Ancient fish had synovial joints, challenging the idea that flexible skeletons evolved on land. Fossils and modern fish show ...

Jawed vertebrates known as gnathostomes appear to be the first creatures with the synovial joints, according to Shubin. These joint cavities can be seen in cartilaginous fish such as skates or sharks.

Analysis revealed cavitated joints in the cartilaginous fish, but not in lampreys. Additionally, the cartilaginous fish exhibited certain proteins and developmental processes that are shared with ...