — to explain patterns of plant diversity on Holocene dunes of the Cape Floristic Region (CFR). This hypothesis predicts that: (1) dunes would not show the west–east decline in diversity evident in inland habitats as the unique selective regime of the dune environment would override the evolutionary diversity patterns evident elsewhere in the CFR; (2) dune diversity would be lower than in adjacent, inland habitats that were not exposed to extreme disturbance regimes during the Pleistocene. We tested this by compiling regional-scale plant species diversity data from dune and interior lowland habitats of the southwestern and southeastern CFR and subjecting the data to species–area analysis. Our results were consistent with the Pleistocene disturbance hypothesis: diversity patterns of dunes did not differ between the southwestern and southeastern subregions, and interior sites were richer in species than dune sites. However, the difference in diversity between interior and dune sites (1.42×) was remarkably marginal. We propose that this is a consequence of the CFR's glacial physiography, where a large expanse of dune habitat was exposed at length along the Palaeo-Agulhas Plain during Pleistocene sea-level lowstands. This vast habitat area would have facilitated the development of a species-rich dune flora.

A fiery past: A comparison of glacial and contemporary fire regimes on the Palaeo-Agulhas Plain, Cape Floristic Region

Landscape-level fire governs vegetation structure and composition in the contemporary Cape Floristic Region (CFR) and was key to the existence of Middle Stone-Age hunter gatherers on the Palaeo-Agulhas Plain (PAP). However, virtually nothing is known about Pleistocene fire regimes of the CFR. We characterized the fire danger climate of the PAP during the Last Glacial Maximum (LGM; 19–26 ka BP) based on palaeo-climate simulations and explored the severity and seasonality of fire danger weather along west-east and coastal-inland gradients across the PAP. We used knowledge of relationships between contemporary fire climate and contemporary CFR fire regimes to propose LGM fire regimes in relation to simulated LGM fire climate. We found that the severity of fire weather during the LGM across the PAP was significantly higher than present; mean fire danger index scores and the incidence of high fire danger days were greater, while the seasonality of fire weather was more pronounced, exhibiting summer-autumn fire regimes across the PAP. Although a more severe fire climate suggests potentially more frequent fires than present, slower fuel accumulation due to colder temperatures, reduced solar radiation and lower atmospheric CO2 may have partly countered this effect. Our proposed LGM fire regimes predict the vegetation of the PAP to have been dominated by fire tolerant, largely Mediterranean-climate formations such as fynbos, renosterveld and grassland, but is unlikely to have provided a driver for mass seasonal east-west migration of large grazers on the PAP.

Large mammals of the Palaeo-Agulhas Plain showed resilience to extreme climate change but vulnerability to modern human impacts

Recent evidence indicates that the now submerged continental shelf, the Palaeo-Agulhas Plain (PAP), formed a novel ecosystem during periods of low sea level. This landscape provided nutrient-rich forage and habitats to a variety of large mammals. This is in contrast to the modern faunal assemblage found in the present-day Cape Floristic Region, which is dominated by landscapes with nutrient-poor soils and unpalatable plants. We used archaeological and paleontological records for the region to reconstruct past large mammal communities. We build on this approach by using modern knowledge of ecosystems and ecosystem processes to help us understand how systems functioned in the past. We reconstruct species communities for the PAP of the last 300 ka and investigate potential gaps in the record using Hutchinson's weight ratio theory. We then compare the results to modern occurrences of mammals on the Cape South and West Coasts and the Serengeti (a comparable migratory system) using general linear models. Both sea-level and sampling effort influenced species richness in both the South and West coast regions during the last seven marine isotope stages. In the South coast we observed a decrease in species richness during intermediate sea levels which indicates patterns of use by early humans and habitat availability. Large mammals showed an extraordinary resilience to extreme habitat loss and survived as refugee species during high sea levels and low habitat availability. However the combination of habitat loss and modern human weapons were the cause of severe extinction rates during the last 400 years.

Post-Late Glacial Maximum Palaeoecological Species Integrity, Phylogeography and Management of Bontebok (Damaliscus pygargus pygargus)

Re-evaluation of bontebok following a multidisciplinary approach indicate its native habitat as the now submerged Palaeo-Agulhas Plain off the southern South African coast, and dominated by C4 grasslands and savannah. Large grazer populations migrated across the plain and around the eastern end of the Cape Folded Belt into the Eastern Cape interior following climate oscillations and geographic-shifts of the winter-/summer-/all-year rainfall isohyets. Presently 77% of all bontebok are found on private farmland with grassland bioregions in the Eastern Cape, Free State and other. Bontebok showed enhanced performance in these grasslands if compared with poor performance on south-western Cape Lowland Renosterveld (SWC-LRV). Renosterveld (RV) was previously perceived as the bontebok's native habitat of origin. We argue that bontebok became trapped in RV due to sea-level rises and consequent multiple species congestion. Bontebok meta-population management on private farms showed significant species improvement when compared with government conservation actions in SWC-LRV. Geographic habitat constraints appear to have been the greatest factor limiting bontebok integrity. IUCN recognizes a global population size of 1,618 as reported by the Non-Detriment Finding of the Scientific Authority of South Africa, whereas actual population size is more than 7,000. We quantify post-1930s bontebok performance against phylogeographic and palaeoclimate proxies.

