Fossils in China reveal rise of jawed vertebrates

A trove of fossils in China unearthed in rocks dating back some 440 million years showed new fish species and provided concrete evidence of the origin and earliest evolution of the jawed vertebrates.

The four papers published Wednesday in the journal Nature described an array of findings based on the fossils found at two fossil beds in the early Silurian strata -- "Chongqing Fossil Bed" and "Guizhou Shiqian Fossil Bed."

Silurian is an era about 440 to 410 million years ago, during which the jawed vertebrates evolved. It was a breakthrough in life evolution, but it lacks previous paleontological records.

The researchers, led by Zhu Min from the Institute of Vertebrate Palaeontology and Palaeoanthropology under the Chinese Academy of Sciences, provided the earliest direct evidence for the evolution of jawed vertebrates.

They described a new genus and species of an early Silurian jawed fish based on isolated tooth whorls collected in southwest China's Guizhou Province, extending the record of the teeth by 14 million years. It might be the oldest known teeth from any jawed vertebrate.

Zhu's team also found in Chongqing the fossils of the well-preserved jawed fishes with complete bodies, which exhibited extensive chest armor plates and offered more clues to the shark's evolution.

In another paper, the researchers reported a jawless freshwater fish that possessed a pair of fin folds, considered a massive innovation that evolved in the jawed vertebrate lineage after divergence from living jawless vertebrates.

The pair are believed to be the predecessor of paired fins that eventually gave rise to our limbs.

"The two fossil beds, for the first time, allow a close inspection of the shape and life of Silurian fishes," said Zhu. "These discoveries shed light on the rise of jawed vertebrates."