Deinocheirus

Deinocheirus was a big, long-armed dinosaur that roamed Mongolia about 70 million years ago. For decades, scientists only knew it from a pair of enormous fossilized arms, earning it the name 'horrible hand'. Later discoveries revealed its full, unusual body shape, solving a long-standing dinosaur mystery.

• Its name means 'horrible hand' in Greek, referencing its large clawed arms.
• First discovered in 1965, but complete skeletons weren't found until 2014.
• Some fossil specimens were illegally taken from Mongolia but later returned.