David Marjanovic wrote:
Before 1997, there was no evidence for carnivory, and dromornithids were regarded as herbivores, but then the enormous skull of *Bullockornis planei* was discovered.
Stephen Wroe (1999): Killer Kangaroos and Other Murderous Marsupials. Scientific American, May 1999.
BTW, *Gastornis* ( = "*Diatryma*") is now also considered to have been carnivorous -- the skull is seriously overdesigned for herbivory, and yet it is more gracile than that of *Bullockornis* aka "The Bird from Hell" aka "The Demon Duck of Doom".
Raymond Thaddeus C. Ancog Mines and Geosciences Bureau Philippines