Rare footage has emerged from South Africa showing a normally herbivorous giraffe chewing on the bones of another animal.

The surprising moment, which was captured by wildlife photographer Ewan Wilson at Schotia Game Reserve back in November, shows the adult herbivore rolling a bone around in its mouth.

According to experts, feeding on bones provides giraffes with the calcium and phosphorus they need for their own skeletons.

A 2013 study published in the Journal of Archaeological Science found that it's not just bones giraffes feed on. The herbivorous mammals also regularly consume antlers, horns, and ivory.

This behaviour is called osteophagia.