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 : 5

Helladotherium duvernoyi Gaudry, 1861

Specimens. MNHN PIK 1658, MNHN PIK1527 Description. The medial and lateral epicondyles are sub-equal in size, where the medial epicondyle is slightly larger ( Figure 3). The lateral epicondyle is confined. There is a triangular flattened area on the lateral epicondyle, distal to the articular surface. There is an obliquely oriented groove on the lateral epicondyle separating it into two heads ( Figure 4 ). The medial epicondyle is fuller, circle-sector shaped, and extends onto the medial ridge. There is a slight depression on the medial epicondyle, distal to the articular surface. The lateral epicondyle is triangular in shape. There is an obliquely oriented groove on the surface of the medial epicondyle. Both epicondyles are notably flat. There is a deep groove that separates the medial and lateral epicondyles, and continues onto the central trough. The medial ridge has a sharp surface, whereas the lateral ridge has a dish-shaped surface, where the central portion is flattened and concave ( Figure 5.1 ). The central trough is deep and flattens distally ( Figures 6.1 , 7 ). Proximally, the lateral and medial ridges appear approximated towards the midline, which creates an hourglass shape. The medial ridge exhibits an elongated flattened surface on the medial edge. Both ridges completely flatten at the distal third of the shaft. The distal shaft is notably flat. The keels of the distal condyles are confined and do not extend onto the distal palmar shaft.

Figures

FIGURE 4. Three selected metacarpal characteristics. This simplified table can be used to facilitate specimen identifications and differentiate between different giraffid taxa.

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 6. Representative cross sections of right metacarpals. 1, Helladotherium duvernoyi, late Miocene, Pikermi, MNHNP 1527; 2, Birgerbohlinia schaubi, late Miocene, Samos, AMNH 20610 (reversed); 3, Okapia johnstoni, AMNH 15218 (reversed); 4, Samotherium major, late Miocene, Samos, AMNH 22790; 5, Bohlinia attica, late Miocene, Pikermi, PA 1474-1991; 6, Giraffa camelopardalis, AMNH 70016. Scale bar equals 80 mm.

FIGURE 7. Three additional metacarpal characteristics. This simplified table can be used to facilitate specimen identifications and differentiate between different giraffid taxa.