Two passeriform birds (Aves: Passeriformes) from the Middle Miocene of Austria

Abstract

Two newly discovered specimens of passerine birds—an isolated sternum and an associated skeleton—from the upper Middle Miocene (ca. 12 Ma) are the oldest representatives of Passeriformes from Austria. Although the condition of the specimens prevents their accurate identification, they provide further clues on the morphological diversity of the avifauna during this period and fill gaps in the paleobiogeography of Miocene passerines. The associated skeleton represents a bird similar in size to the extant Sylvia atricapilla or Erithacus rubecula, and the delicate beak indicates that the bird fed mainly on small invertebrates and possibly also soft fruit. The isolated sternum belonged to a small thrush-sized bird and, considering the fragility of this skeletal element, is one of the best-preserved Miocene passerine sterna in the world.