Cercopithecidae, Gray, 1821

Gommery, Dominique, Kgasi, Lazarus, Vilakazi, Nonhlanhla, Sénégas, Frank, Pickford, Martin, Kuhn, Brian, Schnyder, Johann & Pois, Véronique, 2023, First in situ middle Pliocene cercopithecoid fossils from the Palaeokarst System of Bolt’s Farm (South Africa), Geodiversitas 45 (5), pp. 163-195 : 183-184

Cercopithecidae indet.

MATERIAL EXAMINED. — Mandible. BPB 8 ( Fig. 22A, B ); BPB 26 ( Fig. 22C, D ). — Postcranial bone. BPB 19 ( Fig. 22E, F ).

DESCRIPTION

Mandible

BPB 8 ( Fig. 22A, B ). This fossil (maximum length: 20.8 mm; height: 20 mm) is the distal part of the ascending ramus and the mandibular condyle of a right mandible. The median part of the condyle is damaged and the lateral part is very salient (length: 9.3 mm; breadth: 16.6 mm).

BPB 26 ( Fig. 22C, D ). The preserved part (maximum length: 26.1 mm; height: 24.7 mm) comprises the ascending ramus and the mandibular condyle (maximum length: 7.8 mm; preserved breadth: 6.4 mm) of a right mandible.

Post-cranial bone

BPB 19 ( Fig. 22E, F ). This right intermediate manual phalanx presents a big crack latero-distally to medio- proximally and it has lost a fragment latero-distally and a dorsal flake of bone latero-proximally which has damaged the proximal articular facet. The phalanx is short and presents a flat aspect (length: 15 mm; mid-shaft thickness: 3.2 mm). The intermediate phalanges of the hand and foot of colobines and Papio present nearly the same size and almost the same aspect except that they are slightly flatter in the hand ( Begun et al. 1994). The proximal extremity is slightly larger (preserved breadth: 6.9 mm, height: 5.4 mm) than the distal extremity (breadth: 6.1 mm, height: 4.1 mm). The proximal articular facet presents a double concavity as is usual in a median phalanx. In dorsal view ( Fig. 22E ), a small hole is present in the distal extremity and corresponds probably to a predator mark. In volar view ( Fig. 22F ), along all the shaft, there are extensions underlined by deep depressions which correspond to the insertion of collateral ligaments of the manual interphalangeal joint. The central part of the shaft is convex medio-laterally and forms a pillar. The proximal extremity presents a smooth bulge on each side. There is a small oval cavity which possibly corresponds to a mark of predation. The distal extremity presents a trochlear aspect. In plantar view, the medial condyle of this trochlea is the narrower and the more convex of the two condyles. It is not possible to say more about this phalanx.

Figures

FIG. 22. — A, B, Distal part of the ascending ramus of a right mandible of Cercopithecidae indet., specimen BPB 8: A, lateral view; B, distal view; C, D, distal part of the ascending ramus of a right mandible of Cercopithecidae indet., specimen BPB 26: C, lateral view; D, medial view; E, F, right intermediate manual phalanx of Cercopithecidae indet., specimen BPB 19: E, dorsal view; F, volar view. Scale bar: 10 mm.