Background

Coprolites have been identified from all geological periods since the Cambrian (e.g., Kimmig and Strotz, 2017) and Ordovician (Hunt et al., 2012). According to Duffin (2012), the first published reports are from the late 17th century, and pioneering studies commenced in the early 19th century (Buckland, 1829, 1835). Subsequently, numerous studies have been performed on coprolites, and their potential has been recognized for, inter alia:

1. identifying either the producer of the coprolite or (in the case of a carnivore) the identity of its prey;

2. enabling palaeoenvironmental and palaeoecological reconstructions through, for example, palynological and phytolith studies, and isotopic studies on ingested skeletal material or undigested plant matter; and,

3. through the identification of soft tissue fossil inclusions (in coprolites of carnivorous vertebrates), deriving information on host-parasite relations and trophic food webs (Qvarnström, Niedźwiedzki, and Žigaitė, 2016).

The archaeological and traditional body fossil records from the Cape south coast of South Africa have provided an extensive inventory of palaeoecological and palaeoenvironmental evidence, with implications for the wider palaeoanthropological record. Some of this evidence comes from carnivore and scavenger dens. Not surprisingly, these have yielded a number of coprolites, in particular, those of hyaenas such as the brown hyaena (Hyaena brunnea) (Rector and Reed, 2010). Coprolites in hyaena dens and genet latrines were noted at Klasies River, ∼100 km east of the eastern limit of our study area (Deacon and Deacon, 1999). Van Pletzen (2000) also documented the presence of coprolites at Klasies River, noting that carnivores had probably scavenged remains left by humans. Within our study area, hyaena coprolites have been reported from the ∼100 ka layers at Blombos Cave (Badenhorst, Van Niekerk, and Henshilwood, 2016) and from PP 30 (a carnivore den site near Pinnacle Point), where they were found not to contain pollen (Curtis Marean, pers comm, 26 December 2019; Louis Scott, pers comm, 3 January 2020).

Carrión et al. (2000) reported an open-air hyaena coprolite site near Oyster Bay (∼120 km east of the eastern limit of our study area), which was eroding out of a palaeosol dated to ∼70 ka. The associated pollen assemblage differed markedly from the modern vegetation, implying displacement of vegetation zones to lower altitudes and overall cooler conditions (Carrión et al., 2000). It was also noted that not all coprolites examined in southern Africa have yielded pollen; many have been reported to be “sterile.” Scott et al. (2003) provided a table of 10 South African sites where palynological analysis of hyaena coprolites had been attempted, suggesting that pollen was less likely to be found in older coprolites or in those that had been subjected to repeated moisture fluctuations.

On the Cape west coast, Pliocene hyaena coprolites have been identified at Langebaanweg (Graham Avery, pers comm, 4 January 2020), and Pleistocene hyaena coprolites have been reported from Duinefontein 2 (Cruz-Uribe et al., 2008; Klein et al., 1999), Elandsfontein (Klein et al., 2007), Sea Harvest (Grine and Klein, 1993), Spreeuwalle (Graham Avery, pers comm, 4 January 2020), Swartklip (Hendey and Hendey, 1968; Klein, 1975), and Ysterfontein (Avery et al., 2008). Some of these were in open, sandy aeolian contexts, probably close to water bodies (Graham Avery, pers comm, 4 January 2020). Additionally, Singer and Wymer (1968) reported that at Elandsfontein, Van Zinderen-Bakker and Coetzee had extracted pollen grains from coprolites that suggested a savanna-woodland palaeoenvironment (rather than fynbos). Klein et al. (2007) reported that these results and the mammalian fauna indicated proximity to water. Parkington (2018) reported coprolites in a hyaena den dated to ∼280 ka at Hoedjiespunt, near Saldanha Bay.

Elsewhere in South Africa, there are reports of coprolite analysis at or close to hominin sites from the Sterkfontein Valley, northwest of Johannesburg. In one instance, a possible human hair was described from a hyaena coprolite dated to 257–195 ka from Gladysvale Cave (Backwell et al., 2009). Pollen analysis has also been performed on coprolites from Malapa, dated to 1.97–1.75 Ma (Bamford et al., 2010). Gil-Romera et al. (2014) compared the inner and outer portions of hyaena coprolites from Equus Cave, near Taung in Northwest Province, and concluded that the inner portions might be of superior palynological value.

