The discovery of a fossil “treasure hoard” illuminates the rise of fishes.
Researchers from the Chinese Academy of Sciences‘ Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) have recently found two fossil repositories in the early Silurian strata of southwest Guizhou and Chongqing that are rewriting the “from fish to human” evolutionary story.
Four different papers describing their findings were recently published in the journal Nature.
Humans are one of the 99.8% of species of extant vertebrates that are gnathostomes, or jawed vertebrates. The basic body plan and several key organs of humans can be traced back to the origin of gnathostomes. One of the most significant developments in the evolution of vertebrates is the emergence of jaws.
The Chongqing fish fossil depository is the world’s only early Silurian Lagerstätte which preserves complete, head-to-tail jawed fishes, providing a peerless chance to peek into the proliferating “dawn of fishes.” Credit: NICE Tech/ScienceApe
However, how this innovation occurred remains a mystery, owing to the fact that fossils of early jawed vertebrates were not discovered in large numbers until the beginning of the Devonian (419 million years ago), despite molecular data indicating that the origin of jawed vertebrates should have occurred earlier than 450 million years ago. As a result, there is a significant gap in the fossil record of early jawed vertebrates, lasting at least 30 million years from the Late Ordovician to the Silurian.
The latest findings of Zhu Min’s team from IVPP are 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 late Silurian, more diverse and larger jawed fishes had evolved and began to spread around the world, opening the saga of fish landing and our humans eventually evolved.
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 of “from fish to human,” and provide further iron evidence to the evolutionary path.
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 Lagerstätte (fossil depository with exceptional preservation) which preserves complete, head-to-tail jawed fishes, providing a peerless chance to peek into the proliferating “dawn of fishes”. This fossil “treasure hoard” stands among other great Chinese Lagerstätten: Chengjiang Biota and the Jehol Biota, all provide key jigsaw puzzles previously missing in the tree of life.
References: “The oldest gnathostome teeth” by Plamen S. Andreev, Ivan J. Sansom, Qiang Li, Wenjin Zhao, Jianhua Wang, Chun-Chieh Wang, Lijian Peng, Liantao Jia, Tuo Qiao and Min Zhu, 28 September 2022, Nature.
“Galeaspid anatomy and the origin of vertebrate paired appendages” by Zhikun Gai, Qiang Li, Humberto G. Ferrón, Joseph N. Keating, Junqing Wang, Philip C. J. Donoghue and Min Zhu, 28 September 2022, Nature.
“Spiny chondrichthyan from the lower Silurian of South China” by Plamen S. Andreev, Ivan J. Sansom, Qiang Li, Wenjin Zhao, Jianhua Wang, Chun-Chieh Wang, Lijian Peng, Liantao Jia, Tuo Qiao and Min Zhu, 28 September 2022, Nature.
“The oldest complete jawed vertebrates from the early Silurian of China” by You-an Zhu, Qiang Li, Jing Lu, Yang Chen, Jianhua Wang, Zhikun Gai, Wenjin Zhao, Guangbiao Wei, Yilun Yu, Per E. Ahlberg and Min Zhu, 28 September 2022, Nature.
The study was funded by the Chinese Academy of Sciences.