Bramatherium megacephalum Lydekker, 1876

Rios, M, Danowitz, M & Solounias, N, 2016, First comprehensive morphological analysis on the metapodials of Giraffidae, Palaeontologia Electronica 410 (10453), pp. 1-39 : 14

Bramatherium megacephalum Lydekker, 1876

Specimen. AMNH 19688

Description. The proximal articular surface exhibits three distinct facets. The lateral facet for the os naviculocuboideum is oval-shaped. The medial facet for the os cuneiforme intermediolaterale is semicircular in shape and is not contacting the os cuneiforme mediale facet ( Figure 18.2 ). The medial epicondyle is split into a dorsal and plantar head by a longitudinal groove on the medial shaft ( Figure 5.2 ). The plantar head is small with a rounded surface, and the distal aspect continues onto the medial ridge. The lateral epicondyle is split into a dorsal and plantar head by a longitudinal groove on the lateral shaft. The plantar head is more expansive and triangular with a flattened surface, and is continuous distally with the lateral ridge. Both heads of the lateral and medial epicondyles are oriented longitudinally, however the dorsal heads slightly flare outward ( Figure 16 ). On the proximal medial shaft, there is a small circular bony protrusion separated from the rest of the shaft by a narrow groove ( Figure 8 ). This is confined to the proximal shaft and is visible at the medial proximal articular surface ( Figure 17). At the proximal lateral shaft, there is a large oval bony protrusion, which is completely separated from the lateral epicondyle and shaft. It is oriented obliquely towards the plantar shaft. The pygmaios is rounded and oriented towards the medial side ( Figure 16 ). The medial and lateral ridges are sharp. The central trough is intermediate in depth, and it flattens at the distal shaft. The distal shaft flares laterally. The keels of the distal condyles extend onto the distal shaft medially, but are confined laterally.

Figures

FIGURE 5. Palmar views of the right metacarpals (left) and plantar views of metatarsals (right) of certain Giraffidae. 1, Helladotherium duvernoyi, late Miocene, Pikermi, NHM 11382 (metacarpal), MNHNP 1554 (metatarsal) (both reversed); 2, Bramatherium megacephalum, late Miocene-Pliocene, Siwaliks, AMNH 29820, (metacarpal), AMNH 19668 (metatarsal); 3, Sivatherium giganteum, Pleistocene, Siwaliks, NHM 39553 (metacarpal), NHM 39752 (metatarsal); 4, Decennatherium pachecoi, late Miocene, Los Valles de la Fuentidueña, MNCN 42769 (metacarpal), MNCN 42764 (metatarsal) (both reversed); 5, Birgerbohlinia schaubi, late Miocene, Piera, IPS 5060 (metacarpal), Crusafont, 1952, fig. 15-5 (metatarsal), (both reversed); 6, Okapia johnstoni, Zaire, AMNH 51196 (metacarpal), AMNH 51196 (metatarsal). Scale bar equals 200 mm.

FIGURE 8. Bramatherium megacephalum from the Upper Siwaliks. 1, Right metacarpal AMNH 29820; 2, Right metatarsal AMNH 19688.

FIGURE 16. Three selected metatarsal characteristics. This simplified table can be used to facilitate specimen identifications and differentiate between different giraffid taxa.

FIGURE 18. Metatarsal proximal morphology. 1, Helladotherium duvernoyi, late Miocene, Pikermi, M 1138; 2, Bramatherium megacephalum, late Miocene-Pliocene, Siwaliks, AMNH 19688; 3, Decennatherium pachecoi, late Miocene, Los Valles de Fuentidueña, MNCN 42764; 4, Birgerbohlinia schaubi, late Miocene, Piera, IPS 5090. Abbreviations: NC, os naviculocuboideum facet; CIL, os cuneiforme intermediolaterale facet; CM, os cuneiforme mediale facet. Images not to scale.