Pengana robertbolesi, a fossil raptor from the Tertiary of Riversleigh, northwestern Queensland, shares with the living generaPolyboroidesandGeranospizaa distinctive morphology of the distal tibiotarsus. The modified structure of the intertarsal joint permits a much greater degree of both anterioposterior and mediolateral flexion than in other species of the Accipitridae. Living species employ acrobatic foraging methods, using the flexible leg to probe hollows and recesses. It is considered thatP. robertbolesiused similar foraging techniques. Because it was approximately twice the size of living taxa, it probably was capable of predating substantially larger prey.