The entire Mane 6 find themselves in a harsh no ponies land filled with dinosaurs after a transition to the human world via Canterlots' magic mirror goes astray.
With the unicorns having their magic weakened for some reason and a heavier air, making it harder for the pegasus in the group to fly, the ponies will have to find a way through the treacherous Land Before Time.
On their way they meet a young adult apatosaurus by the name of Littlefoot. He is currently scared by events that caused him to abandon his friends and his herd to survive the wildlands alone. Littlefoot barely has time to ask the ponies what the symbols on their flanks are before he is engulfed in a bright light and recives a cutie mark of his own, a white star that doesn't say Twilight Sparkle, the leader of the pony group, anything.
Will Littlefoot be able to help the ponies get back to Equestria again? - Will the ponies be able to help Littlefoot discover the purpose of his cutie mark? - May the destinies of the prehistoric creature and the ponies be entwined? - Or may there be a chain of events in motion that none of the parties expected? The great circle of life may have the answer.
They also meet a lot of dangers. In a harsh world where food is scarce predators need to feed to.
Note 02-05-2019: About to add more chapter soon. In the meantime I will take time to rewrite some other chapters, add more character expressions and make the text more readeble. Also, before anyone points out the countless holes that I'm sure it will create: No. I have not seen the LBT TV show. My story is soely based on the films.