The postcranial skeleton of the Miocene kangaroo,Hadronomas puckridgiWoodburne (Marsupialia, Macropodidae)

Hadronomas was a large kangaroo similar in size to Simosthenurus occidentalis. Its pes was relatively long and robust, resembling those of the sthenurines Procoptodon and Sthenurus in possessing ligamentous specialisations of the fourth proximal phalanx, anteroposterior compression of fourth proximal and median phalanges, broad, blunt ‘hoof-like’ terminal fourth phalanx, a shallow calcaneocuboidal ‘step’, anteroposterior as opposed to mediolateral differentiation of the ankle joint, high, rounded profile of the astragalar trochleae and a reduced, medially situated proximal ventromedial facet of the cuboid. The upper and lower limb girdles resemble those of sthenurines in that the coracovertebral angle of the scapula is elevated and produced anteriorly in the form of a rectangular process. The innominate is anteroposteriorly broad and the ischium is flattened in cross section. The tibia possesses a sinuous shaft and an elongated, smoothly convex tibial crest that tapers gradually into the diaphysis. Hadronomas's postcranial skeleton differs from other sthenurines in retaining a large functional fifth digit and in showing no proximodistal compression of the cuboid. A character analysis of the postcranial skeleton of Hadronomas indicates that the genus represents a primitive member of the Sthenurinae, and that the Sthenurinae and the Macropodinae diverged at an early stage in macropodid evolution.