Osteology of a new giant bony-toothed bird from the Miocene of Chile, with a revision of the taxonomy of Neogene Pelagornithidae

ABSTRACT Bony-toothed birds (Pelagornithidae) were among the largest volant birds, but their representatives from the upper size range have so far been known only from very fragmentary fossils. Here we report an exceptionally well-preserved giant species from the late Miocene of the Bahía Inglesa Formation in northern Chile, in which most major limb bones are complete and uncrushed. The fossil has the longest wing skeleton of any bird, and its wingspan in life was at least 5.2 m. Mass estimates of 16–29 kg are, however, surprisingly low and within the range of large extant volant birds, or only moderately above. The fossil constitutes the most substantial record of the Pelagornithidae (bony-toothed birds), and is assigned to a new species, Pelagornis chilensis. It is one of the largest known pelagornithids and the three-dimensionally preserved bones allow recognition of many previously unknown osteological features, especially concerning the vertebrae, pectoral girdle, and limb elements. We revise the taxonomy of Neogene pelagornithids and propose classification of all Miocene and Pliocene species into a single genus, Pelagornis. Osteological features are highlighted in which giant Neogene Pelagornithidae differ from their smaller Palaeogene relatives. ACKNOWLEDGMENTS We thank C. Gomez, S. Nielsen, B. Pohl, V. Mosbrugger, and G. Zizka for assistance in the acquisition of the fossil, R. Ellenbracht, A. Elżanowski, A. Manegold, S. Walsh, and C. Gutstein for discussions, and S. Tränkner for taking the photographs. Reviews by P. Scofield and T. Worthy improved the manuscript. Notes aAfter CitationMourer-Chauviré and Geraads (2008). bAfter CitationLambrecht (1930). cEstimation based on CitationLambrecht (1930:fig. 1). dAfter CitationHoward and Warter (1969). eAfter CitationHoward (1957). fUnnamed species from the Miocene of Japan; after CitationOno (1989). aFrom tip of processus acrocoracoideus to angulus medialis. bAfter CitationMourer-Chauviré and Geraads (2008). cUnnamed species from the Pisco Formation (Peru); after CitationChávez et al. (2007). dAfter CitationHoward (1957). aAfter CitationMourer-Chauviré and Geraads (2008). bUnnamed species from the Miocene or Pliocene of North Carolina; after CitationOlson and Rasmussen (2001). cUnnamed species from the Pliocene of Japan; after CitationOno (1980). dAfter CitationHoward and Warter (1969). eAfter CitationHoward (1957). fAfter CitationHopson (1964). gAfter CitationWetmore (1928).