A case of bilateral polydactyly in the grey kangaroo (Macropus giganteus)

We report a case of spontaneous bilateral polydactyly on the upper limbs of a Macropus giganteus (Grey kangaroo). The specimen was an adult male (11 years), and had died from natural causes. The occurrence of polydactyly is exceptional in this species and have not found any other case in the scientific literature. In our specimen there was a supernumerary finger on the anterior side of both forepaws (preaxial polydactyly), a duplicated thumb, inserted between the 1st and the 2nd fingers, with two phalanges, and its corresponding metacarpal bone perfectly ossified, with the proximal articulate surface perfectly flat but showing no contact with the trapezium bone. The space between both bones was occupied by soft tissues. The supernumerary digits of both hands were virtually identical.