Cercopithecoides sp.

Herries, AIR, Menter, CG & Adams, JW, 2015, First description of in situ primate and faunal remains from the Plio-Pleistocene Drimolen Makondo palaeocave infill, Gauteng, South Africa, Palaeontologia Electronica (Basel, Switzerland) 28 (6), pp. 1-21 : 5-7

Cercopithecoides sp. ( Mollet, 1947)

Figure 3 , Table 2

Referred specimens. DNM 1, partial mandible preserving left and right C–P 4; DNM 95, right premaxilla and maxilla preserving I 1 –C.

Description. DNM 1 is a partial mandible preserving the symphysis, the left corpus, and the right corpus to the ascending ramus ( Figure 3.1–2 ; Table 2). Both the left and right C–P 4 are intact, with the left corpus missing posterior to the P 4 and the right corpus preserving the alveolar process for the M 1 –M 3. The right ascending ramus preserves the base, gonion, and the condylar process but lacks a prominentia lateralis. The symphysis is well-buttressed posterior to the incisor alveoli by the superior transverse torus. The corpus is distinctly buccolingually wide at the level of the M 3 alveolus, tapering sharply and distinctly mediolaterally ‘pinched’ on the inferior margin.

TABLE 2. Linear measurements (in mm) of Cercopithecoides sp. teeth. LL = labiolingual, BL = buccolingual, MD = mesiodistal. Boldface indicates article specimens.

Specimen Side I1 LL I1 MD I2 LL I2 MD C1 LL C1 MD C 1 LL C 1 MD P 3 BL P 3 MD P 4 BL P 4 MD DNM 1 Left 5.61 4.55 5.25 7.66 6.75 7.08

DN 861 Right

DN 889 Right

5.19 6.85 7.47

5.49 7.57

DNM 95 Right 5.54 7.66 5.24 6.34 6.79 7.99

The small craniofacial fragment DNM 95 is a complete right premaxilla and small maxillary fragment, preserving the bone to the interpremaxillary suture and I 1, I 2, and canine ( Figure 3.3–4 ; Table 2). The transverse maxillo-premaxillary suture is open, and it is likely that the interpremaxillary suture was also similarly unfused. The tip of the canine root is exposed on its lingual surface in the alveolus and is incompletely closed. There is no wear facet on the canine, and only light occlusal wear on the I 2.

Discussion. The morphology and small size of the canines in both DNM 1 and DNM 95 relative to the adjacent dentition indicates that both specimens are from female individuals. Though roughly similar in size, there is no clear spatial association between the elements and they likely represent two different individuals. The significant manganese crust on the anterior dentition and the lack of postcanine dentition makes establishing age-atdeath for the DNM 1 mandible difficult, beyond noting the original presence of an erupted M 3 suggests minimally an adult individual. While both timing and extent of palatal suture closure in colobines is variable ( Chopra, 1957), the incomplete closure of the canine root in DNM 95 may indicate that the specimen was minimally a late (~M 3 eruption) subadult ( Havarti, 2000).

The genus Cercopithecoides has been recovered from most of the other South African terminal Pliocene and earlier Pleistocene localities (e.g., Makapansgat Member 3, Sterkfontein Member 4, Swartkrans Members 1 and 2, Haasgat, Kromdraai B, Bolt’s Farm; Freedman, 1957; Jablonski and Frost, 2010; Adams, 2012), including the Drimolen Main Quarry ( Keyser et al., 2000). Although South African fossil colobines have traditionally been attributed to the extinct species Cercopithecoides williamsi (with noted variability; Freedman, 1957; Delson, 1984), more recent research has argued for the occurrence of at least three distinct species across these deposits ( McKee et al., 2011; Anderson et al., 2014).

The DNM 1 mandible contrasts with the smaller Cercopithecoides haasgati ( McKee et al., 2011) in overall corpus dimensions of both males and females, including the robusticity of the superior transverse torus. DNM 1 also varies from Main Quarry C. williamsi specimens (DN 861, DN 889) in several features: the absence of a prominentia lateralis (positioned near the mesial root of the M 3 on DN 861), the lack of the buccolingually wide corpus at the M 3 and mediolateral compression of the inferior corpus in both DN 861 and 889, the more buccolingually narrow and mesiodistally elongate P 4 preserved on DN 889, and the greater mesiodistal length of the postcanine toothrow (DN 861). In comparison to similar Cercopithecoides elements, the DNM 1 mandible most closely resembles the Kromdraai B KB 680/686 mandible in possessing a wide and deep symphyseal region, the apparent enlarged postcanine dentition (based on the alveolar process, particularly the buccolingually expanded support for the M 3), and overall corpus morphology (including the planum alveolare and superior transverse torus). The incisive alveolar and superior torus morphology is also similar to that in the Bolt’s Farm female mandible (BF 42b), although we note that the mandibular symphysis of DNM 1 has a steeper slope from alveolus to inferior margin.

The DNM 95 maxilla and premaxilla preserves the lateral margin of the nasal aperture that appears to have been ovoid with a narrow inferior aperture that contrasts the broader nasal aperture shape of C. haasgati . The preserved contour of the nasal aperture of the DNM specimen is most consistent with the ovoid aperture shape of the KB 5241 female cranium, although we note that the KB 5241 inferior margin appears misaligned and may be artificially narrow.

Recently, Anderson et al. (2014) have noted the unique craniodental morphology (metric and non-metric) of the Kromdraai B sample relative to other South African fossil colobines historically placed within C. williamsi . The KB specimens most closely resemble the extinct colobine Cercopithecoides kimeui , a species currently only established at eastern African localities ( Jablonski and Frost, 2010; Anderson et al., 2014), but may represent a novel species (potentially Cercopithecoides coronatus Broom et al., 1950 from the KB 122 neurocranial vault; Freedman and Brain, 1972; Anderson et al., 2014). Until further analysis (and potentially formal separation) of the Kromdraai B sample, we defer attribution of the Drimolen Makondo specimens past the genus level.

Figures

FIGURE 3. Cercopithecoides sp. craniodental specimens from the Drimolen Makondo. 1 and 2, DNM 1, partial mandible; 1, dorsal and 2, right lateral views. 3 and 4, DNM 95, right premaxilla and maxilla; 3, labial and 4, lingual views. Scale bars equal 1 cm.