Five early Silurian fishes from China rewrite the evolutionary story of “from fish to human”

Scientists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences (CAS) recently discovered two fossil repositories in the early Silurian strata in Southwest China’s Chongqing Municipality and Guizhou Province that are rewriting the evolutionary story of “from fish to human”.

Their findings were published in Nature on September 28 in four articles in the same issue.

Among the extant vertebrates, 99.8 percent of species, including humans, are gnathostomes or jawed vertebrates. The basic body plan and several key organs of humans can be traced back to the origin of gnathostomes. The rise of jaws is one of the biggest innovations in the history of vertebrates. However, how this innovation happened remains hidden in mist, mainly because the discovered fossils of early jawed vertebrates in large numbers were dated only from the beginning of the Devonian (419 million years ago), while molecular data prove that the origin of jawed vertebrates should be as early as 450 million years ago. Hence, there is a huge gap in the fossil record of the early jawed vertebrates, spanning at least 30 million years from the Late Ordovician through most of the Silurian.

The latest findings of Zhu Min’s team from CAS’s IVPP were unearthed from two new fossil depositories, shedding light on the rise of jawed vertebrates. These jawed fishes were already thriving in the waters of the South China block, at least 440 million years ago, and by the late Silurian, more diverse and larger jawed fishes had evolved and begun to spread around the world, opening the saga of fish landing and human evolution.

Discoveries of fish fossils from the two depositories help to trace many human body structures back to ancient fishes, some 440 million years ago, and fill some key gaps in the evolution “from fish to human”, providing further strong evidence of the evolutionary path.

“It’s really an awesome, game changing set of fossil discoveries. It rewrites almost everything we know about the early history of jawed animal evolution,” said John Long from Flinders University, Australia, Past President of the Society of Vertebrate Paleontology.

The Chongqing fish fossil depository in the Upper Red Beds of the Silurian system dates back to 436 million years ago. It is the world’s only early Silurian Lagerst？tte (a fossil depository with exceptional preservation) with complete, head-to-tail jawed fishes, and provides a peerless chance to peek into the proliferating “dawn of fishes”. This fossil “treasure hoard” stands among other great Chinese Lagerst？tten: the Chengjiang Biota and the Jehol Biota; all provide key solutions to jigsaw puzzles in the tree of life.

Five early Silurian fishes from China rewrite the evolutionary story of “from fish to human” [IMAGE: SCIENCEAPE]

Source: Institute of Vertebrate Paleontology and Paleoanthropology (IVPP),

Chinese Academy of Sciences