A collection of fossils from the early Silurian Period — from 443.8 million to 419.2 million years ago — unearthed in Southwest China’s Chongqing and Guizhou have provided researchers with clues about the evolution of jawed animals, including humans. Photo: Courtesy of Chinese Academy of Sciences

The tujiaaspis vividus fossil dates back around 436 million years. Photo: Courtesy of CCTV and Chinese Academy of Sciences

A computer generated reconstruction of tujiaaspis vividus. Photo: Courtesy of Chinese Academy of Sciences

A reconstruction of qianodus duplicis. Its tooth spirals indicate that the jawed vertebrate groups which existed during the so-called “Age of Fishes” around 420 to 460 million years ago actually appeared 20 million years earlier than previously thought. Photo: Courtesy of Chinese Academy of Sciences

A reconstruction of fanjingshania renovata. The fish, with bony armor and multiple pairs of fin spines, has been identified as the oldest jawed fish whose anatomy is known. Photo: Courtesy of Chinese Academy of Sciences

A reconstruction of shenacanthus vermiformis. The fishes’ 30 millimeter dorsal fins may show that sharks descended from armored ancestors. Photo: Courtesy of Chinese Academy of Sciences

A reconstruction of xiushanosteus mirabilis. This jawed fish measured 30 millimeters long and had a flat head and trunk armor. Photo: Courtesy of Chinese Academy of Sciences

A fossil with shenacanthus vermiformis and xiushanosteus mirabilis in it. Photo: Courtesy of Chinese Academy of Sciences

Fish fossils unearthed in Chongqing. Photo: Courtesy of Chinese Academy of Sciences

A reconstruction shows fishes of the Silurian Period discovered in Chongqing. Photo: Courtesy of Chinese Academy of Sciences