Silurian remains rewrite evolutionary history ‘from fish to human’

Sep. 28 () –

Two fossil deposits discovered in the earliest Silurian strata in southwestern Chongqing and Guizhou, China, are rewriting the evolutionary history of “from fish to human”.

So consider scientists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences, who publish their findings in four papers published in Nature.

Among extant vertebrates, 99.8% of species, including humans, are gnathostomes or jawed vertebrates. The basic body plan and several key organs of the human being date back to the origin of the gnathostomes. The lifting of the jaws is one of the greatest innovations in the history of vertebrates.

However, how this innovation happened remains shrouded in mist, mainly because fossils of early jawed vertebrates were only found in large numbers until the beginning of the Devonian (419 million years ago), while molecular data prove that the origin of jawed vertebrates should be earlier than about 450 million years.

Thus, there is a large gap in the fossil record of the earliest jawed vertebrates, spanning at least 30 million years from the Upper Ordovician to most of the Silurian.

The latest findings from IVPP’s ZHU Min team unearth two new fossil deposits, shedding light on the rise of jawed vertebrates: These jawed fish already thrived in the waters of the South China Block, at least 440 years ago. million years ago, and by the more diverse and larger-jawed Late Silurian Fishes that began to spread throughout the world, opening the saga of the landing of fish on the mainland and that gave rise to the evolution to the human being.

Discoveries of fish fossils from the two deposits help trace many structures of the human body back to ancient fish, some 440 million years ago, and they fill in some key gaps in the evolution of “from fish to human”.

“It’s really an amazing and revolutionary set of fossil discoveries. It rewrites almost everything we know about the early evolutionary history of jawed animals,” he said. it’s a statement John Long of Flinders University, Australia, former president of the Society for Vertebrate Palaeontology.

The Chongqing fish fossil deposit in the Upper Red Beds of the Silurian system dates to 436 million years ago. It is the world’s only Early Silurian Lagerstätte (exceptionally preserved fossil deposit) that preserves fish with complete jaws, from head to tail, providing an unparalleled opportunity to catch a glimpse of the proliferating “dawn of the fishes”. This fossil “treasure treasure” is among other great Chinese Lagerstätten: Chengjiang Biota and Jehol Biota, all providing key puzzles previously missing from the tree of life.