Domehead is a term used by the characters in Land Before Time films and television series. It refers to pachycephalosaurs, specifically Pachycephalosaurus and Prenocephale, based on the dome-shaped crests on their heads. In books and credits, three alternate names have been used: crown-head, lizard-head and Bonehead.
Role in the Series
Domeheads appear to be one of the more uncivilized races of the world depicted in the series, with three seen in The Land Before Time attacking Cera in a cave near the Mountains that Burn after Ducky, Petrie and Spike, who she had led into the hazardous area, are left behind without her noticing. They are scared off when a terrifying monster appears; however, the abomination is then revealed to be Littlefoot and the others (who he had rescued) covered in tar and using bones and branches. In The Land Before Time IV: Journey through the Mists, two battling Domeheads, of the same variety as those depicted in the original film, scare a large herd of Egg-Stealers into leaping into a river and, and attempt to attack Littlefoot and his and friends. in the Land of Mists.
However, peaceful Pachycephalosaurus living in harmony with other residents of the Great Valley are seen in in The Land Before Time V: The Mysterious Island and The Land Before Time XII: The Great Day of the Flyers, and even hatchlings in the latter, as in The Land Before Time VI: The Secret of Saurus Rock. Two Great Valley Prenocephale, possibly adolescent, appear in "The Cave of Many Voices" and "The Great Log-Running Game", appearing to be mean to smaller dinosaurs (such as Ducky) but showing cowardice and running when confronted by someone larger (such as Ruby or Cera).
Many theories have been put forward to these contrasting roles. Some scientists think pachycephalosaurs were omnivores and this existing in The Land Before Time may allow them to live in otherwise inhospitable places such as the Mountains That Burn and the Land of Mists; therefore the Domeheads that attacked Cera may have been trying to eat her. A deleted scene in The Land Before Time shows a group of Domeheads (called crown-heads) who are dying of thirst guarding a copse of trees at an oasis from a herd of Gray-noses (Swimmers/Bigmouths) who are dying of starvation and guarding a pond from them. The two species will not share with each other simply due to segregation despite the fact that they will both die in the end. This extreme racism may account for attacking Cera. Also, as pachycephalosaurs are thought to have been territorial animals, territory matters may account for violence in both films.
Finally, it may be simply that the dinosaurs' surroundings influenced their behavior. The dinosaurs in the Great Valley live in a predator-free environment teeming with food and water, where multiple species live together in harmony, so they are more peaceful. The ones living in the caves near the Mountains That Burn, however, dwell in a harsh location where food is scarce and volcanic eruptions occur regularly, as well as struggling to survive constant menace from predators. As a result, they are more aggressive.
Domeheads have been called many different names in the Land Before Time series. The ones that attack Cera in The Land Before Time are called lizard-heads in the books "Friends in Need" and "The Land Before Time: The Illustrated Story", while the ones in the deleted scene are called crown-heads. In the credits for The Land Before Time XI: Invasion of the Tinysauruses, one is called a Bonehead. In the television series however, the only time they are named by characters on screen, they are called Domeheads.