To the best of our knowledge, coprolites embedded in aeolianites have not previously been described from southern Africa, and few coprolites of Pleistocene herbivores have been identified. It could be argued that the different composition of scat material compared with the sandy substrate might make preservation unlikely, and that reworking and destruction might occur even if scats were quickly buried. However, the capacity of Pleistocene palaeosurfaces on the Cape south coast to provide a record of events that transpired upon them, when they were composed of unconsolidated sand, has repeatedly proved surprising. Viewed in this context, the identification of the six open-air ichnosites described here is perhaps not unexpected. Such sites hold the potential for palaeoenvironmental interpretation in an area of great importance for the emergence of modern humans (e.g., Marean, 2010; Marean et al., 2014).

Jouy-Avantin et al. (2003) provided a standardized method for the description of coprolites, but they approached this effort from an archaeological perspective, restricting the use of the term “coprolite” to material found in archaeological sites. Although the six ichnosites described here date to a time when hominins inhabited the region, there is no evidence that they can be regarded as archaeological sites. Nonetheless, the standardized method suggested by Jouy-Avantin et al. (2003) can be extrapolated to the description of all coprolites and hence is of relevance here.

Geological Setting

Within our study area, the basement geology consists of Palaeozoic quartzite and shale exposures of the Cape Super-group, and Precambrian exposures of the Cape Granite Suite (Newton, Shone, and Booth, 2006). The structural architecture of the coast is shaped by the relative distribution of these deposits, with sandy embayments separated by competent headlands. Coastal sediments are composed of modern sandy beaches and unconsolidated Holocene dunes that generally fill the embayments and are distributed across the adjacent continental shelf.

Geologically, four of the ichnosites described here occur in the Waenhuiskrans Formation (Malan, 1989), and two occur in the Klein Brak Formation (Malan, 1991). These two formations form Pleistocene elements of the Cenozoic Bredasdorp Group, which crops out along much of the southern Cape coastline. These sediments are amenable to dating using optically stimulated luminescence (OSL) techniques (e.g., Bateman et al., 2011; Carr et al., 2010, 2019; Roberts et al., 2008, 2012).

The Waenhuiskrans Formation consists of aeolianites that are often cross-bedded, with bedding planes that are frequently orientated close to the angle of repose of windblown dunes. The oldest Waenhuiskrans Formation sediments dated thus far are from Marine Isotope Stage (MIS) 11 (Roberts et al., 2012), while the youngest are from MIS 3 (Carr et al., 2019). The Klein Brak Formation consists of a variety of marine and foreshore deposits, including shoreface and lagoonal sedimentary facies, and washover fans. The oldest Klein Brak Formation deposits dated thus far are also from MIS 11 (Roberts et al., 2012), and the youngest are from MIS 5 (e.g., Bateman et al., 2011; Carr et al., 2010; Cawthra et al., 2018; Roberts et al., 2008).

Erosion of Pleistocene sediments due to wave, wind, and other erosive agents is often rapid, and anthropogenic degradation (e.g., graffiti) is also common. Cliff collapse events may result in brief exposure of track-bearing surfaces on rock slabs before they slump into the ocean, or before their quality deteriorates through weathering. Substantial movements of sand by wave action and tidal currents contribute to a dynamic littoral landscape, where sand deposits several metres thick can be removed within days, briefly exposing seldom-seen underlying deposits.

In the portion of our study area west of Still Bay, aeolianites are well cemented, with little potential for exfoliation of layers and exposure of track- or coprolite-bearing surfaces. In contrast, aeolianite outcrops east of Still Bay are generally less well cemented, and suitable track-bearing surfaces are encountered more frequently. Sedimentary structures can also be examined in cross-section, where tracks, if present, take the form of soft-sediment deformation structures (Owen, Moretti, and Alfaro, 2011).

