Eurygnathohippus, van Hoepen, 1930

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 : 17

Genus EURYGNATHOHIPPUS van Hoepen, 1930

Type species. Eurygnathohippus cornelianus van Hoepen, 1930 .

cf. Eurygnathohippus cornelianus van Hoepen, 1930

Figure 7

Referred material. DNM 13, left proximal fourth metacarpal.

Description. The DNM 13 partial left fourth metacarpal preserves a robust proximal epiphysis and a portion of a gradually narrowing diaphysis ( Figure 7.6–7 ). Proximally, the epiphysis flares laterally, with a D-shaped articular surface that is bisected mediolaterally by a slight ridge dividing the surface into two subtriangular facets. The proximal diaphysis is nearly triangular in cross section, with marked rugose faceting on the medial aspect for the third metacarpal. At the point of breakage, the distal end of the diaphysis is still relatively robust and ovoid in cross section.

Discussion. There is a paucity of hipparionin postcrania in the South African fossil record, which makes direct comparison difficult. However, although not representing the equivalent element, the DNM 13 fourth metacarpal is appropriately sized for articulation with the G 2636 right third metacarpal, and similarly sized to the Gondolin GD 2 second and fourth metapodials (G 3309, G 6549) as well as the SKX 6778 second metatarsal ( Churcher and Watson, 1993; Adams and Conroy, 2005; Adams, 2006).

Currently DNM 13 is the sole identifiable perissodactyl element from the Makondo deposits and the only equid described from the Drimolen site ( Keyser et al., 2000). Although hipparionins are rarely recovered from South African terminal Pliocene and early Pleistocene deposits, craniodental and postcranial remains have been recovered from Cornelia-Uitzoek, Makapansgat Member 3, Kromdraai A, Swartkrans Members 1– 3, and Gondolin GD 2 ( Churcher, 1970; Reed, 1996; Churcher and Watson, 1993; Adams, 2006; Bernor et al., 2010; Brink et al., 2012). Currently the only genus and species of hipparion equid established from craniodental remains within contemporary Plio-Pleistocene deposits of South Africa is Eurygnathohippus cornelianus (and lineage; Bernor et al., 2010). Although the recovered element is not generically or specifically identifiable per se, this is the most likely attribution for the specimen given the currently understood hipparionin biogeography.

Figures

FIGURE 7. Artiodactyla and Perissodactyla from the Drimolen Makondo assemblage. 1 and 2, DNM 143-1, Hippotragus sp. partial horn core; 1, lateral and 2, anterior views. 3–5, DNM 57, Metridiochoerus sp. right maxillary third premolar; 3, lingual, 4, occlusal, and 5, buccal views. 6 and 7, cf. Eurygnathohippus cornelianus left proximal fourth metatarsal; 6, medial and 7, posterior views. Scale bars equal 1 cm.