Seismic stratigraphy of the inner to mid Agulhas bank, South Africa

The inner to mid continental shelf of the Agulhas Bank, which forms part of the Palaeo-Agulhas Plain, is scattered with Pleistocene deposits. Their wide lateral extension is the expression of a flat underlying substrate, availability of accommodation space, and depositional processes in response to glacio-eustatic sea-level change. We present seismic sub-bottom profiles up to 30 m deep, sediment cores up to 5 m in length and Pleistocene deposits that date back to Marine Isotope Stage (MIS) 7 from the inner to mid shelf between the Breede River in the West and Plettenberg Bay in the East. Radiocarbon and optically stimulated luminescence dates are integrated with microfossil analysis into a seismic stratigraphic model comprised of twenty Quaternary facies units within two depositional sequences bounded by shelf-wide unconformities. Sequence Boundary 1 (SB1) corresponds to the erosional unconformity with bedrock and SB2 to the MIS 2 glacial lowstand. Incised palaeo-river channels are associated with both sequence boundaries and cored deposits also mapped seismically from estuarine, lacustrine and fluvial systems are grouped to represent the lower floodplain. The most pervasive stratigraphic pattern in these shelf deposits is made up of the depositional sequence remnant of the Falling Stage Systems Tract (FSST) forced regression from MIS 5e–2. The other dominant stratigraphic group is the Transgressive Systems Tract (TST) associated with the Post-glacial Marine Transgression. The TST makes up an almost equal proportion of deposits in both sequences in the sedimentological record as the FSST, despite the shorter temporal span of the TST. A Wave Ravinement Surface marks the rise in sea level from the Last Glacial Maximum in a landward direction.

Climate and ecology of the palaeo-Agulhas Plain from stable carbon and oxygen isotopes in bovid tooth enamel from Nelson Bay Cave, South Africa

We measured δ13Cenamel and δ18Oenamel in 213 archaeological bovid teeth from Nelson Bay Cave (NBC), spanning the last 22 ka. We also recorded dental mesowear (occlusal relief [high versus low] and cusp shape [sharp, round, or blunt]) of all maxillary first and second molars from NBC. We use these values to explore glacial/interglacial shifts in bovid palaeoecology and to reconstruct aspects of the climate and environment of the Palaeo-Agulhas Plain. Our results indicate that at the time of the Last Glacial Maximum (LGM), there was a significantly greater proportion of C3 (winter-rainfall) grasses, although some C4 (summer rainfall) varieties were present. This conclusion is strengthened by correction for lower pCO2 at the LGM, leading to reduced carbon isotope fractionation in C3 photosynthesis. Terminal Pleistocene and Holocene grazers show a stronger C4 signal. Our findings are consistent with an eastwards extension of winter rainfall at the LGM, as proposed by some previous researchers. Beyond the broad distinction between browsers and grazers, δ13C values reflect species-specific dietary preferences. δ18O is more positive in browsers than grazers, probably due to their deriving a significant proportion of their water intake from evaporatively enriched leaf water. δ18O values do not show significant changes through time. The location of Nelson Bay Cave on the present-day interface between temperate and tropical weather systems means that this area is sensitive to past shifts in the relative importance of these systems. These findings therefore contribute to the reconstruction of past Southern Hemisphere climate dynamics on a glacial/interglacial time scale.

Applying Brantingham's neutral model of stone raw material procurement to the Pinnacle Point Middle Stone Age record, Western Cape, South Africa

The Palaeo-Agulhas Plain (PAP), when exposed, presented Middle Stone Age (MSA) foragers at Pinnacle Point (PP) on the South Coast of South Africa with new sources of raw materials to make stone tools. Sea-level fluctuations and the changing size of the Paleo-Agulhas Plain throughout the Pleistocene PP record ∼165 ka to 50 ka would have altered the availability of different resources, thus potentially forcing new raw material procurement strategies. The relative frequencies of raw material throughout the PP sequence shows that frequencies of raw material types did change, especially after 90 ka. What caused these changing frequencies is debated and centers on whether targeted procurement of specific raw materials was the cause, or if simple raw material availability and abundance due to the changing environmental context in conjunction with opportunistic procurement drove such shifts. The application of a neutral model of stone raw material procurement presented here evaluates whether random walk in the region surrounding the PP site during different coastline configurations (Marine Isotope Stage 6, 5, and 4) explains the observed shifts in raw material usage. Put differently, did opportunistic acquisition of raw materials during random walk in these different environments cause the observed raw material pattern? Model simulations and a sensitivity analysis provide no convincing evidence that observed raw material frequencies at PP resulted from opportunistic acquisition during random walk.

