A new species name for Little Foot (StW 573) from Sterkfontein: Australopithecus lenyanlenus

Francis Thackery, ESI  ([email protected])

Martin et al (2025) have examined certain fossils (Fig. 1) which have historically been attributed to either Australopithecus africanus (notably Sts 5, “Mrs Ples”, discovered at Sterkfontein in 1947 and described by Robert Broom and John Robinson) or A. prometheus (notably the holotype, MLD 1, discovered at Makapansgat and described by Raymond Dart in 1948). StW 573 (“Little Foot”, discovered at Sterkfontein by Ron Clarke with Nkwane Molefe and Stephen Motsumi) has been attributed by Clarke and Kuman (2019) to A. prometheus.

Figure 1: Occipital views (Martin et al, 2025) of three hominin crania (StW 573, MLD 1 and Sts 5), annotated by Thackeray (this study). Little Foot (StW 573) is attributed to A. lenyanlenus. Phonetically the latter is prounounced “len-yan-len-us”.

Martin et al (2025) suggest on various grounds that a new species name should be created for StW 573. Assuming that they are correct in stating that this is warranted I propose here the name Australopithecus lenyanlenus, from Northern Sotho lenyane (little) and lenao (foot).

In their brief communication Martin et al (2025) do not consider their selected hominins in the context of chronology. Here is a set of possible dates:

• ​Sts 5 (Mrs Ples)  circa 2 million years (Pickering and Herries, 2020)
• MLD 1  circa 3 million years (McFadden et al, 1979).
• StW 573 (Little Foot)  3.6-3.7 million years (Thackeray, 2024a; Granger et al, 2015).

Figures 2 and 3 present the case of “palaeospectroscopy” for a hominin lineage between Sahelanthropus (circa 7 million years) and Homo sapiens (Thackeray 2019, 2024b). In Fig. 3 MLD 1 (the holotype) retains the name A. prometheus, preceded by Little Foot (A. lenyanlenus) in the blue-green part of a spectrum in a lineage, whereas Mrs Ples (A. africanus) is in the green-yellow component of the spectrum in the same hominin lineage, representing species without boundaries.

Figure 2: A possible hominin lineage, from Sahelanthropus tchadensis to Homo sapiens, without clear boundaries between species (Thackeray, 2024b).

Figure 3: Three hominin fossils (StW 573, MLD 1 and Sts 5) in relation to a possible hominin lineage without clear boundaries between species (Thackeray, 2024b).

References
Clarke R.J. & Kuman K. (2019). The skull of StW 573, a 3.67 Ma Australopithecus prometheus skeleton from Sterkfontein Caves, South Africa. Journal of Human Evolution 134: 102634. https://www.sciencedirect.com/science/article/abs/pii/S0047248418302380
Granger D.E, Gibbon R.J, Kuman K, Clarke R.J, Bruxelles L & Caffee M.W (2015) New cosmogenic burial ages for Sterkfontein Member 2 Australopithecus and Member 5 Oldowan. Nature 522: 85-88. https://www.nature.com/articles/nature14268
Martin, J. M., L. Morris-Obst, A. B. Leece, S. Baker, A. I. R. Herries, and D. S. Strait. (2025). The StW 573 Little Foot Fossil Should Not Be Attributed to Australopithecus prometheus. American Journal of Biological Anthropology 188, no. 4: e70177. https://doi.org/10.1002/ajpa.70177
McFadden P.L, Brock A & Partridge T.C. (1979). Palaeomagnetism and the age of the Makapansgat hominid site. Earth and Planetary Science Letters 44(3):373-382. 
Pickering R & Herries A.I.R (2020). A new multidisciplinary age of 2.61-2.07 Ma for the Sterkfontein Member 4 australopiths. In: B Zipfel, BG Richmond, CV Ward (eds) Hominin Postcranial Remains From Sterkfontein, South Africa, 1936-1995. Oxford University Press, Oxford, UK, pp. 21–30. https://global.oup.com/academic/product/hominin-postcranial-remains-from-sterkfontein-south-africa-1936-1995-9780197507667?cc=us&lang=en& 
Thackeray, J.F. (2019). Hominin palaeo-spectroscopy and sigma taxonomy. PalNews 22 (1): 38-40.
Thackeray F. (2024a). A biochronological date of 3.6 million years for “Little Foot” (StW 573, Australopithecus prometheus from Sterkfontein, South Africa). Evolutionary Anthropology, 33 (6):1-6, e22049. https://doi.org/10.1002/evan.22049
Thackeray, J.F. (2024b). Quantification of morphological variability expressed by a “log sem” statistic in the context of human evolution (Australopithecus, Paranthropus and early Homo). In Les sociétés humaines face aux changements climatiques 3. Proceedings of the International Academy of Prehistory and Protohistory (AIPP), 2023. Pages 1-14. François Djindjian (ed). Archaeopress, Oxford.