The giant accipitrid Dynatoaetus gaffae gen. et sp. nov. is described from existing and newly collected material. Initial fossil remains were collected from Mairs Cave (Flinders Ranges, South Australia) in 1956 and 1969, and comprised a sternum, distal humerus and two ungual phalanges. A further 28 bones from this individual—including the neurocranium, vertebrae, furculum, and additional wing and leg bones, most of which were incomplete—were discovered at the site in 2021. This allowed identification of additional fossils from the same species in collections from Cooper Creek (Lake Eyre Basin, SA), Victoria Fossil Cave (Naracoorte, SA) and Wellington Caves (Wellington, NSW). Dynatoaetus has variable similarity across elements to those of living species in the Perninae, Gypaetinae, Circaetinae and Aegypiinae. Parsimony and Bayesian phylogenetic analyses of combined morphological and DNA data resolved it as the immediate sister-group to the Aegypiinae within the Circaetinae + Aegypiinae clade. The robust and eagle-like morphology of the lower hindlimbs suggest that the species was a predator, rather than a scavenger, and thus functionally similar to large circaetines such as the Philippine Eagle Pithecophaga jefferyi. Furthermore, this new species is the largest known bird of prey from Australia, much larger than the modern Wedge-Tailed Eagle Aquila audax. It is outsized in Australasia only by female Hieraaetus moorei (the extinct Haast’s Eagle from New Zealand). It is inferred to have been Australia’s top terrestrial avian predator during the Pleistocene, ranging from arid inland Australia to the more temperate coast, and likely became extinct around the time of the megafaunal mass extinction which peaked around 50 Ka. Its extinction in the late Pleistocene, along with the recently described scavenging vulture Cryptogyps lacertosus, marked a distinct decline in the diversity and function of Australia’s raptor guild.

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