The films follow a friendship of a group of young ornithodirans by the names of Littlefoot (Apatosaurus), Cera (Triceratops), Ducky (Saurolophus), Petrie (Pteranodon), and Spike (Stegosaurus).
During the age of the dinosaurs, a massive famine forces several herds of dinosaurs to seek an oasis known as the Great Valley. Among these, a mother in a diminished "Longneck" herd gives birth to a single baby, named Littlefoot. Years later, Littlefoot plays with Cera, a "Three-horn", until her father intervenes, whereupon Littlefoot's mother describes the different kinds of dinosaurs: "Three-horns", "Spiketails", "Swimmers", and "Flyers". That night, as Littlefoot follows a "Hopper", he encounters Cera again, and they play together briefly until a large "Sharptooth" attacks them. Littlefoot's mother comes to their rescue, but receives fatal injuries in the process. An earthquake swallows up the Sharptooth and divides Littlefoot and Cera from their herds. Littlefoot receives advice from his dying mother before she passes away. Confused and in grief, Littlefoot meets an old "Clubtail" named Rooter, who consoles him. He is then guided by his mother's voice telling him to follow the sun to the Great Valley.
Shortly after the events of The Land Before Time, List of The Land Before Time characters#Littlefoot and his four friends (now teenagers) are living happily in their new home in the Great Valley, under their families' watchful eyes. One day, the gang attempts to get to the sheltering grass to play, but land in the tar pit surrounding it. The adults rescue them and subsequently chastise them for crossing the sinking sand. During the next night, the children have a secret meeting and decide that they need to prove they are mature by running away for a while into the Mysterious Beyond, a location just outside the Valley.
One day, a shower of meteorite impacts near the Great Valley and causes a rock slide in the Mysterious Beyond, which blocks the water supply of the Great Valley. The increasing lack of water causes conflicts between the inhabitants of the Great Valley, who have lived in relative peace and harmony until this event.
When Littlefoot grandfather falls ill, The dinosaurs only way to cure him is a flower in the forbidding land of mist which hold unexpecting perils and danger.
One day, a swarm of "locust" descends upon the Great Valley, devouring all plants and reducing it to a barren wasteland. The inhabitants of the Great Valley have no choice but to find another place where they can survive until the plants have grown back. However, the leaf-gobblers have left a path of devastation behind them, leaving no food for the dinosaurs to find. After searching for many days, tension enters the group as Cera's father and Littlefoot's grandfather argue over changing their course, beginning a fight between Littlefoot and Cera. The fight immediately breaks up when Cera's father announces that every herd should go its own way the next morning. Not wanting to be separated, Littlefoot leads his friends off in the night, in the hope they can find food before they are caught. They leave a trail for the grownups to follow, and eventually reach the "ocean". Disheartened by the undrinkable water, the children spy a verdant island connected to the mainland by a thin land bridge. On their way, an earthquake occurs, which creates a tsunami from which they narrowly escape. They quickly tuck in to the plentiful bounty of the island, but are then horrified to discover the tsunami has destroyed the land bridge.
One night, Littlefoot's grandfather tells the children a legend about "The Lone Dinosaur", a legendary Longneck who protected the Great Valley from the most ferocious Sharptooth 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.
One evening, Petrie begins telling a tale of the best creatures of the world, the Flyers, but it is met with disapproval from Cera. Meanwhile, a traveling herd of dinosaurs visits the Great Valley. Later that night, Littlefoot sees a strange blue-colored meteor falling from the sky and crashing into Threehorn Peak, a volcano in the Smoking Mountain range. When Littlefoot describes it the next morning, the adults in the Great Valley do not believe him except for two newcomers, the mysterious "Gallimimus", who speak about possibilities of Universe. The Rainbow Faces suggest the rock may be a "Comet", which is capable of possessing magical properties.
Ducky's relationship with her brother Spike becomes rambunctious and turbulent when he repeatedly keeps her awake at night with his snoring and after he ate her tree stars (which their mother packed specifically for her on their first day of school). She tells Cera about her feelings, and confides that she does not know how to express them; Cera agrees to teach her. Meanwhile, the children are attending a school in which they are taught by an old ''Pachyrhinosaurus'' named Mr. Thicknose, who professes to have been everywhere and seen everything. Littlefoot eagerly questions the topics they cover, to the old dinosaur's irritation. Eventually, Mr. Thicknose complains to Grandpa Longneck about Littlefoot's behavior. Grandpa, knowing Littlefoot meant no harm, explains to him why he must be more respectful to Mr. Thicknose.
After a period of harsh rain, the Great Valley is partially flooded, and covered in debris. Littlefoot tries to play with his friends, but they are preoccupied: Cera and her father are removing a large log from their nesting area, Ducky and Spike are relocating their nest with their family, and Petrie has gotten a cold. A bored Littlefoot wishes for a brother, but eventually explores on his own, and discovers a large area flooded by the rains. The adults advise their children to stay away, fearing dangerous creatures from the outside may have been washed into the Valley. However, Littlefoot returns, and meets Mo, a playful young ''Ophthalmosaurus'' that had been caught in the floodwater.
Littlefoot has been on many adventures before, but in this new edition to the Land Before Time series, the next adventure may change his life...forever.
Every year, as the warm season approaches, a certain tree in Great Valley blooms with pink flowers. Because of the tastiness of these "treesweets", every dinosaur in the valley wants his/her fair share of it. However, because of this tastiness (and the fact that there seems to be only one such tree in the whole valley), there is hardly enough for everyone. Because of this, none may eat any of the treesweets until the day they "reach the peak of their tastiness".
Petrie and his siblings get ready to fly for the Day of the Flyers, but Petrie is frustrated that he keeps flying out of formation. While practicing, he meets Guido, a Microraptor who does not know what he is, or where he belongs. With the help of Guido, Petrie learns how to be himself and stand out from the crowd.
Littlefoot, a young Apatosaurus living in the verdant Great Valley, is eagerly awaiting the arrival of his father Bron, who returns to the valley with his herd once a year. However, he soon learns from a ''Nothronychus'' member of his dad's troupe named Wild Arms that his father became stranded in the wilderness when the ''fire mountain'' erupted, leaving the rest of the herd to go on without him. They ask Wild Arms for help, but he belligerently says no. The other grownups agree. After worrying about his father, Littlefoot sets out alone. However, the others soon catch up with him. They do fine at first, but run into the ''earth divide''. It is suggested that they follow the ''Long Valley'' instead, but Littlefoot says that that will take too long, and that they must cross there. Luckily, they are able to knock down a tree, and get across.
Join the adventures of the dinosaurs from The Land Before Time in this animated series. Don't miss out as they explore their world and have cool adventures in the Great Valley and the Mysterious Beyond.
