| "You are a Spiketail, so we will call you 'Spike'."
The subject(s) detailed in this article has/have been given a conjectural (and, as a result, unofficial) name, due to the lack of an official name for the article subject(s) to be referred to by.
The Sailback Sharptooth is a Spinosaurus who appears in The Land Before Time XII: The Great Day of the Flyers as the sole antagonist of the film. He has no voice actor in the film, instead the sounds are composed of crocodile snarls from the real animal, among others.
A sleep-flying Guido flies into the Mysterious Beyond. He falls on something and wakes up. Upon waking up and looking around, he thinks the others were playing a trick on him. He says they succeeded, at the same time laughing nervously, and the ground shakes below him. He thinks it's an earthshake (earthquake), only for it to be revealed that he is standing on top of a sleeping sharptooth that wakes up and roars. Guido, who had previously said that an earthshake is the scariest thing from a nightmare, takes it back and screams, before falling off the sharptooth. The sharptooth sees him and roars, and Guido gets up and tries to run, but is immediately snapped up in the sharptooth's jaws.
The Sharptooth starts walking when he stops, his eyes widen, and he starts growling before chuckling and then laughing, opening his mouth to reveal Guido tickling its mouth with his feather. The sharptooth's mouth opens wide, and Guido jumps out and lands on the ground. The sharptooth stops laughing and licks the spot that Guido tickled, before coughing out several of Guido's feathers. Guido is disgusted, but his disgust turns to fear when the sharptooth stares down at him and chases after him.
The sharptooth quickly catches up to him, but Petrie soars in and grabs Guido just as the sharptooth snaps his jaws shut. The sharptooth continues chasing them, snapping his jaws shut several times in an attempt to bite them, but misses. The two then fly in the opposite direction, and the sharptooth stops for a moment before chasing them again. Petrie starts getting tired as he flies while carrying Guido.
Littlefoot, Cera, Ducky, and Spike come and see the sharptooth, and try to figure out a way to distract it. Spike then slides into the others by accident and they tumble down the hill. It is then Petrie and Guido notice the sharptooth has stopped following them. Instead, the sharptooth turns its attention to the others, and chases after them. Petrie and Guido fly after it, and step on his head, only for the sharptooth to snap at them before continuing the chase.
Littlefoot then spots two giant rocks with the top of both of them touching each other, looking slightly like a bridge, and, coming up with a plan, Littlefoot tells the group to run through it. Petrie and Guido barely make it through, and the sharptooth was so focused on getting them that he runs through the two rocks and his spine gets stuck between them, just as Littlefoot planned. The group then run off as the sharptooth tries to free himself.
- This is the second sharptooth to appear in the franchise that is ticklish. The first sharptooth was the blue Deinonychus from The Land Before Time XI: Invasion of the Tinysauruses.
- This Spinosaurus has yellow sclera just like the Swimming Sharptooth the Liopleurodon from The Land Before Time IX: Journey to Big Water.
- The Sail-Backed Sharptooth is the first spinosaurid to appear in the franchise.
- The Sailback Sharptooth's defeat, which involves him getting trapped by rocks while chasing the kids, could be a small reference to the Spinosaurus from Jurassic Park III getting trapped by trees in its first pursuit of the humans.
- Location of Sailback Sharptooth is later re-used in Nightmare Longneck in Chomper's Nightmare from TV series.
- This Sailback Sharptooth is bit similar to Rudy from Ice Age: Dawn of the Dinosaurs. Both are Spinosaurid theropod antagonists and both of them survived.
- unlike the real spinosaurus he is shown with 2 fingers like a trex instead of 3 fingers
Land Before Time Wiki has a collection of images and media related to Sailback Sharptooth (The Great Day of the Flyers).
- Littlefoot calls the Sharptooth a 'he'.