Its head was ornamented with three horns, a short one above its mouth and two long ones above each eye. Behind these horns was a head frill made of bone and studded with small spikes called ...

“Across a herbivore’s life, its teeth gradually wear down,” said study co-author Professor Paul Barrett. Because of the constant wear and tear, the tooth eventually vanished in some of the ...

Every bite an herbivore takes comes at the expense of ... or swelling in the skin or mouth when touched as in the case of stinging nettle (see ‘Structural defenses' above) or poison ivy ...