Because coprolites embedded in these Pleistocene sediments have not been previously reported, there has been no prior discussion on taphonomy or their fate after re-exposure. However, the prevalence of tracksites has been postulated by Roberts and Cole (2003) to arise from a combination of factors: a cohesive moulding agent provided by moist sand; rapid track burial associated with high sedimentation rates; rapid lithification via partial solution and reprecipitation of bioclasts; and re-exposure of track-bearing surfaces through shoreline erosion. The initial process may have been enhanced through microbial activity increasing the binding properties of the substrate (Seilacher, 2008). Many of these factors may be inferred to operate in the preservation of coprolites.

Site A

Eight large elephant tracks with substantial displacement rims were identified east of Still Bay in 2019 on the surface of a large block (∼2 m long and ∼1 m wide). It had fallen down from the cliffs above, which comprised aeolianites of the Waenhuiskrans Formation (Figure 2). Aeolianites within a few kilometres of this locality were previously dated to between 140 ± 8 ka and 91 ± 5 ka (Roberts et al., 2008). Some tracks appeared to be composite, consistent with elephant manus-pes pairs; two of the larger resulting depressions measured 69 cm and 53 cm in length and ∼30 cm in width. Two of these depressions contained loose, smaller rocks with unusual shapes, embedded in semiconsolidated sand that partially filled the tracks.

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The portions of these smaller rocks that were exposed to the air, as well as multiple raised areas on the track-bearing surface, were very dark blue in color, reminiscent of a biofilm layer as described from a site few kilometres away (Helm et al., 2017). The underlying rock beside the tracks was a lighter blue-grey in colour. One of the very dark raised protuberances (a putative coprolite) was detached from the surface with ease. Preservation quality was poor. The largest putative coprolite measured ∼15 cm in maximum length, ∼10 cm in maximum width, and ∼3 cm in maximum depth. A sample for OSL dating (Leic20030) was taken from the edge of the surface, in an area devoid of tracks and probable coprolites.

Site B

Site B was located on the coast between the communities of Hartenbos and Little Brak River (Figure 3a). An ∼1 m² surface contained more than 30 raised features, which had a lighter grey-brown colour than that of the surrounding surface. Some of these were eroded and had a “hollowed out” appearance (similar to those at site E and site F, described below), whereas others appeared to be flattened. Preservation quality was poor. These features, up to 5 cm in length, 3 cm in width, and 2 cm in depth, were identified at the landward end of a large palaeobeach exposure of the Klein Brak Formation, which is usually covered in current-borne sand. It contains many rimmed potholes for which elephant tracks have been inferred as precursors (Helm et al., 2021). The closest of these potholes occurred several metres from the raised features (Figure 3b). A small-carnivoran trackway was identified on the same surface, a distance away from the raised features. A sample for OSL dating (Leic20029) was obtained from the edge of the surface, within a few metres of the raised features.

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Site C

Site C lies in the Garden Route National Park and comprises three sites in close proximity. Tracks and swim traces of large reptiles, consistent with Nile crocodile (Crocodylus niloticus) and water monitor (Varanus niloticus), were identified in 2018 along this coastline, and brief mention was made of possible whitish coprolites (Helm et al., 2020a). These were found on the same bedding plane surface as the tracks, either on the same loose blocks or on adjacent loose slabs (Figure 4a). They were typically rounded or cylindrical, as much as 8 cm in length, 3 cm in width, and 2.5 cm in depth. The Klein Brak Formation surface was interpreted as representing a lagoon or near-lagoon environment (Helm et al., 2020a). Caution was exercised in interpreting these features as possible coprolites, because rhizoliths on the same surfaces also had a white colour and an elongated form.

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In 2019, the rock surface in question could not be located, as the area was covered with sand. However, a possible coprolite, raised above the surface, whitish in colour and eroded and hollowed in places, 15 cm long × 5 cm wide (Figure 4b), was identified and sampled from a newly exposed fallen slab containing crocodile tracks and swim traces (Helm and Lockley, 2021). A subaqueous environment was required to register such swim traces. A sample was taken for OSL dating (Leic21028) from a nearby rock with similar lithology, also containing crocodylian traces. Previous OSL ages from aeoliniates sampled in the vicinity of this site ranged from 148 ± 10 ka to 112 ± 6 ka (Bateman et al., 2011, site 9e). Photogrammetry studies were applied to this surface (Figure 4c).

