Dietary adaptations and paleoecology of the Late Miocene ruminants from Pikermi and Samos in Greece

Abstract

The late Miocene (Turolian) localities of Pikermi and Samos in Greece present numerous ruminant species which have been interpreted to represent savanna-adapted taxa. The masticatory morphology of these extinct ruminants is compared qualitatively to twenty-seven extant ruminant species from Asia and Africa using thirteen masticatory features. Statistical analysis of these features on the modern species shows significant differences between the morphology of browsers, intermediates and grazers and suggests that intermediate and grazing adaptations evolved independently more than once. In addition, certain extant ruminant browsers and intermediates may have assumed such diets from ancestral grazing species recently. Application of this method to the extinct species from Pikermi and Samos shows that, with the exception of one species, the bovids were either browsers or intermediates. Parurmiatherium rugosifrons from Samos was probably the only grazer. Pachytragus laticeps, a presumably advanced species, has masticatory morphology very similar to Miotragocerus species, commonly interpreted as primitive species. Samotherium boissieri and Helladotherium duvernoyi were intermediate feeders, although giraffids. We propose that the absence of grazers at these localities suggests that savanna-like dietary adaptations for ruminants were not as widespread as now. The presence of savannas similar to those of East Africa at Pikermi, Samos and other Miocene localities is unlikely. Such savannas were originally proposed because of modernization of fossil taxa, the presence of numerous ungulate and hyaenid species, the misconception that hipparions represent zebra-like species, and the abundance of fossil specimens. Ruminant faunal comparisons using masticatory morphology point out a greater similarity of Pikermi and Samos to extant forest and woodland ruminants; the extinct ruminant faunas were not similar to extant savanna-adapted species. A good physiognomic model for the Pikermi-Samos ruminants is the forest-woodland ruminants of Sichuan, China, Southeast Asia, and Kanha, India. The hypothesis that the Pikermi ruminants evolved in forested environments is supported by analysis of the local paleofloras. The Pikermi is similar to modern warm mixed riparian evergreen and broadleaf deciduous temperate woodland-forest. The Turolian mountains near Pikermi had mixed forests, although evergreens dominated.