The Pachycephalosaur Pack are antagonists in The Land Before Time.
These are called Domeheads in the LBT movies and series. There are no main characters which are of this type, but they have been seen in the background or as minor speaking roles from the first movie onward including the TV series.
The Pachycephalosaurus was first seen in the Land Before Time when a herd attacked Cera, they were then scared off by Littlefoot & friends. Unlike in subsequent appearances, Pachycephalosaurus in the first film are portrayed with short horns on their noses (some have onewhile others have two; this may indicate male and female).
Another one was later seen in The Land Before Time IV: Journey Through the Mists where it attacks Littlefoot & his friends. The dome-headed dinosaur then fights another Pachycephalosaurus for territory.
The Pachycephalosaurus was given an important role in The Land Before Time XI: Invasion of the Tinysauruses, helping the Valley in search of the Tiny Longnecks after the leaves from sweet treat tree were eaten (as in blame of Littlefoot), one even joined in singing the song "Creepy Crawlies".
Pachycephalosaurus also can be found in the Great Valley; Pachycephalosaurus was in a meeting with the other dinosaurs in the fifth film.
Pachycephalosaurus like most dinosaurs in The Land Before Time have plain and simple color scheme. Depending on gender males come in two variations of purple while females come in a brownish or light purple color. In exception to these colors, hatchlings have a greenish color, with a lighter green underbelly.
Pachycephalosaurus belongs to a group of dinosaurs called Pachycephalosaurids which came from Pachycephalosaurus in general. It is a bipedal herbivore with an extremely thick skull roof, long legs and short arms. It lived during the Late Cretaceous lived with other North American dinosaurs such as Triceratops and Tyrannosaurus. The fossil can be found in both the United States and Canada.
The thick skull domes of Pachycephalosaurus and related genera gave rise to the theory that pachycephalosaurs used their skulls to fight each other. This theory has been disputed in the past few years. The pack only appears briefly in The Land Before Time, to terrorize the protagonistic character Cera. They are highly aggressive towards the young Triceratops, and her killing is only avoided once Ceras friends (disguised as a tar monster come into the caves.
They flee, and do not return for the rest of the film. It is unknown as to why the domeheads in the pack attack young Cera. Some have justified it through the fact the pack is simply territorial, while others have suggested that their attack was provoked by hunger. Domehead is a term used by the characters in Land Before Time films and television series. It refers to pachycephalosaurs, specifically [http://landbeforetime.wikia.com/wiki/Pachycephalosaurus 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 in LBT, 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 scare a large herd of Egg-Stealers in to leaping into a river and one of them nearly attacked Littlefoot and friends. in the Land of Mists.
However, peaceful Pachycephalosaurus living in harmony with other residents of the Great Valley are seen 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 ValleyPrenocephale, possibly teenage, 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.
These herbivores have a thick domed skull, which is used for ramming eachother on the flanks during fights between males and as defence. They are peacful herbivores most of the time, but not when they are disturbed. They [75-65]in Mongolia and were two metres long. Two appear in The Land Before Time (TV Series) in The Cave of Many Voices and The Great Log-Running Game. In "The Cave of Many Voices" they steal some tree stars from Ducky but abandon them when Ruby chases them away.First, the skull roof could not have adequately sustained impact associated with such shock. Also, there is no evidence of scars or other harm on fossils of Pachycephalosaurus skulls.  Furthermore, the dorsal vertebrae show that the neck was carried in an "S"- or "U"-shaped curve, not a straight direction, and thus to weak for direct clash of heads. Lastly, the rounded shape of the skull would lessen the contacted surface area during head-butting, resulting in misses.
It is more likely that the Pachycephalosaurus and other pachycephalosaurs hit each other in the flanks. In this setting, an individual may have stood parallel or faced a rival directly, using intimidation displays to rival. If intimidation failed, the Pachycephalosaurus would bend its head down and to the side, and strike the rival pachycephalosaur on its flank. This hypothesis is back up by the broad width of most pachycephalosaurs, a trait that would have kept vital organs from harm. The flank-butting theory was first proposed by Sues in 1978, and expanded by Ken Carpenter in 1997.
Scientists do not yet know what these dinosaurs ate. Having small, ridged teeth they could not have chewed tough, fibrous plants as effectively as other dinosaurs of the same time. It is assumed that pachycephalosaurs lived on a mixed diet of leaves, seeds, fruit and insects. The sharp, jagged teeth would have been very effective for shredding plants. The thick skull domes of Pachycephalosaurus and related genera gave rise to the theory that pachycephalosaurs used their skulls to fight each other.
This theory has been disputed in the previous few years.
- Real Pachycephalosaurus were herbivores.