An ancient mega ape's massive size — clocking in at 10 feet tall and around 550 pounds — turned into an evolutionary disadvantage as it went extinct more than 200,000 years ago, according to new study published in Nature on Wednesday.

Why it matters: The new research helps scientists resolve a longstanding mystery surrounding the legendary Gigantopithecus blacki's disappearance from what's now China.

What's happening: Gigantopithecus blacki, the largest known primate to roam Earth, went extinct between 295,000 and 215,000 years ago because it failed to adapt to a changing climate.

• The region between the Yangtze River and the South China Sea had been ideal for populations of the massive ape for millions of years until its climate began to shift, becoming increasingly dry and divided by seasons, the researcher proposed.

Zoom in: The nearly year-round fruit that Gigantopithecus had relied on became scarcer in this altered environment, forcing them to shift their diets.

• Signs of chronic stress on Gigantopithecus teeth from this period suggest the species turned to highly fibrous — but less nutritious — fallback foods when their preferred food was unabundant.
• The dental wear also suggests their dietary diversity shrunk and that the species consumed less water.
• As a result of their dietary behaviors, the apes likely became less mobile, meaning their foraging range was reduced, and populations of the apes began to decline.

Between the lines: The new study not only reveals the fate of one of humanity's distant ancestors but also shows that environmental triggers can readily kill off even a gargantuan species that had already existed for millions of years.

What they're saying: Yingqi Zhang, a co-lead author of the new research and a paleontologist at the Chinese Academy of Sciences, said in a statement that the disappearance of Gigantopithecus had been an "enigma" in paleontology.

• "How could such a mighty creature go extinct at a time when other primates were adapting and surviving?" he said.

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