Acanthodes and shark-like conditions in the last common ancestor of modern gnathostomes

New analysis of an Acanthodes braincase forces a reappraisal of the phylogeny of gnathosomes, suggesting that the vertebrate head underwent reorganization not only before the emergence of jaws, but also afterwards. The acanthodians, a long-extinct group of fish that thrived during the Palaeozoic era, more than 420 million years ago, are central to our understanding of the origin of modern gnathostomes, the jawed vertebrates. Most acanthodians...