Pleistocene large reptile tracks and probable swim traces on South Africa’s Cape south coast

Abstract

<jats:p> The Cape south coast of South Africa contains a wealth of Pleistocene vertebrate trace fossil sites in aeolianites and cemented foreshore deposits. Published studies have described mammal and avian tracksites identified along this coastline. We report here on a number of Pleistocene palaeosurfaces within the Garden Route National Park that exhibit tracks of large reptiles, including probable swim traces. The tracks were probably made by more than one species, and may include a crocodylian. There are no extant reptiles in this coastal region capable of making such tracks and traces, which probably represent an indication of a previously more extensive range for the Nile crocodile and a monitor lizard. These findings demonstrate the potential for ichnology to complement the traditional body fossil record. Two Middle Stone Age stone artifacts were found embedded in one palaeosurface containing multiple reptile trackways. These discoveries have implications for the understanding of Pleistocene palaeoenvironment and palaeoclimate – in an area which is important in the study of modern human origins. </jats:p>

Pleistocene golden mole and sand-swimming trace fossils from the Cape coast of South Africa

“…A possible explanation involves considering a temperature-related analogy with other species that are known from their Pleistocene tracks, but which no longer occur in the region. For example, the southward cooling of habitat currently forms the most significant range-limit determinant for the Nile crocodile ( Crocodylus niloticus ), due to its ectothermic biology (Helm et al, 2020b). Likewise, for sea turtles ( Chelonioidea ), the presence of successful breeding (which has been documented through discovery of hatchling trackways) implies a range of sand temperatures of 25–35 o C (Lockley et al, 2019).…”

“…To date, the large numbers of tracksites reported from the Pleistocene of the Cape south coast have revealed an impressive diversity of tetrapods, most of which represent mammals that are easy to identify from trackways at the family level and sometimes the genus level (Helm et al, 2020a). A few reptile trackways have been documented (Helm et al, 2020b), among which the sea turtle trackways appear to be attributable to known genera ( Dermochelys, Caretta ), even species (Lockley et al, 2019). Avian tracks show a diversity of size and morphology, but are not easily attributed to trackmakers at the genus level.…”

“…More than 250 such sites have been identified in aeolianite and cemented foreshore deposits, indicating a diverse trace fossil record with the potential to complement and greatly enhance the rich traditional body fossil archive in the region (e.g., Klein, 1976Klein, , 1983Klein et al, 2007;Rector and Reed, 2010;Marean et al, 2014;Matthews et al, 2019), which is derived largely from archaeological sites and scavenger dens. Examples of these ichnological findings include reports of hatchling turtle tracks (Lockley et al, 2019), crocodile and water monitor tracks (Helm et al, 2020b), giraffe tracks (Helm et al, 2018a), and hominin tracks (Helm 2018b(Helm , 2019a. These discoveries have significant palaeo-environmental implications, for example, giraffes require a savanna ecosystem, and crocodiles and turtles require warm temperatures and sufficient water in which to breed successfully.…”

Large mammal tracks in 1.8-million-year-old volcanic ash (Tuff IF, Bed I) at Olduvai Gorge, Tanzania

“…Additional late Pleistocene human track sites from the region include Nahoon (~124 ka) in Eastern Cape Province, and Brenton-on-Sea (~90 ka) and Langbaan Lagoon (~117 ka), both in Western Cape Province (Berger & Hilton-Barber, 2000;Jacobs & Roberts, 2009;Roberts, 2008;Roberts & Berger, 1997). Numerous fossil animal tracks and trackway sites preserved in aeolianites (i.e., from Witsand to Robberg Nature Reserve) that represent contemporary animal genera were also discovered along the Cape south coast (Helm, Cawthra, Combrink, et al, 2020;Helm, Cawthra, Cowling, et al, 2020;Helm, Cawthra, de Vynck, et al, 2019;Helm, Cawthra, Hattingh, et al, 2019;Helm et al, 2017;Roberts, 2008 (Altamura et al, 2018); 3 -Koobi Fora (~1.5 Ma), Ileret (~1.52 Ma), and GaJi10 sites (~1.43 Ma) (okote Member, Koobi Fora Formation), Lake Turkana, Kenya (Behrensmeyer & Laporte, 1981;Bennett et al, 2009;2014;Brown et al, 2006;hatala et al, 2017;Roach et al, 2016); 4 -sandai Plain (Loboi silts), Lake Bogoria, Kenya (Late Pleistocene) (scott et al, 2008); 5 -Engare sero, Lake natron, Tanzania (5760 ± 30 to 19.1 ± 3.1 ka) (Balashova et al, 2016;hatala et al, 2020;Liutkus-Pierce et al, 2016;Zimmer et al, 2018); 6 -Laetoli, Tanzania (~3.6 Ma) (Day & Wickens, 1980;Leakey, 1978b;Raichlen et al, 2010); 7 -nahoon site, Eastern cape Province, south Africa (~124 ka) (Jacobs & Roberts, 2009;Roberts, 2008); 8 -Brenton-on-sea, Western cape Province, south Africa (~90 ka) ; 9 -still Bay, Western cape Province, south Africa (~90 ka) (helm, cawthra, de Vynck, et al, 2019;Roberts et al, 2008); 10 -Langbaan Lagoon, Western cape Province, south Africa (~117 ka)…”

Newly identified hominin trackways from the Cape south coast of South Africa

“…Indeed, our Cape south coast ichnology project has documented more than 250 vertebrate tracksites in our study area (Figure 1), which extends for 350 km from the town of Arniston in the west to the Robberg peninsula in the east. 12 For example, the presence of giraffe 13 , crocodiles 14 , and breeding sea turtles 15 was not suspected from the skeletal record, and has only been established through the presence of their tracks.…”