Palaeotragus

Palaeotragus was an extinct giraffid of the Old World, best known from Late Miocene fossils in Greece and neighbouring regions. Its skull carried one pair of relatively simple ossicones above the eyes, and its limbs were long and slender. The neck was longer than in most ordinary hoofed mammals but did not reach the extreme proportions of a living giraffe. The genus belongs in the ice-age animal catalogue, whose coverage includes lineages that began before the Pleistocene.

The name has covered a changing set of species. Fossils once grouped together on the basis of resemblance have been reassessed using ossicones, teeth, skulls and limb bones. That history makes it important to distinguish the well-known type species from less secure assignments.

Quick facts

A genus named at Pikermi

Albert Gaudry established Palaeotragus in 1861 from material at Pikermi near Athens. The Late Miocene locality became famous for a rich assemblage of hoofed mammals and carnivores. The type species, P. rouenii, is represented by cranial and postcranial remains, which offer a firmer basis for reconstruction than a taxon known from an isolated tooth alone.

During the nineteenth and twentieth centuries, similar giraffids from Europe, Asia and Africa were often assigned to this genus. It became a convenient grouping for forms with two fairly simple ossicones. Modern revisions consider the skull, teeth, ossicones, limb proportions and neck together. When only one anatomical system is known, a placement may remain provisional.

For example, the Middle Miocene Mongolian species Palaeotragus tungurensis was described from a partial skull and jaws without an ossicone securely associated with them. A later ossicone from the same formation showed features attributed to a separate giraffid lineage, Bohlinini, prompting reassessment of the old generic assignment. Fossils from one region or formation do not automatically belong to the same animal just because they were found nearby.

Ossicones are not ordinary horns

Giraffid ossicones differ from the hollow horns of bovids. In living giraffes, they develop as separate ossifications in the skin and later fuse with the frontal bones. The precise developmental history in palaeotragines is debated; some authors interpreted their structures as outgrowths of the frontal bone.

In typical Palaeotragus, a pair of ossicones stood above the eyes, set relatively close to the sides of the skull. Their rough lower portions were probably covered by skin. The tips on a Late Pleistocene specimen referred to P. inexspectatus are smooth, a condition compared with wear on exposed tips in the living okapi. Similar soft coverings are not directly preserved across all species.

Large ossicones on some skulls have been interpreted as a male feature by comparison with other giraffids. Sexual dimorphism is plausible, but the sex of one fossil cannot be diagnosed from a large pair of bones without a population sample showing consistent differences.

Skull, teeth and feeding

The skull was broad and relatively flat across its upper surface. Its cheek teeth had moderately low crowns and crescentic enamel ridges typical of ruminants. This pattern fits leaves and shoots better than constant processing of abrasive dry grass, but tooth shape alone cannot specify every plant eaten.

In the Early Pleistocene form P. inexspectatus, premolars accounted for about 42 per cent of cheek-row length, while the crowns remained moderately brachydont. That species was larger than the type species P. rouenii; its measurements should not be transferred to every member of the genus. No stomach contents are known. A reconstruction showing an animal browsing high in a tree is an ecological scene, not a preserved feeding observation.

Neck and limbs

Like other giraffids, Palaeotragus had seven neck vertebrae. Neck lengthening came from changes in the proportions of individual vertebrae, not from adding extra ones. The cervical series is incomplete for the genus, so a simple comparison such as “half the length of a giraffe’s neck” is not a measured rule.

The fused third and fourth metatarsals formed a long cannon bone. Its limbs were suited to steady walking and running on firm ground. An Early Pleistocene find from Sesklon in Greece includes a 335 mm metapodial fragment lacking its joint ends and a robust atlas vertebra consistent with a strong neck. Those pieces constrain anatomy without supplying a complete skeleton of one individual.

The giant Sivatherium had a much heavier body and a more elaborate set of ossicones. It was a separate giraffid branch, not an adult form of Palaeotragus. Comparison with the North American camelid Aepycamelus also illustrates that long-legged browsing builds evolved in different hoofed-mammal lineages.

From the Miocene into the Pleistocene

Classic species of Palaeotragus lived in the Late Miocene. Material from Sesklon, Dmanisi in Georgia and other Early Pleistocene localities has been referred to P. inexspectatus. A nearly complete skull from Sesklon preserves ossicones, teeth and the rear of the skull; an atlas and a metapodial were also recovered nearby.

Researchers regard these Early Pleistocene finds as part of a palaeotragine lineage, but their generic placement has shifted among Palaeotragus, Mitilanotherium and other names. It is therefore inaccurate to say that one unchanged genus lived continuously for tens of millions of years. The familiar outline represents a group of related fossils whose classification has been revised.

Limits of reconstruction

The paired simple ossicones, giraffid skull, long limbs and moderately elongated neck are supported by bones. A coat patterned like an okapi or giraffe, tufts on the ossicones, mane length and social structure are unknown. Different species assigned to the genus may have differed substantially in size, so one illustration cannot represent the entire historical membership.