The sudden extinction of giant apes is an "enigma in paleontology," one scientist said, but new research proposes an answer to why they disappeared.

Some 330,000 years ago, giant apes the size of elephants roamed the forests of southern China. Their massive teeth—once sold as a “dragon tooth” by a Hong Kong apothecary—gnawed tough leaves and devoured fruit. Then suddenly, while other primates were thriving, these supersized orangutan-like creatures vanished with almost no trace.