The Land Before Time XI: Invasion of the Tinysauruses is a 2005 direct-to-video animated film and the 11th film in The Land Before Time series. It was released on January 11, 2005.
As the film begins, Littlefoot and his friends Ducky, Petrie and Spike are eagerly waiting to nibble the first tree sweets. Ducky is about to take one, but Littlefoot quickly tells her to stop and reminds them all that none may take any tree sweets until "Nibbling Day". This however, doesn't stop Petrie from flying to the tree's crown and trying to take one. Just then, Cera's father emerges and states very clearly how every dinosaur in the Great Valley has waited a long time to taste the tree sweets. As Cera, too, appears before them, she reminds them that she is the one who is supposed to get the first tree sweet because she was the one who found the tree sweet tree in the first place, although it was indeed Littlefoot who did it. Cera also teases Littlefoot for being too little to actually reach the tree sweets.
Meanwhile, Cera's father is visited by an old friend, a female threehorn named Tria, who he used to have a crush on and still does right now. She also reveals his name to be Topsy (although it may simply be a nickname).
After speaking a while with her, he promises Tria that she will get the first tree sweet of the season; which Cera, who appears just in time to hear him say this, becomes very upset about. From that moment on, Cera refuses to make friend with Tria and simply shrugs her off whenever she tries to talk to her.
Littlefoot, meanwhile, goes off by himself, feeling very down about how little he is. As he returns to the tree sweet tree, he climbs up the cliff right next to it and tries to reach the tree sweets by himself. As he does, he accidentally falls right through the tree and knocks down every single tree sweet. Realizing the trouble he is now in, he faints. As he wakes up, he finds himself surrounded by several miniature longnecks (called Tinysauruses). As the one named Skitter eats a tree sweet off the top of his nose, Littlefoot screams in fear, sending the longnecks scattering, but drawing the attention of Topsy and Tria.
Upon noticing that every tree sweet is gone, all the dinosaurs in the valley are standing in front of the tree; many of them, including Topsy, suspecting Littlefoot to be the guilty party. Littlefoot, afraid to admit it was his fault that the tree sweets fell off the tree, blames everything on the tiny longnecks. He is believed, and everyone starts looking for the tiny longnecks, preparing to drive them out of the Great Valley once they have been found. However, the grown-ups prove to be fortunately incompetent at searching, as shown by a longneck chasing her own tail round a tree and a threehorn getting stuck under a root. As Littlefoot and Cera are searching the valley, Littlefoot falls down a hole in the ground where he encounters one of the Tinysauruses named Skitter; the very same one Littlefoot spotted eating a tree sweet off of his nose. First being afraid of them, Littlefoot flees deeper into the cave; but soon enough, he finds that they are actually friendly creatures, who admire him for his size. He befriends them all, and meets their leader, Big Daddy, who at first believes that Littlefoot told the bigger dinosaurs about them, but becomes more accepting of Littlefoot after he learns that he discovered their cave by accident, and has not told anyone. Upon hearing how difficult it is for the Tinysauruses to find food, he promises to bring them as much food as he can every night.
One night, Cera catches Littlefoot gathering food so she decides to check it out. She wakes up Ducky, Spike, and Petrie and they go see what Littlefoot's up to. They fall down the hole like Littlefoot did. They all get to see the tiny longnecks for themselves, and promise not to tell the adults. Even Cera, who is still angry with her father, promises to keep it secret, mainly because she finds out that she can relate to Lizzie, who feels that Big Daddy is too bossy, in a similar manner to Topsy. Big Daddy is accepting of the children, but is skeptical about befriending the bigger dinosaurs, believing that because they are bigger, they believe themselves to be more important.
When sneaking off to see the Tinysauruses again, Littlefoot and his friends are confronted by Topsy. But when he tries to ask them why they are out so late at night, Cera angrily throws the question back at him. Topsy manages to see them off. Just as Tria comes up to see him, they spot two of the tiny longnecks, Skitter and Lizzie, who have journeyed to the world above to find out why Littlefoot and the others have not come back yet. A chase ensues which eventually reveals their hideout. As the grown-ups prepare to block the caverns; Littlefoot, realizing that he must tell the truth, admits that while the Tinysauruses did eat all the tree sweets, they would not have been able to if he had not knocked them all off the tree in the first place. The grown-ups leave, deciding not to block the entrance, but a sudden rockslide seals the hideout anyway.
