Late Miocene rhinocerotids from the Balkan-Iranian province: ecological insights from dental microwear textures and enamel hypoplasia

The late Miocene is a period of increasing aridity and habitat openness in the south-eastern Mediterranean region. The impact of these changes has not been fully explored regarding rhinocerotids’ ecology, although rhinoceroses were a major and diverse component of the Miocene mammalian faunas. Here, we investigate the palaeoecology of rhinocerotid specimens coming from 12 localities throughout the Balkan-Iranian zoogeographic province, and covering a large part of the late Miocene (MN9 to MN13). Microwear textures confirmed the hypothesised niche partitioning between the two main rhinocerotid species – Ceratotherium [Ce.] neumayri (mixed-feeder including grasses) and Dihoplus pikermiensis (browser) – but highlighted dietary overlap between Ce. neumayri and the co-occurring chilothere species at Maragheh, Samos and Pentalophos-1. Although microwear did not reveal clear spatiotemporal differences, we found obvious discrepancies regarding hypoplasia prevalence: Vallesian rhinocerotid teeth displayed more defects (Xirochori and Pentalophos-1: 16.26% of teeth affected) than Turolian specimens (all other localities: 9.72%). Similarly, rhinocerotid teeth from eastern localities (Samos and Maragheh; supposedly more arid), had a higher hypoplasia prevalence (13.52%) than their western counterparts (6.90%). Insights from rhinocerotids’ ecology thus challenged space and time homogeneity within Balkan-Iranian province, and the associated savanna habitat, at least regarding the sample studied here.