CT scans of the fossilized skull of Dwykaselachus oosthuizeni — a shark-like fish that lived during the Permian period, around 280 million years ago — reveal the origin of chimaeras, a group of cartilaginous fish related to sharks. The research appears today in the journal Nature.
Chimaeras, or chimaeroid fishes (subclass Holocephali), include 47 living species, known in various parts of the world as ratfish, rabbit fish, ghost sharks, St. Joseph sharks or elephant sharks.
They represent one of four fundamental divisions of modern gnathostomes (jawed vertebrates).
With large eyes and tooth plates adapted for grinding prey, these deep-water dwelling fish are far from the killer sharks of Hollywood. Their anatomy comprises features reminiscent of sharks, ray-finned fishes and…