Dorcatherium naui and pecoran ruminants from the late Middle Miocene Gratkorn locality (Austria)

Abstract

One of the rare records of a rich ruminant fauna of late Middle Miocene age (Sarmatian sensu stricto; 12.2–12.0 Ma) was discovered at the Gratkorn locality (Styria, Austria). It comprises, besides Micromeryx flourensianus, ?Hispanomeryx sp., Euprox furcatus, Palaeomerycidae gen. et sp. indet., and Tethytragus sp., one of the oldest records of Dorcatherium naui. Gratkorn specimens of the latter species are in metric and morphologic accordance (e.g. selenodont teeth, bicuspid p2, non-fusion of malleolus lateralis and tibia) with type material from Eppelsheim (Germany) and conspecific material from Atzelsdorf (Austria), and do not show an intermediate morphology between Late Miocene Dorcatherium naui and Middle Miocene Dorcatherium crassum, thus enforcing the clear separation of the two species. It furthermore confirms the assignation of Dorcatherium naui to a selenodont lineage (together with Dorcatherium guntianum) distinct from a bunoselenodont lineage (including Dorcatherium crassum). The record of ?Hispanomeryx sp. is the first of this genus in Central Europe. While Tethytragus sp. could also be a new bovid representative for the Sarmatian of Central Europe, Micromeryx flourensianus and Euprox furcatus are well-known taxa in the Middle Miocene of Central Europe, but comprise their first records from Styria. Morphological data from this work in combination with isotopic measurements (δ18OCO3, δ13C; Aiglstorfer et al. 2014a, this issue) indicate a niche partitioning for the ruminants from Gratkorn with subcanopy browsing (Euprox furcatus), top canopy browsing (Tethytragus sp.) and even a certain amount of frugivory (Dorcatherium naui and Micromeryx flourensianus).