A nearby large exposed surface on a fallen block from the same horizon contained tracks of C. niloticus, V. niloticus, mammals and birds, and Middle Stone Age lithics (Helm et al., 2020a). A probable coprolite with similar morphology to those described at site E was noted within one of the mammal tracks, and it was sampled (Figure 4d). Track morphology suggested a possible brown hyaena trackmaker.

Site D

At an in situ coastal site in Goukamma Nature Reserve, 130 nodular features were identified in 2019 on an aeolianite surface of the Waenhuiskrans Formation (Figure 5). Maximum dimensions of the rippled surface, which is often covered by sand, were 127 cm × 35 cm. A strike of 320° and dip of 12° were recorded, indicating that the predominant depositional wind direction was from the southwest. Most of the nodular features were approximately round or oval in shape, typically 2–3 cm in maximum length, and flattened, but some were joined together or exhibited irregularities. They were blackish and much darker than the underlying greenish-brown aeolianite surface, and they appeared more or less evenly spread in a sinuous shape along a trackway consisting of four medium-sized bovid tracks that was orientated in a northwesterly direction. Preservation quality was good. The tracks were 7.5–8 cm in length, with a pace length of ∼47 cm. The shallow depressions formed by three of the tracks contained some of the nodules. Four of these nodular features were removed for further analysis, evenly spaced through the sequence. A sample for OSL dating (Leic21013) was obtained from a surface situated 2.5 m higher in the stratigraphic section, as reported in Helm et al. (2022a).

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Site E

Site E (Figure 6), in Goukamma Nature Reserve, ∼30 m east of site D, was identified in 2019. The main surface, 4 m higher in the stratigraphic section than site D, contained features that resemble coprolites preserved on an inclined aeolianite layer of the Waenhuiskrans Formation. It exhibited a strike of 330°, a dip of less than 30°, and maximum dimensions of 6.6 m × 1.5 m. This surface is often covered by sand. At other times, when it is exposed, it is buffeted by waves at high tide. It contained about 30 features, which appeared “plastered” onto the underlying surface. These were fairly evenly spaced. The largest measured 11 cm × 7 cm. “Sausage shapes” were frequently present, typically ∼5 cm × 1 cm in size, and frequently partially hollow. Many of the features appeared slightly flattened. The features appeared light grey in colour, in subtle contrast to the underlying surface, which exhibited a slightly more grey-brown colour. As a result of the apparent flattening and the hollow nature of many of the features, preservation was of medium quality. In addition, about 50 small, unidentifiable tracks, approximately 4 cm in length and width, were present on the same surface.

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Another surface exposure lay 42 cm above the main surface. Measuring 80 cm×60 cm, it contained more than 10 tracks and 10 features resembling coprolites, similar to those on the main surface, as well as a single, larger equid track. Remarkably, in the more than 2 m of stratigraphic sequence immediately overlying these surfaces, there were a further six layers in which similar features resembling coprolites were evident, in addition to deep elephant tracks seen in profile (Helm et al., 2018b, figure 3C), and smaller unidentifiable tracks, also seen in profile. Although other causes of soft-sediment deformation structures needed to be considered (Owen, Moretti, and Alfaro, 2011), the proboscidean origin of the large tracks was confirmed where one of these layers was well exposed on a surface 3 m to the east, on which elephant tracks of similar size were preserved in epirelief.

Over a 2.6 m stratigraphic section, eight layers thus appeared to contain coprolites (Figure 7). In all cases, they appeared similar in size and form to those noted on the main surface and were often partially hollow. This was a particularly track-rich area, with tracks of the extinct long-horned buffalo (Syncerus antiquus) close by, as well as many more manifestations of elephant tracks (which were noted in profile in seven layers over a stratigraphic sectional height of 10 m). With relative ease, samples for analysis were detached from the main layer, the layer 42 cm above it, and the top layer (where they could be loosened by hand). A sample for OSL dating (Leic21013) was taken at a level 1.5 m in stratigraphic section below the main layer, as reported in Helm et al. (2022a).

