New hominin cranial and mandibular remains from Drimolen Main Quarry, South Africa.

Abstract

Background: To date, the only specimens to have been comprehensively described from Drimolen Main Quarry (DMQ) are dental elements, well preserved crania (DNH 7, DNH 134, DNH 152, DNH 155), and 29 post-cranial elements. Consequently, a significant number of hominin fossils, some excavated over 30 years ago, remain completely or partially undescribed and therefore unavailable for study.

Aim: To describe the bony anatomy of a further 18 cranial specimens excavated between 1992 and 2019. We additionally utilise these newly described specimens to test existing hypotheses concerning the first appearance of H. erectus at DMQ ∼2.0 Ma, and the morphological distinctiveness of the DMQ P. robustus ukusa sample.

Subjects and methods: We adopt the methods of descriptive morphology by comparing DMQ hominin fossils to hominin fossil samples from SM1HR and KBM4-6. We utilise qualitative anatomical descriptions and comparisons, supplemented with quantitative measurements.

Results: Of the 18 previously undescribed DMQ hominin fossils, we assign one to Homo erectus, 14 to Paranthropus robustus, and three to Hominini gen. et sp. Indet. Additionally, we identify a new mandibular trait which may further discriminate DMQ P. robustus from SM1HR and KBM4-6.

Conclusion: The morphology preserved by these additional Paranthropus robustus fossils is compatible with the hypothesis that the DMQ population is morphologically distinct from the SM1HR and KBM4-6 populations. Further, DNH 127 provides additional evidence for the presence of H. erectus in South Africa at ∼2.04-1.95 Ma.