The oldest ever fish fossil found in Chongqing so far was introduced to the public by Chongqing Municipal Bureau of Planning and Natural Resources on March 3. It can date back 436 million years when Chongqing was still an ocean.
This ancient fish was named "Binhai Yongdong fish" or "Yongdongaspis littoralis." Notably, it is the first creature named at the biological rank of family among all the paleontological fossils discovered in Chongqing. Moreover, the discovery also adds a new advanced biological type to the world's archaic fish.
The oldest ever fish fossil to be found in Chongqing. (Photo provided to iChongqing)
What does a Binhai Yongdong fish look like? What are its life habits? Are there remarkable differences between it with modern fish? Chen Yang, doctoral candidate and senior engineer of the Chongqing Institute of Geology and Mineral Resources, answered these questions.
Jawless fish endemic to East Asia
Though also a kind of fish, Binhai Yongdong fish is remarkably different from modern fish in shape.
"We can describe it as 'bizarre,'" said Chen while raising the fossil in his hands. On the fossil, the most eye-catching part is the "helmet" on the fish head.
The "helmet" looks very similar to the head armor worn by ancient soldiers at first sight, and there are two holes on it: the eye sockets of Binhai Yongdong fish.
Substantial morphological analysis has proven that the archaic fish living in Chongqing 436 million years ago has filled the morphological gap between the two important morphological types of Sinogaleaspis and Eugaleaspiformes and shed more light on how Eugaleaspiformes evolved morphologically.
Binhai Yongdong fish. (Photo provided to iChongqing)
How the fossil of Chongqing's oldest ever fish was found
According to Chen, the fossil of Binhai Yongdong fish was discovered in the 436 million years old early Silurian strata at Yongdong Township, Xiushan Tujia, and Miao Autonomous County in July 2020. More than 10 million years earlier than 423 million years old, Bianchengichthys, the oldest jawed fish fossil found in Chongqing in 2021, is the oldest fish fossil discovered in Chongqing date.
The fossil was being excavated. (Photo provided to iChongqing)
Chongqing's first creature named at the biological rank of family among all the paleontological fossils discovered in the city
As Binhai Yongdong fish occupies an important position in the evolution of early vertebrates, paleontologists have classified it at the biological rank of family, which has been the first time for Chongqing, and also named its new "genus" and "species."
According to Chen, the biological ranks in descending order are kingdom, phylum, class, order, family, genus, and species taxonomically.
In this connection, the fossil of Binhai Yongdong fish found in the marine red beds of Chongqing is expected to provide new evidence of the subdivision and correlation of the Silurian strata in southern China, which is of significant stratigraphical meaning.