Digging up a fossil does not bring instant enlightenment. Take, for example, a few scraps of bone that turned up in 1975 on the remote Arctic island of Spitsbergen. They were tiny chips covered with dense rows of bumps and dating back 500 million years. If they were scales, they were unlike anything seen before on a vertebrate. Some paleontologists even suggested that they were from the shell of a creature resembling a horseshoe crab. It wasn’t until this past year that compelling proof came: those bone chips belonged to the oldest fish yet found.
Paleontologists from the University of Birmingham in England took a close look at the microstructure of the fossils. They found that while the bone might look bizarre at low magnification, under a scanning electron microscope it had a familiar look. It had the typical combination of tubes and cavities that is unique to dentine--the hard ...
