Researchers have linked the development of the human jaw to a 423-million-year-old armoured fish that skulked the bottom of the oceans.
Paleontologists from China and Sweden said Thursday that our jaws can be traced back to these extinct armored beasts called "Qilinyu".
The experts made the connection after unearthing a fossil of the creature that measures 30cm long and shows telltale signs of a modern jawbone.
They believe the Qilinyu had armoured bony plates over its jaws that acted as teeth allowing it to slice up prey.
The findings, published in the U.S. journal Science, state that this fish was from a family of creatures (placoderms) that are the first to appear in history with functioning jaws.
"Now we know that one branch of placoderms evolved into modern jawed vertebrates," said study co-leader Zhu Min, a paleontologist at Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology.
The fossil was found in Yunnan, southwest China and contradicts the previous theory that our jaws developed much later in history.
This isn't the first time China has turned up a fishy fossil from millions of years ago.
In 2013, a team of international scientists found a 419-million-year-old fossil at the bottom of a reservoir.
they believe it is the “missing link” in the development of vertebrates, offering more clues to the evolution of humans.
Experts have described the discovery in China as “stunning”.
Palaeontologist Professor John Long of Flinders University, Adelaide, said: “It finally solves an age-old problem about the origin of modern fishes.
“We now know prehistoric fish gave rise to the modern fish fauna as we know it.”
The fossil was shown off by Professor Min Zhu, one of the team of scientists who found it, in his Beijing laboratory.