Evolution of the Skeleton

Since Darwin’s time scientists have been studying a type of fish that lived 400 million years ago called Heterostracans. These fish were covered in a tough exoskeleton, but scientists couldn’t decide exactly where it came from. Was it a precursor to bone? To teeth? New research is suggesting all those old theories may be as dead and buried as the fish fossils, and this exoskeleton is just another way of making bone. Adam Murphy spoke to Joseph Keating of the University of Manchester to learn more