The Land Before Time VI: The Secret of Saurus Rock is a 1998 direct-to-video animated adventure musical film and the sixth film in The Land Before Time series about five dinosaurs who live in the Great Valley. It is the first film in which Thomas Dekker is the voice of Littlefoot. This was the second The Land Before Time direct-to-video film to be produced and directed by Charles Grosvenor. Plot One night, Littlefoot's grandfather tells the children stories, the beginning of their world: in the Universe the smoke created the Milky Way Galaxy, and early life on Earth, even a legend about "The Lone Dinosaur", a legendary Longneck (Diplodocus) who protected the Great Valley from the most ferocious Sharptooth (Tyrannosaurus) to ever live. During the fight, the Sharptooth was killed and the Lone Dinosaur suffered a scar across his right eye. Soon after the battle, a huge monolith resembling a sauropod with life-sized Sharptooth teeth arranged around his neck came out of the ground during an earthquake. The dinosaurs called it "Saurus Rock". The legend also states that if anyone damages the monolith, bad luck would descend upon the Valley. The next day, while the children are playing, Littlefoot accidentally falls off a cliff and is saved by a mysterious Diplodocus named Doc. Littlefoot is intrigued by Doc, who is scarred across one eye and displays prior knowledge of the Great Valley's topography. This causes him to assume Doc is the Lone Dinosaur. He tells his friends this, narrating an apparently extemporaneous legend to support his assumption. Inspired, Cera's infant niece and nephew, twins Dinah and Dana, go to Saurus Rock unnoticed. The next day, a worried Cera informs Littlefoot that Dinah and Dana are missing, and the group deduces where they are headed. When Littlefoot and his friends finally reach Saurus Rock, they see Dinah and Dana on the top. As they climb up to rescue them, Dinah and Dana fall off the top and land on one of the stone teeth on the monolith that Cera is on, and it suddenly breaks off and crumbles upon landing on the ground nearly hitting Spike. Dinah and Dana start to cry. But Cera tells Dinah and Dana that it is not their fault that Saurus Rock was broken; but Littlefoot's since if he had not been talking about it and Doc, then Dinah and Dana would not have run away