The three-horned dinosaur Triceratops is one of the most widely known exhibits in the Senckenberg Nature Museum in Frankfurt. Triceratops was a plant eater that could reach a length of up to nine meters. It occurred in present-day North America. The horns and the large neck plate (or frill) likely served as defensive structures. The skull was connected to the neck vertebrae by means of a ball-and-socket joint. This rendered the head highly mobile and the horns could strike out in all directions.