A new species of bristlebird (Passeriformes, Dasyornithidae) from the early Miocene of Australia

ABSTRACT

The bristlebird family (Passeriformes, Dasyornithidae) constitutes one of the earliest branches in the oscine (songbird) tree. A new bristlebird, Dasyornis walterbolesi, sp. nov., is described from lower Miocene deposits of the Riversleigh World Heritage Area, Australia. This new species is based on a femur, a tibiotarsus, and a tarsometatarsus of one individual, the first known instance of associated passerine bones in the pre-Pleistocene record of Australia, as well as a distal part of a femur of a second individual. Dasyornis walterbolesi is smaller in size than the extant eastern bristlebird, D. brachypterus, and extends the known fossil record for Dasyornithidae by 18 million years. The new fossils considerably increase the geographic range of Dasyornithidae and indicate that the bristlebird family was once more widespread in Australia. A phylogenetic analysis of 91 morphological characters strongly supports the placement of the new fossil species in Dasyornithidae, although its intrafamilial relationships will only be better informed by discovery and study of additional material. Dasyornis walterbolesi meets five criteria for consideration as a well-justified fossil calibration and can be used to calibrate molecular estimates of the passerine evolutionary timescale.

ACKNOWLEDGMENTS

I thank S. Ingleby and L. Tsang (AM), L. Joseph and A. Drew (ANWC), A. Tennyson and T. Schultz (NMNZ), K. Roberts (NMV), and P. Horton and M. Penck (SAMA) for access to comparative specimens. I am indebted to M. Archer and S. Hand (UNSW) for access to fossil specimens, and to A. Gillespie (UNSW), who carried out skilled fossil preparation. The Riversleigh project was supported by the Australian Research Council (grants DP130100197, DE130100467, DP170101420 to M. Archer, S. Hand, and K. Black); XSTRATA Community Partnership Program (North Queensland); University of New South Wales; Queensland Parks and Wildlife Service; Environment Australia; Queensland Museum; Riversleigh Society Inc.; P. Creaser and the CREATE Fund; Outback at Isa; Mount Isa City Council; Associated Scientific Ltd.; the Waanyi people of northwestern Queensland; private supporters; and the field assistance of staff, postgraduate students, and volunteers. I thank P. Schouten for the artistic reconstruction of the new fossil bird. I also thank W. Longmore for informative discussions and T. Worthy for helpful comments that improved an earlier draft of the manuscript; and the editor V. De Pietri, G. Mayr, and an anonymous reviewer for their constructive feedback. This work was supported by the Linnean Society of New South Wales (Betty Mayne Scientific Research Fund for Earth Sciences) and in part by a Chadwick Biodiversity Fellowship (AM) to J.N.