A study said palaeontologists showed an ancient herbivore reptile, Priosphenodon, evolved special type of tooth enamel, similar to that of mammals, with high resistance to wear and tear. Its enamel crystals are "woven" into long threads called enamel prisms, which are "almost exclusively" found in mammals. Spiny-tailed Australian lizard has prismatic enamel like Priosphenodon today, study said.