The biology of Pleistocene kangaroos of the genus Congruus is poorly known. Two new specimens with associated postcranial remains from the Thylacoleo Caves, Nullarbor Plain, Western Australia have provided an opportunity to elucidate a more complete picture of the ecology of these animals. The skeletons of the two individuals differ in the robustness and relative development of muscle scars on the humerus and femur, and especially the size of the hands. These features are known to differ between male and female conspecifics in many species of kangaroos and wallabies, and thus likely illustrate sexual dimorphism in this new species. The remarkable preservation of almost the complete postcranial skeleton of these individuals has enabled an ecomorphological analysis of this species. Unexpectedly, the morphology of the postcranial skeleton demonstrates many adaptations for a semi-arboreal lifestyle, particularly in the mobility of the gleno-humeral joint, the development of muscle attachment sites for strong adduction and mobility of the forelimb, and large, robust manual and pedal digits with strongly recurved distal phalanges. These features distinguish Congruus from terrestrial macropodines, but are to some extent convergent with adaptations in tree-kangaroos (Dendrolagus). This discovery, in addition of the two previously described species of Bohra from this area, further highlights the deficiencies in our understanding of the Pleistocene environments of southern Western Australia.