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Site F

Site F was identified in 2020 in the Goukamma Nature Reserve, ∼4 km east of site E. Compared with site E, there was extensive hollowing of most of the eight features, which were found on a single, smaller bedding plane surface. They had a more spherical, less sausage-shaped form (Figure 8), with diameters ranging 1–3 cm. The features exhibited a lighter-grey colour than that of the underlying surface. Due to the hollow nature of most of the features, the preservation was at best of medium quality. The underlying palaeosurface was eroded and irregular, making it impossible to determine if it contained tracks.

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Samples have not been obtained from site F. However, a sample for OSL dating was obtained from a rock outcrop 2.5 km to the west. Another OSL date of 91 ± 5 ka was previously reported from an area close to this locality (Bateman et al., 2011, site 7b).

Petrography

Transmitted-light microscopy revealed that organic matter was preserved in all samples, but that it was more pronounced at sites B, C, and E (also panels B, C, and E in Figure 9). The coprolites may mostly be represented by casts, but a veneer of organic matter exists, commonly infilling voids between the clasts. The dominant constituent of all samples analysed was quartz, with minor glauconite, lithic fragments, and calcite cement.

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Palynology

The samples were devoid of palynomorphs, and only amorphous organic matter and fragments of silica were present. An exception to this was the presence of a large quantity of Pinus pollen within the samples from site E. Pinus is a neophyte (introduced to the area in the 1800s), and therefore the presence of these pollen grains indicates modern contamination, likely as a result of the hollow nature of the coprolites.

Phytolith Analysis

Only numerous silica chips and fragments of sand were found. No opaline silica indicating the presence of phytoliths was identified.

OSL Dating

As has been detailed previously, the quartz obtained from these sites is characterised by a bright, fast component–dominated signal, with few aliquots rejected when following standard quartz single aliquot regeneration protocol internal checks (recuperation, recycling ratio, etc.; see Supplementary Information). The resulting equivalent dose (D_e) distributions were also typical of aeolian deposits from this region and showed limited interaliquot scatter, suggesting that the weighted mean D_e in each case was most likely representative of the burial dose of interest. The OSL age obtained for site A is consistent with the results presented in Roberts et al. (2008). Site C was sampled for OSL dating, but on inspection, it proved to be a far from ideal sample due to the thin nature of the track-bearing truncation surface, which overlay heavily bioturbated deposits, and the presence of small cavities throughout the material, which clearly presented a risk of light penetration prior to and during sampling. Analysis of this sample was therefore not progressed. For sites D and E, Leic21013 was obtained from within the stratigraphic section between the levels of the two sites, and it was previously published in relation to nearby pinniped traces (Helm et al., 2022a). Site F was not directly sampled, but sample Leic20025 was obtained from an outcrop 2.5 km to the west. Table 1 provides a summary of the findings.

Site A

Site A represents an elephant tracksite and possible elephant coprolite site. The OSL date of 139 ± 10 ka is consistent with previous results from the Still Bay area (Roberts et al., 2008) and places it within MIS 6 or MIS 5e. The African elephant, Loxodonta africana, is the only plausible trackmaker. It appears that coprolites have not previously been described from this species. The ease with which the sample could be removed from the surface supports the contention that it is a possible coprolite.

Elephant droppings are large, sometimes exceeding 20 cm in length, and may be barrel-shaped; 100 kg of dung may be produced per day (Stuart and Stuart, 2019). A bolus of dung has a cylindrical form, slightly elliptical at each end (Morrison et al., 2005). Dung is coarse and contains fibrous material, such as twigs, bark, leaves, and fruit (Van den Heever, Mhlongo, and Benadie, 2017). Depending on the season, African elephants defecate 12 to 38 times per day (Olivier, 2010). Decay rates are affected by variables such as climate, slope, and bolus size (Barnes et al., 2006; Olivier, 2010).

Given the prevalence of documented Pleistocene elephant tracksites on the Cape south coast (Helm et al., 2021, 2022b) and the prodigious amounts of dung produced, the possibility of encountering elephant coprolites is considerable, assuming that they are suitably preserved and recognizable. Relatively rapid burial would be a prerequisite to allow for the presence of the well-preserved tracks that are evident at site A.

Site B

Site B contains raised, hollow features similar to those noted at site E and site F, as well as a number of flattened features, all on a documented track-bearing surface. Although elephant tracks occur a few metres away, the coprolite features do not resemble elephant dung unless they represent extensively eroded vestigial examples. The features are interpreted as probable coprolites, at the landward end of a palaeobeach exposure. The OSL age of 108 ± 7 ka suggests that site B represents the approximate end of the MIS 5e sea-level highstand and early regression into MIS 5d.

