Late Miocene rails (Aves: Rallidae) from southwestern Russia

Abstract

The Miocene was an important period for the assembly of present-day avian faunas of the North Temperate Zone. Details of this process, however, remain largely unexplored due to the scarcity of diverse late Miocene avian localities throughout the Eurasian continent. Here, we present a survey of the osteological diversity of extant rails and, based on these results, assess the diversity of rails from the late Miocene (7.5–7.1 Ma) locality Morskaya-2 in the south of European Russia. We document three taxa, two of which are described as Crexica crexica gen. et sp. nov. and Miohypotaenidia tanaisensis gen. et sp. nov. These taxa show affinities with the modern species Crex crex and Hypotaenidia (Gallirallus) philippensis respectively and thus may represent the oldest records of the Crex and Hypotaenidia-Gallirallus lineages in the fossil record. The taxonomic composition of rails from Morskaya-2 locality considerably differs from that observed at the roughly coeval locality Polgardi in Hungary, which likely reflects palaeogeographic differences during the late Miocene in Europe. Although Central Europe was already inhabited by modern-type rails in the late Miocene, more ancestral groups were present in the East. Some other aspects of the evolution of the modern fauna of Rallidae are discussed.