An Exceptional Collection of Early Pleistocene Bustards (Aves: Otididae) and a Review of Fossil Pre-Middle Pleistocene Eurasian Otididae

The family Otididae (bustards) is one of the oldest groups of extant neoavian birds with a very patchy fossil record and almost unknown evolutionary history. This paper describes an exceptional collection of Early Pleistocene (1.8–1.6 Ma) bustards of two taxa from the Taurida cave in Crimea (Eastern Europe), which enables the first detailed morphological characterization of the poorly known large-sized species Otis lambrechti, confirming its validity and osteological distinction from the modern Great Bustard (Otis tarda). A rich sample of the smaller taxon Tetrax kalmani shows this fossil species to be consistently larger than its modern relative, the Little Bustard (Tetrax tetrax). A comprehensive critical review of Eurasian fossil Otididae, correcting previous misidentifications, is also provided. The new fossil evidence suggests that the Early Pleistocene bustard fauna of Europe was composed of morphologically distinct taxa, which were later replaced by their modern counterparts around the Middle Pleistocene, probably as a result of the mid-Pleistocene climate transition.