An earthquake separates the main characters from their families, and they set off to reunite with them as they embark on an adventure to The Great Valley. They face dangers such as starvation, Sharpteeth, and splitting up.
Soon after arrival in the Great Valley, the little dinos chase some Egg Stealers into the Mysterious Beyond and discover an egg from which a Sharptooth hatches. They call him Chomper, and all is well until he gets interested in Cera's tail, bites it, and gets in trouble. But they made a hole in the Great Wall and the Egg Stealers are out for revenge.
The gang is in some trouble with bullies, but then a much bigger problem appears. The Thundering Falls stop and the valley starts drying out. To make things even worse (for the main characters) Cera's grouchy but well-meaning father bans her from playing with Littlefoot!
A herd of farwalker longnecks visits the valley, telling that their homeland was transformed into the Land of Mists. Grandpa Longneck then becomes mortally ill and Littlefoot, along with a young longneck from the herd named Ali, sets out to find the cure: the Night Flower, which grows in... the Land of Mists! Little foot goes on an adventure with Ali, except Ali is afraid of his friends.... But things change when she must find help to save Littlefoot- and save his grandpa!
Leaf gobblers appear and eat all of the green food in the Great Valley and the herds leave. The gang set out to find green food so their herds will not break up after a disagreement. While doing this they wind up on an island and meet a friend they have not seen in a while. Chomper! Chomper is now old enough to talk- and Cera is suspicious about his kind- AND HIS MOM AND DAD!
A large longneck named Doc appears in the valley, and Littlefoot believes him to be the Lone Dinosaur of legend. Later Littlefoot and his friends accidentally break off one of the stone teeth of Saurus Rock when searching for Cera's niece and nephew, Dinah and Dana- who cause trouble for Cera! and as told in the legend bad luck seems to descend upon the valley. Unfortunately the adults blame Doc!
Littlefoot sees a strange flying rock one night while everyone is sleeping. The valley has some visitors, among them Petrie's uncle Pterano and some rainbowfaces that seem to talk in riddles and explain that the rock may be a "Stone of Cold Fire". Ducky is taken captive by Pterano and his henchmen and the gang set out to save her from her captors who have set out to capture the stone of cold fire for themselves.
Some spiketail farwalkers visit the valley. During their visit snow falls upon the valley. Spike, who has befriended Tippy, goes with the spiketails. Ducky sets out to bring Spike back and the gang set out to save Ducky. Meanwhile, Mr.Thicknose seeks trouble upon Littlefoot, and spills a deep secret.
During a bad rainy season more rain than usual falls upon the Great Valley, so much that it floods part of it. Littlefoot meets a happy, funny talking little fish named Mo, who lives there but also a huge swimming sharptooth. An earthshake traps the gang and they go on a journey to get home - returning their new friend on the way. Also, Cera is a tad annoyed with Mo, who doesn't want to be serious. Though things change in the end.
Littlefoot has odd dreams. He finds out his grandparents have also and it means they must set out and travel to a destination they have not seen. His friends set out after he has left to catch up. But a surprise is in store for Littlefoot once he reaches their destination.
It is almost time for the Great Valley herd to have some of the tree sweets. Something knocks them down and it is discovered some tiny dinos have moved into the Great Valley. Littlefoot makes some new friends, like Skitter and Lizzie. But must make a difficult decision. Meanwhile, Cera's father falls in love with an old friend, Tria, but does Cera agree with having a mother?
It is an important time for Petrie, and possibly emotional time showing he can fly with his family. Also Cera learns some news concerning her family: a new baby, Tricia! While this occurs they also meet a new friend Guido, but what is he? no one knows, not even him!
Some Cocky Yellow Bellies, Loofah, Doofah, and Foobie appear in the Great Valley. They are trying to find their way to Berry Valley. The gang sets out to help them find their way there. Littlefoot also tries to teach them the Wisdoms.
Chomper's cave starts leaking, so the gang searches for a new cave Chopper can stay in while he lives in the valley.
The gang tries to find someone who can help explain why Chomper has lost a tooth to see if it's normal.
Ruby's first Star Day (her birthday) in the Great Valley has Ruby missing her family. But when the other kids decide to throw a surprise "Giving Ceremony" to make Ruby feel better, their secretive preparations result in Ruby feeling even lonelier!
