In 1985, Argentinian palaeontologist Jose Bonaparte announced news of a big, bizarre dinosaur unlike anything described before. Carnotaurus ('carnivorous bull") had a deeper, shorter, more bull-like head than other theropods.

Most extraordinary were the pointed horns above its eyes - perhaps butting weapons used by fighting rivals. Other remarkable features included small, forward-facing eyes, spinal bones with wing-like projections, very short arms, and prominent rows of scales along the back and sides.