The well-preserved tracks were left in the silt by a species of bird that would have made even today's ostriches seem tame.
The streets of Chongzuo City were filled with large flightless birds at the weekend after 80 ostriches escaped from a local farm.
A gargantuan species of ostrich-like elephant bird from Madagascar was thought to the largest that ever lived.
Scientists have discovered the world's oldest genetic information within 3.8 million-year-old eggshells.