Another ancient genus of sharks that has extant species is the Heterodontus, which dates back to the Early Toarcian, meaning roughly 180 million years ago. The sharks in this genus are called bullhead ...

The ontogenetic trajectory of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically most basal stem osteichthyan, visualized by synchrotron ...