Describing a drowned Pleistocene ecosystem: Last Glacial Maximum vegetation reconstruction of the Palaeo-Agulhas Plain

Pleistocene ecosystems provided the stage for modern human emergence. Terrestrial vegetation communities structure resources for human foragers, providing plant food, wood for fuel and tools, and fibre, as well as habitat for animal prey. The Pleistocene distribution of vegetation communities is seldom considered as a key constraint on hunter-gatherers foraging across the landscape. We used modern vegetation patterns along the Cape south coast to develop a rule-based model of the expected vegetation for a given soil type, precipitation regime and fire regime. We then applied this ruleset to present-day environmental conditions to test and validate the model. We also scaled the climate-vegetation ruleset to account for likely effects of low atmospheric [CO2] and lower temperature in the Last Glacial Maximum (LGM) on plant water use efficiency. The model was then used to postdict vegetation patterns for the LGM using palaeo-landscape reconstruction of geological substrata and soils, and palaeoclimate simulations. This palaeoscape comprised the extensive Palaeo-Agulhas Plain (PAP), which was exposed at lower sea levels during glacial periods. Our model predicts that the PAP was dominated by limestone fynbos in its southern part, and by shale grassland with cappings of dune fynbos-thicket mosaic in the north. Shale and sandstone fynbos were restricted to the western zone, which experienced a stronger winter rainfall regime during the LGM than at present. The entire PAP was dissected by broad and shallow floodplains supporting a mosaic of woodland and grassland on fertile, alluvial soils. This savanna-like vegetation, as well as shale grassland, are poorly represented in the modern landscape, and would have been capable of supporting the diverse megafauna typical of glacial periods. These Pleistocene periods would have presented a very different resource landscape for early modern human hunter-gatherers than the interglacial landscape such as is found in the Cape coastal lowlands today.

Pleistocene vertebrate tracksites on the Cape south coast of South Africa and their potential palaeoecological implications

Body fossil remains usually provide the main palaeontological resource for palaeoecological studies. Ichnology has the capacity to independently complement such data. Fossil tracksites provide a direct record of animals whose tracks have been preserved, and with regard to the Palaeo-Agulhas Plain they have direct relevance in considering palaeoecology. While biases may be present in ichnological data, they are different from the biases inherent in traditional body fossil studies. A ground survey along a 350 km portion of the Cape south coast, between Arniston in the west and Robberg in the east, identified well over a hundred-and-thirty ichnofossil sites in Late Pleistocene coastal aeolianites and lithified foreshore deposits. Some of these tracks were made by extinct species or subspecies. In other cases these tracksites demonstrate spatial range extensions of extant species, when compared with data available from body fossils or historical records. These sites include the largest and best preserved archive of Late Pleistocene hominin tracks thus far described. The tracksites occur on the margin of the Palaeo-Agulhas Plain, which may allow for palaeoenvironmental conclusions to be drawn regarding Late Pleistocene conditions on this extinct landscape. We summarize the most important sites, discuss the limitations and challenges of ichnological studies, and provide perspectives on future work.

The foraging potential of the Holocene Cape south coast of South Africa without the Palaeo-Agulhas Plain

The Palaeo-Agulhas Plain formed an important habitat exploited by Pleistocene hunter-gatherer populations during periods of lower sea level. This productive, grassy habitat would have supported numerous large-bodied ungulates accessible to a population of skilled hunters with the right hunting technology. It also provided a potentially rich location for plant food collection, and along its shores a coastline that moved with the rise and fall of sea levels. The rich archaeological and paleontological records of Pleistocene sites along the modern Cape south coast of South Africa, which would have overlooked the Palaeo-Agulhas Plain during Pleistocene times of lower sea level, provides a paleoarchive of this extinct ecosystem. In this paper, we present a first order illustration of the “palaeoscape modeling” approach advocated by Marean et al. (2015). We use a resourcescape model created from modern studies of habitat productivity without the Palaeo-Agulhas Plain. This is equivalent to predominant Holocene conditions before recent landscape modifications for farming. We then run an agent-based model of the human foraging system to investigate several research questions. Our agent-based approach uses the theoretical framework of optimal foraging theory to model human foraging decisions designed to optimize the net caloric gains within a complex landscape of spatially and temporally variable resources. We find that during the high sea-levels of MIS 5e (+5–6 m asl) and the Holocene, the absence of the Plain left a relatively poor food base supporting a much smaller population relying heavily on edible plant resources from the current Cape flora. Despite high species diversity of plants with edible storage organs, and marine invertebrates, encounter rates with highly profitable resources were low. We demonstrate that without the Palaeo-Agulhas Plain, human populations must have been small and low-density, and exploited plant, mammal, and marine resources with relatively low caloric returns. The exposure and contraction of the Palaeo-Agulhas Plain was likely the single biggest driver of behavioural change during periods of climate change through the Pleistocene and into the transition to the Holocene.