The concept of size is relative — and takes on prehistoric proportions — in a funny and reassuring tale from a maven of children’s books.

Some dinosaurs are small and slow. They take their time in the prehistoric jungle, collecting fruits and leaves and using their tiny teeth to munch them. Some dinosaurs are big and fast. With huge teeth and claws, they steal food from small dinosaurs, and they’re always hungry for more. So when three big dinosaurs come across one small one, what — or who — can save the little plant-eater? Beautifully drawn and brightly colored, Charlotte Voake’s imaginative introduction to the concept of size brims with visual humor and culminates in a sweet surprise ending.