Cera accidentally loses Tria's shiny stone, so the gang travels to the Canyon of Shiny Stones looking for a new stone to replace the lost one.
Ducky invents a new game while trying to get a tree sweet, and now everyone is anxious to see who can win the log-running cmopetition.
Ali's herd returns to the valley, and a new dinosaur named Rhett claims sharptooth's fear him, so the gang decides to bring in Chomper to see if he is a liar.
Ruby and Chomper tell the other kids about a place where water jumps out of the ground, and they head out to see it. Meanwhile, Petrie frets that the tree stars Spike ate will bring them bad luck.
A storm destroys Petrie's nest, and Ducky tries to teach Tricia how to swim.
An earthshake traps Ducky and Chomper on a ledge with the sharptooth Thud, who is pinned down by rocks. In the end, Chomper and Thud discover which of them is the "bigger" sharptooth!
The kids discover a canyon of fruit trees and decide to keep it secret, but things may have to change when the Sharp Teeth decide to use it as an entrance to the canyon.
When Grandpa Longneck's old friend Saro comes to visit, the kids discover that Grandpa used to be a legendary Story Speaker.
Everyone except Cera and her father are excited for the bright circle celebration, but when fire threatens everyone only Cera and her father can save the day.
It's lonely being the only Sharptooth in the Great Valley. Chomper decides to go to the Mysterious Beyond to teach the Sharpteeth how to be friends. But the Sharpteeth he meets aren't very friendly, as he soon runs into Red Claw and his Fast Biters!
After an earthshake dries up the fast-water, the dinosaur kids try to fix the problem by removing the rocks. On the way, they meet their old friend Mo.
One night, Ruby tells the group a scary story about an invisible dinosaur named 'Hidden Runner and gives everyone scary sleep stories. They see Mr Thicknose to tell him that she made up the story and there is nothing to worry about, but the story of Hidden Runner was true, and they decide to venture into the Mysterious Beyond to search for him.
Doc returns to the great valley, in search of a lady friend. But when he finds out Littlefoot is friends with a sharptooth, their friendship gets strained.
When Spike falls down a hole, he encounters a colony of mammals who thinks of him as the 'Big One' from the Mysterious Above. Meanwhile, his friends try to save him but only find trouble when Mr Thicknose and Topsy can't agree on what to do.
Tippy and his family return to the great valley, much to Spike's delight. But a dispute over food leaves them being forbidden to play with one another.
When Cera accidentally makes falling rocks scare away a group of Belly-Draggers, the dinosaurs think she is a hero. Cera loves the attention, but things get out of hand when the Belly-Draggers return.
Littlefoot's father and Shorty travel to the Great Valley to give Littlefoot the news that he will be taking the "Big Longneck Test", a three-stage test to see if a Longneck is capable of leading a herd. Meanwhile, Shorty tries to lead Littlefoot's friends on an adventure.
While trying to learn how to fly Guido is blown into a cave with Petrie, and they encounter a blind old flyer called Swooper.
On the day of the Falling Rocks of Many Nights (meteor shower), Ruby remembers a memory of her family meeting at Hanging Rock when she lived in the Mysterious Beyond. Ruby adventures alone to find her family, but her friends come along to help. They meet Skip along the way, a mammal who knows the Mysterious Beyond very well, and the gang learns an important lesson of being family.
A herd of sand creepers (crabs) comes to the Great valley, so the gang decides to investigate why they are there.
A rainbow is mistaken as being sky stones. When it disappears, the gang decides to see where it has run off to.
A freeze has come to the Great Valley, so Mr. Thicknose decides to tell everyone about a mysterious treat known as Hard Water Sweets (which are frozen grapes). The gang desires to taste this treat, so the embark on a journey to find them.
The series finale. Littlefoot, Ducky, Petrie and Chomper (followed by Hyp, Nod and Mutt) find a nest of Fast Biter eggs. They decide to carry the eggs away from the valley so the baby sharpteeth can grow up without eating anyone and set off on a journey into the mysterious beyond. They don't know that the mother sharptooth is in hot pursuit though, and she wants her eggs back at all costs.
Littlefoot and friends set out to on an adventure to find his father after he doesn't return from an important journey.
