Which dinosaur has two heads?

Not, as you might suspect, the biggest dinosaur. The giant sauropods had heads only about as big as those of horses. Though they ate prodigiously, they didn't need big chewing muscles because the real work of masticating food was done in their gizzards.

Counting bony projections, the biggest head belongs to Triceratops horridus, a comparatively compact, elephant-sized dinosaur.