An international team of scientists in China has discovered what may be the earliest known creature with a distinct face, a 419 million-year-old fish that could be a missing link in the development of vertebrates.
The fossil find in China’s Xiaoxiang Reservoir, reported by the journal Nature on Thursday, is the most primitive vertebrate discovered with a modern jaw, including a dentary bone found in humans.
This “finally solves an age-old problem about the origin of modern fishes,” said John Long, a professor in palaeontology at Flinders University in Adelaide.
Scientists were surprised to find that the heavily armoured fish, Entelognathus primordialis, a previously unknown member of the now extinct placoderm family, had a complex small skull and jaw bones.
That appeared to disprove earlier theories that modern vertebrates with bony skeletons, called osteichthyes, had evolved from a shark-like creature with a frame made of cartilage.
Instead, the new find provides a missing branch on the evolutionary tree, predating that shark-like creature and showing that a bony skeleton was the prototype for both bony and cartilaginous vertebrates.