The discovery of Majungatholus on the island of Madagascar off the southeast coast of Africa cleared up three mysteries that had been puzzling paleontologists for years: 1) What dinosaur left behind numerous fossil teeth on Madagascar? 2) Why were there remains of a Northern Hemisphere pachycephalosaur on the island? 3) How did dinosaurs get from South America to Madagascar?

Paleontologists discovered hundreds of dagger-like fossil teeth throughout Madagascar over a hundred years ago, but no one knew what type of dinosaur had shed the teeth (during a meal, some carnivorous dinosaurs shed a few of their teeth in a manner similar to modern sharks and crocodiles). In 1996, an expedition went to Madagascar to find the dinosaur associated with these teeth. One day, while digging into a hill, a paleontologist found some tail bones. Further digging exposed an upper jaw bone of a large carnivorous dinosaur; the jaw contained the same teeth found scattered throughout Madagascar. The mystery had been solved.

The dinosaur responsible for the fossil teeth was named Majungatholus, a distant relative of Tyrannosaurus rex. It was approximately 20 to 30 feet (6 to 9 meters) long and lived in Madagascar about 70 million years ago. The skull of the dinosaur had a stubby remnant of a horn set between the eyes; some of the skull bones had an unusually rough texture, perhaps echoing patterns in the overlying skin. Paleontologists speculate that the combination of horn and texture on the head may have been used to threaten enemies or attract a mate.