Site C

Site C may contain coprolites of reptiles and mammals from three adjacent locations, but this is not certain. One location (Figure 4a) could not be reidentified, where the features are rather angular in shape, and it could also represent a localized breccia, a phenomenon that has been reported from Pleistocene sediments on the Cape south coast (Hodge, 2013).

The surface of one of the other locations (Figure 4b,c), which contained swim traces of the Nile crocodile (Crocodylus niloticus), would have originated as a submerged area within a shallow lagoonal environment (Helm and Lockley, 2021). Previously, Van den Heever, Mhlongo, and Benadie (2017) noted that crocodiles defecate both on land and in water, and that the initially green droppings turn white in time (droppings are reported as being 5–12 cm in length and 3–5 cm in width). The raised, slightly eroded feature exhibited dimensions and a light colour that suggested a possible crocodile coprolite. Stuart and Stuart (2019) noted that “crocodile droppings are normally soft. . . they are seldom found, because they are quickly covered by sand or mud.” This appears to be the first report of a possible C. niloticus coprolite. The site shown in Figure 4d can be interpreted as a probable coprolite occurring in a possible brown hyaena track.

Unfortunately, the samples obtained from site C for OSL dating proved problematic. However, the most likely age of the site C palaeosurface is MIS 5e, close to the sea-level highstand of 126 ka (Helm et al., 2020a; Helm and Lockley, 2021), given the need of ectothermic groups such as crocodiles for warm temperatures. Sea levels would have been as much as 6–8 m higher than at present (Carr et al., 2010), with a warm climate that was able to support large reptiles. This age estimate is consistent with the previously obtained range for the vicinity of ∼148–92 ka (Bateman et al., 2011).

Site D

Site D comprises ∼130 nodular features, interpreted with confidence as coprolites, in and beside a trackway of a medium-sized bovid on an aeolianite palaeosurface. This phenomenon appears to be unprecedented in the southern African ichnology record, although the global record of coprolites attributed to large herbivores extends as far back as the Triassic (Fiorelli et al., 2013). The track morphology does not permit identification to genus or species level, but the number of coprolites within a relatively small area suggests possible territorial behaviour (Alex Van den Heever, pers comm, 2019). The bontebok (Damaliscus pygargus pygargus) is a plausible candidate. Stuart and Stuart (2019) noted how territorial rams of this species leave separate but concentrated heaps of droppings, with an average pellet length of 1.5 cm. The OSL age of 76 ± 5 ka (Helm et al., 2022a) places this site within MIS 5a, before the migration of the coastline onto the continental shelf during MIS 4.

Are there other plausible explanations for the features that are present at site D, particularly as a result of the intriguing colour difference between the nodules and the underlying aeolianite substrate? Adhesion structures, such as adhesion warts, could be considered (Kocurek and Fielder, 1982). However, the lack of any demonstrable relation between the 130 nodular structures and the prevailing wind direction argues against such a notion. Nodular pisolite concretions or carbonate or manganese/ferric nodules of diagenetic origin (e.g., Johnson, 1989) could be postulated. However, advancing either of these suggestions would require an explanation of why they have not been noted anywhere else in the entire study area, and acknowledgement that: (1) their only documented occurrence happens to occur along a trackway of a medium-sized bovid, and (2) the nodular features are consistent in number, size, and pattern with the scat of such a trackmaker.

The quality of track preservation in aeolianites and cemented foreshore deposits on the Cape south coast is often inferior to tracks preserved in finer-grained sediments. Belvedere and Farlow (2016) developed a four-point scale for the evaluation of track preservation, whereby “0” represents a virtually unidentifiable track, and “3” represents a track of exceptional quality. Unfortunately, Pleistocene Cape south coast tracks seldom rise above “2” on this scale. It is therefore not surprising that the trackmaker at site D cannot be identified to species level, although there are sufficient morphological features (e.g., interdigital sulcus) to indicate a bovid trackmaker and the direction of travel.

