Follow is similar to 'come after'. The normal answer to the question would be the animals or creatures that lived on Earth after the dinosaurs.
What followed the dinosaur?
Do you like this joke?
The question 'What followed the dinosaur?' makes us think of what came after dinosaurs in the history of the world. So the answer would be 'animals' or 'people'. But another way to think of the question is 'What comes after the dinosaur's body?' - it's tail.
I hope that helps.
LearnEnglish Kids team