Browsing and non-browsing extant and extinct giraffids: Evidence from dental microwear textural analysis

Abstract

Today, the family Giraffidae is restricted to two genera endemic to the African continent, Okapia and Giraffa, but, with over ten genera and dozens of species, it was far more diverse in the Old World during the late Miocene. We attempt to describe here how several species may have shared feeding resources in the Eastern Mediterranean. Dietary preferences were explored by means of Dental Microwear Textural Analysis in combination with estimation of body mass and the maximum height at which the various species were able to browse.One of our main results concerns the modern okapi, Okapia johnstoni. It is a forest dweller usually regarded as a browser, but we show that it might also forage on tough plants, possibly herbaceous monocots. Such feeding habits including portions of herbaceous monocotyledons were also found for some extinct species, especially the genera Samotherium and Palaeotragus. Palaeogiraffa shows a contrasted pattern: the specimens of P. pamiri from a site in Thrace were leaf-dominant browsers whereas those belonging to P. major and P. macedoniae from the Axios valley in Greece ingested herbaceous monocotyledons. Helladotherium duvernoyi, the only sivatheriine analyzed here is described as a leaf-dominant browser. The giraffine Bohlinia attica also falls within the leaf-dominant browser category but could browse on higher foliages than H. duvernoyi. On the whole, the reconstructed diets confirm the relationship between more grazing habits and smaller premolars, but not with higher dental crown height.