Upon hearing that he had initially blamed everything on the Tinysauruses, Littlefoot's friends don't even want to talk to him because of what he has done. Littlefoot, angry at his friends' rejection of him, leaves them and decides to set things right on his own.
Meanwhile, Cera apologizes to Tria after having seen how her father treated the Tinysauruses like pests, and the two become friends. Meanwhile, the Tinysauruses, led by Big Daddy, are making their way through the caves to leave the Great Valley for good, heading to the Mysterious Beyond, where they believe they may be safe from bigger dinosaurs tormenting them. However, they are proven wrong as they are chased back through the caves and into the Great Valley by a pair of Utahraptor. The Tinysauruses return and through sheer weight and number, the allied force of the Great Valley dinosaurs and the Tinysauruses drive the Utahraptor out of the valley for good.
The following Nibbling Day, everyone gathers at the now replenished tree sweet tree to celebrate. Littlefoot is given the chance to retrieve the first tree sweet and is delighted to find he can finally reach the them. Grandpa Longneck remarks that he grew taller the moment he stood up for the Tinysauruses. The dinosaurs, small and large alike, join together to enjoy everything the tree has to offer together, learning that even the smallest creatures can make a big difference.
After the film fades to black, a tree sweet falls past the screen, which is promptly snatched out of the air by Petrie, who grins at the camera and flies off.
- Aaron Spann as Littlefoot
- Jeff Bennett as Petrie
- Aria Noelle Curzon as Ducky
- Michael Clarke Duncan as Big Daddy
- Miriam Flynn as Grandma Longneck
- Nika Futterman as Rocky
- John Ingle as the Narrator/Topsy
- Leigh Kelly as Skitter
- Tress MacNeille as Mama Swimmer/Mama Flyer
- Camryn Manheim as Tria
- Kenneth Mars as Grandpa Longneck
- Anndi McAfee as Cera/Longneck
- Ashley Rose Orr as Dusty
- Rob Paulsen as Spike/Kosh
- Cree Summer as Lizzie/Bonehead
- It is paired with Shark Tale.
- This was the first Land Before Time film to be released in a different month rather than December since the original The Land Before Time (which was released in November); all of the previous sequels were released in December.
- This is the first appearance of Tria.
- This is the only appearance of Big Daddy and the Tinysauruses, though they make a cameo in The Land Before Time XII: The Great Day of the Flyers.
- This is the only film, besides film VI, where the gang doesn't leave the Great Valley.
- This is the only film that Aaron Spann is the voice for Littlefoot.
- This is the last Land Before Time film to use the Universal Cartoon Studios logo; the last film overall to use the logo was The Adventures of Brer Rabbit.
- This is the last film in which Tress MacNeille voiced Mama Swimmer, as the character had no speaking roles in the twelfth or thirteenth films, and MacNeille left the series prior to the fourteenth film.
- This was the last Land Before Time film to be released on VHS.
- The characters never use the term "Tinysauruses," referring to them only as "tiny longnecks." However, Ducky calls them Tinysauruses in the TV episode Stranger From the Mysterious Above.
- The theme played during the raptor chase was from The Land Before Time VII: The Stone of Cold Fire as was like the theme of Pterano and his henchmen.
- This is the second film in which Spike and Petrie are shown crying (the first was The Land Before Time VII: The Stone of Cold Fire).
- This is the fifth film in which Ducky cries.
- The black background, Petrie is in is similar to a post-credits scene, except it is a pre-credits scene.
- In the ending, the Ankylosaurus, Stegosaurus, Grandma and Grandpa Longneck and others are rendered in CGI.
- This is the fourth film where Sharpteeth have gotten into the Great Valley. The first three being The Land Before Time II: The Great Valley Adventure , The Land Before Time VI: The Secret of Saurus Rock and The Land Before Time IX: Journey to Big Water.
- This film marks the last time Michael Tavera's rearrangements of James Horner's original themes from the first film (uncredited in this film) would be heard in a Land Before Time film (one theme was heard in the scene where Ducky, Petrie, and Spike tell Littlefoot why they are mad at him and the other theme was heard in a brief scene where the Sharpteeth come out of a cave), as Horner died in a plane crash over 10 years later on June 22, 2015.
- This is the last Land Before Time film to be produced in full screen. The next films starting with The Land Before Time XII: The Great Day of the Flyers would start being produced in widescreen.