Here are the best Dinosaur Story Books for Preschoolers;
Dinosaurs, Dinosaurs by Byron Barton
A long time ago, dinosaurs roamed the earth. Both large and small dinosaurs. There have been dinosaurs with horns on their heads and spikes running down their backs. The dinosaurs had long, long necks and long, long tails. It will amaze you to see how they manage to say impossibly long dinosaur names.
Bones, Bones, Dinosaur Bones by Byron Barton

Young readers will explore the process of discovering and assembling dinosaur fossils with the easy text and colorful illustrations.
Saturday Night at the Dinosaur Stomp by Carol Diggory Shields

A delightful picture book about dinosaurs that your children will be begging you to read again and again. Do you know what dinosaurs used to do for fun?
National Geographic Little Kids First Big Book of Dinosaurs by Catherine D. Hughes

Every spread features a different dinosaur and includes age-appropriate nonfiction information, along with simple text in big type that’s great for young children.
Dinosaur Bones by Bob Barner

Dinosaur Bones will keep dinosaur enthusiasts entertained with fun dinosaur facts (a T. Rex skull weighs up to 750 pounds!) and an informational “Dinometer.”
The Dinosaur Alphabet Book by Jerry Pallotta

Children will love exploring the fascinating world of dinosaurs with this book. You might be surprised to learn that some dinosaurs had sharp front teeth while others had no front teeth at all? This alphabet book explores well-known and not-so-well-known dinosaurs, creating a challenge for even the biggest dinosaur fans!
Ten Terrible Dinosaurs by Paul Stickland (1997, Ages 3-5 years)

Discover a wild group of romping, stomping dinosaurs as they leap, leap, and dance across the pages. The dinosaurs leave one by one until only one is left.
Dinosaur Roar! by Henrietta Strickland (Age: 2-4 years)
Dinosaurs in all shapes and sizes, whether sweet, grumpy, spiky, or lumpy. A good introduction to opposites. You could make a class book around it!
If the Dinosaurs Came Back By Bernard Most (1984)
In this charming tale, a small boy imagines a world in which dinosaurs are responsible for public services. Imaginative and humorous illustrations enhance the story. Student responses are natural: Students develop their own scenarios about what would happen if dinosaurs returned. The reading teacher says it’s a favorite with young kids.