Helladotherium, Gaudry, 1861

Rios, M, Danowitz, M & Solounias, N, 2016, First comprehensive morphological analysis on the metapodials of Giraffidae, Palaeontologia Electronica 410 (10453), pp. 1-39 : 13

Helladotherium duvernoyi Gaudry, 1861

Specimens. MNHN PIK1564, M 11381 Description. The proximal articular surface exhibits three distinct facets: the lateral facet for the os naviculocuboideum is kidney-shaped. The medial facet for the os cuneiforme intermediolaterale is sub-triangular and is not contacting the os cuneiforme mediale facet, which is oval ( Figure 18.1 ). The medial and lateral epicondyles are symmetrical in size and morphology ( Figure 3). There is a deep groove running obliquely on the lateral shaft, separating the lateral epicondyle into plantar and dorsal heads. The plantar head has a rounded surface which is continuous distally with the lateral ridge. The medial epicondyle is split into two heads by a shallow, obliquely oriented groove on the medial shaft. The plantar head has a full, rounded, elevated surface which is continuous with the medial ridge. In both the medial and lateral epicondyles, the plantar head is oriented longitudinally and the dorsal head flares outward. The medial and lateral epicondyles are separated by a wide, flattened groove. There is no distinct pygmaios ( Figure 16 ). There is an oval, elongated bony protrusion on the medial shaft, which protrudes proximally onto the proximal articular surface. The medial ridge has a secondary elevated ridge on the inner surface. The central trough is deep ( Figure 5.1 ). The pyramidal rise is prominent on the distal shaft and faint at the midshaft. The keels of the distal condyle are confined and do not extend onto the plantar shaft.

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 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.