Washington DC, May 25 -- New research from the University of Chicago shows that dentine, the inner layer of teeth that transmits sensory information to nerves inside the pulp, first evolved as sensory tissue in the armoured exoskeletons of ancient fish.

Paleontologists have long believed that teeth evolved from the bumpy structures on this armour, but their purpose wasn't clear.

The new study, published this week in Nature, confirms that these structures in an early vertebrate fish from the Ordovician period, about 465 million years ago, contained dentine and likely helped the creature sense conditions in the water around it.

The research also showed that structures considered to be teeth in fossils from the Cambrian period (485-540 mi...