Site E

The evidence at site E strongly suggests that it represents the latrine of a small carnivoran. Unfortunately, the tracks, which were made on a dune surface, are not identifiable to family level, but their size (∼4 cm) provides an indication of potential trackmaker candidates. The arrangement of what are interpreted as coprolites and the minimum size of the latrine (which is at least the size of the main surface) can provide further pointers. A remarkable feature of this site is the occurrence of similar coprolite features in eight layers through a stratigraphic section of 2.6 m, in which structures characteristic of concentrated elephant activity also occur. It is not possible to determine the amount of time that elapsed for these successive dune foresets to have formed. However, regardless of this uncertainty, persistence in use of a latrine site over time (despite an elephant presence) can be inferred. As with nearby site D, the OSL age of 76 ± 5 ka (Helm et al., 2022a) places this site within MIS 5a, before the migration of the coastline onto the continental shelf during MIS 4.

Plausible alternative explanations for the features at site E need to be considered. The hollow, sausage-shaped morphology that is sometimes evident might prompt suggestions that these are invertebrate burrow features, or possibly rhizoliths. Invertebrate burrows are very common on aeolianite and cemented foreshore deposit surfaces in the study area. They are usually epifaunal, less commonly infaunal, and certainly not “suprafaunal,” a term that would need to be invoked to advance such a hypothesis. They usually have a characteristic burrow appearance, and they are typically not raised more than a few millimetres above the palaeosurface. In no cases have raised features like this been observed other than at site B, site E, and site F. Likewise, rhizoliths (Durand et al., 2018), which have a characteristic structure that is often associated with changes in the surrounding substrate, have never been noted as raised features in clusters of the kind seen at site B, site E, and site F. Furthermore, the question can be asked: Why do the only surfaces on which such features have been observed also contain a large number of fossil tracks of a size that is consistent with the tracks of small carnivorans that create latrines? (The underlying surface at site F is too eroded to determine whether or not tracks are present.) As discussed above, the inability to identify the trackmaker to genus or species level is not unusual for Pleistocene tracksites in the study area.

Many species of terrestrial carnivorans use latrines (sites where scat is repeatedly deposited) as a method of olfactory communication (Hulsman et al., 2010). Avery and Fosse (2012) documented a brown hyaena (Hyaena brunnea) den and latrine site on the Skeleton Coast of Namibia. It had been periodically used for at least 16 years, and it was estimated that one accumulation layer had taken 2 years to develop. Hulsman et al. (2010), in investigating patterns of scat deposition by H. brunnea in the Waterberg of northern South Africa, observed low defecation rates at latrine sites, with a median value of less than 1 defecation in 30 days.

Site F

Site F has not yet been sampled, although the previously reported date of 91 ± 5 ka from a nearby site (Bateman et al., 2011, site 7b) incorporates a range from MIS 5c to MIS 5b, and the result of 78 ± 5 ka (Leic20025) from a site 2.5 km to the west suggests deposition during MIS 5a. The hollow nature of many of the possible coprolites might adversely impact the results of further study. The absence of vertebrate tracks is not surprising, given the small size and irregular, eroded appearance of the palaeosurface exposure.

Complementary Records

The ichnology record complements the body fossil record along the Cape south coast. For example, the presence of giraffe, hatchling turtles, crocodiles, and large birds is only known through their tracks (Helm et al., 2018a, 2020a, 2020c; Lockley et al., 2019). Nonetheless, the body fossil record (e.g., Klein, 1976, 1983; Marean et al., 2000, 2014; Rector and Reed, 2010) provides a useful census with which to consider the producers of the coprolites at site D (possible bontebok) and site E. In the case of site E, consideration of the carnivorans of appropriate size to create sizeable latrines provides another avenue of evidence. For example, the relatively scattered nature of the latrine droppings (Stuart and Stuart, 2019; Van den Heever, Mhlongo, and Benadie, 2017), combined with the size and shape of the described features, suggests that they may have been produced by a mongoose (family Herpestidae) or genet (family Viverridae).

There may be considerable variation in the contents of droppings from members of these families. For example, Stuart and Stuart (2019) and Van den Heever, Mhlongo, and Benadie (2017) noted that the water mongoose (Atilax paludinosus) deposits droppings near water, and that they contain crab fragments, insect remains, hair, and small bones. While the track-rich nature of the surrounding sediments (and evidence of repeated use over time) might suggest proximity to a source of water, the list of candidates remains long.

