BEIJING, Sept. 25 (UPI) -- A 429-million-year-old fish fossil in China with a modern type of jaw may be the earliest known creature with a recognizable face, researchers said.
This fish from China is a placoderm, a member of an extinct group of gnathostomes (jawed vertebrates), but its jaw is more like that of a modern bony fish and its discovery could offer a new view on early evolution of the creatures, research by Chinese and British researchers released Wednesday indicated.
Jaw evolution is one of the key episodes in the advancement of vertebrates, the researchers said, but the gap between jawed and jawless vertebrates is so wide, it is hard to distinguish individual evolutionary steps in the transition.
Min Zhu of the Chinese Academy of Sciences in Beijing and his colleagues studied a step near the end of the process, where modern jawed vertebrates -- such as sharks and bony fishes -- emerge from a collection of jawed, armored fishes known as placoderms.
The new fossil sucker-punched the thought the most recent common ancestor of jawed vertebrates resembled modern sharks, co-researchers Matt Friedman and Martin Brazeau said. They said the finding suggests strong evidence for the evolutionary link between placoderms and osteichthyans (bony fish), and forces rethinking of early gnathostome evolution.
The findings were published in the latest edition of Nature.