Paleoenvironments inferred from phytoliths and Dental Microwear Texture Analyses of meso-herbivores

Abstract

The present study aims to assess the environmental conditions that prevailed during the late Miocene in the vicinity of Nikiti 2, Chalkidiki Peninsula (northern Greece). Here, a Dental Microwear Texture Analysis of three species of equids (20 specimens) and six species of bovids (76 specimens) is combined with analysis of the phytolith content of sediments from Nikiti 2. The latter analysis provided few remains of organic silica minerals; some were identified as short cells and are diagnostic of grasses. This is in accordance with previous studies of late Miocene sites in Anatolia which attested to the wide spread of grasslands in the Eastern Mediterranean at that time. Dental Microwear Texture Analysis completes the picture by exploring the diet of herbivores. This analysis concludes that Hipparion sithonis from Nikiti 2 had a diet composed of 80% of grass, making it the most committed to grazing component of the Nikiti 2 fauna. The two other equids from Nikiti 2, H. philippus and H. macedonicum, show affinities with variable grazers and mixed feeders. Among the Nikiti 2 bovids, Nisidorcas planicornis appears to have been a variable grazer and was the bovid most engaged in grazing. At the other end of the spectrum, ?Miotragocerus was least dependent on grasses. The two species of gazelles, Gazella pilgrimi and G. cf. capricornis, are best classified as mixed feeders. Tragoportax amalthea and Palaeoreas lindermayeri both plot between variable grazers and mixed feeders. The absence of browsers and the abundance of grass-eating species within the guild of meso-herbivores exclude the hypothesis of a forest during the late Miocene at Nikiti 2. Instead, it supports the existence of a savanna with grasses in a wealthy herbaceous layer together with accessible dicots (bushes, shrubs and forbs) exploited by medium-sized mammals. The absence of obligate grazers within the meso-herbivore guild suggests severe and repeated depletions of grassy vegetation (likely during seasonal droughts) forcing herbivores to widen their feeding habits to include browse. Such seasonality in food resources is consistent with paleoclimatic evidence especially with respect to seasonal changes in temperature.