The body fossil record and the ichnology record further complement each other once their different biases are considered. The primary accumulators of body fossil assemblages (humans, jackals, hyaenas, leopards, porcupines, owls) have predation and transport biases; these biases limit the representativeness of such assemblages. In contrast, the trace fossil record provides a census of the animals that left a record on dune and beach surfaces. However, a different bias exists, as larger, heavier animals tend to leave larger, deeper tracks, and usually larger scat, which are more likely to be recognized upon re-exposure as coprolites.

Shared Tendencies

The flattened forms of some coprolites and the hollow nature of others were observed. Diagenesis and taphonomy need to be considered in the interpretation of these features. For example, flattening might result from pressure from overlying sand layers when the scat was still malleable, a concept which has been addressed by Niedźwiedzki et al. (2016). Hollow coprolites might be explained through the exterior portions of the scat being cemented after burial by sand, whereas the interior sections decomposed. Cavities in the interiors of coprolites have also been attributed to the release of decay gases (e.g., Harrell and Schwimmer, 2010). Alternatively, scatophagic invertebrates may hollow out portions of the scat soon after deposition (Jouy-Avantin et al., 2003). Such activities by termites have been noted in neoichnological observations (Alex Van den Heever, pers comm, 2019).

In summary, there appear to be tendencies that Cape south coast coprolites share:

1. They occur within, or adjacent to, vertebrate tracks. This can be contrasted with the phenomenon described by Telles Antunes, Balbino, and Ginsburg (2006), in which vertebrate tracks were found on the surfaces of trampled coprolites.

2. They can be detached with relative ease from the underlying surface (this is highly unusual, as protruding areas typically represent the most erosion-resistant portions of surfaces and require substantial effort to remove).

3. They exhibit a “plastered on” appearance.

4. They may have a different colour and consistency compared with the underlying surface.

5. They may appear flattened or hollow.

Prospects and Potential

Many of the vertebrate tracksites take the form of transmitted tracks (undertracks). For example, if elephant tracks create a 30 cm disturbance in underlying layers (as observed in profile), and if bedding planes are 2 cm apart, then there will be 15 opportunities to observe tracks, if each of these individual bedding planes becomes a surface exposure. In contrast, coprolites will typically only be evident on the layer on which the scat was deposited. Combined with the fact that tracks are a more common occurrence than scat, coprolite sites can be expected to be a relative rarity.

Nonetheless, a dedicated search may yield more sites. Awareness of the examples identified thus far can be a spur to further discoveries, as ichnologists exploring the coastline train themselves to look at unexpected raised features with the possibility of coprolites in mind. “Citizen scientists” can play a similar role.

Disappointingly, given the negative palynology and phytolith results, the potential of Cape south coast coprolites to deliver more detailed palaeoenvironmental information is yet to be realised. The observations of Scott et al. (2003) are prescient: Many coprolites are “sterile,” and repeated moisture fluctuations might decrease the likelihood of palynology studies yielding positive results. The possibility needs to be entertained that conditions are not favourable for the preservation of the required microscopic features in coprolites embedded in these regional Pleistocene palaeosurfaces. If so, the remarkable array of macroscopic features identified thus far can still be interpreted and appreciated. However, it is too early to reach such a conclusion, as new sites may yield more positive results. It is noteworthy that the petrographic analyses did confirm the preservation of organic matter (if not pollen) that may be amenable to isotopic analysis.

Future work can therefore include the following steps:

1. identify further sites;

2. sample all sites according to standard protocols;

3. submit samples for OSL dating, petrography, palynology, and phytolith analyses;

4. add carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope studies to the above analyses; and

5. perform geochemical testing to identify phosphate levels in coprolites attributed to carnivorans, compared with levels in the surrounding aeolianites.

The sites identified and dated thus far are from MIS 6 or 5e through MIS 5a. Searching for evidence of coprolites in MIS 11 deposits at Dana Bay and in MIS 3 deposits at Robberg would provide another line of investigation, as preservation conditions might have been different at those times.