![](http://www.ecns.cn/hd/2022/07/08/36fadfb05e924960a5c872a953c43f73.jpg)
A researcher shows the yunnanozoan fossils dating back 518 million years in Nanjing, east China's Jiangsu Province, July 8, 2022. (Photo: China News Service/Yang Bo)
Cartilaginous features found in their fossilized remains are comparable to modern vertebrates, paleontologists have discovered. The evolution of an internal skeleton marks a milestone in the history of life on Earth. The research was published on Science on Friday.
![](http://www.ecns.cn/hd/2022/07/08/d2bf63897c284100a626b961c6c691de.jpg)
Photo shows the yunnanozoan fossils dating back 518 million years in Nanjing, east China's Jiangsu Province, July 8, 2022. (Photo: China News Service/Yang Bo)
![](http://www.ecns.cn/hd/2022/07/08/13cb5aeaee114d369573d78e213e6b20.jpg)
Photo shows the yunnanozoan fossils dating back 518 million years in Nanjing, east China's Jiangsu Province, July 8, 2022. (Photo: China News Service/Yang Bo)
![](http://www.ecns.cn/hd/2022/07/08/f7765be6efda47ab9a4fc0431ec47ddf.jpg)
A researcher shows the yunnanozoan fossils dating back 518 million years in Nanjing, east China's Jiangsu Province, July 8, 2022. (Photo: China News Service/Yang Bo)