The tibiotarsus is unusual in that it allowed for the leg to be swivelled backwards and sideways, making it well adapted to reaching into holes and crevices and extracting prey.

[1] A fragment of a femur from the White Hunter site might be referable to the genus on the grounds of its size, age and uniqueness compared to other Australian accipitrids.

[2][3] The Sticky Beak and White Hunter sites are both interpreted as being late Oligocene in age, which would make Pengana one of the oldest known accipitrid from Australia.

Boles (1993) dismissed the idea of a close relationship with Harrier-hawks and Crane hawks, noting that similarities between the three taxa were limited only to the intertarsal joint.

[1] Regardless, Pengana, and the similarly aged Archaehierax, demonstrate that there was at least two different clades of accipitrids present in Australia close to the Oligocene-Miocene boundary.

[5] Features of the intertarsal joint (i.e a more horizontal supratendinal bridge and flattened distal condyles) suggests a greater degree of flexion backwards and sideways than in most acciptirids.

[6] Plant fossils from the late Oligocene or early Miocene-aged Dunsinane site indicate the presence of deciduous vine thickets and sclerophyllous vegetation.