Dinosaurs for my Eldest Son

Here I am again, it's like a line of a song, huh? Well I'm thinking something to type on in my post. And I realize this topic, this is about my son's favorite book of dinosaurs. He bought this last Christmas. This book tells the story of the evolution of animals on Earth-- from the first shelled creatures to mammals. I was wondering that my 4 years old son likes this book so much, imagine he is 4 years old. Even he can't read all the lines there because he just beginning to read small words, he is enjoy looking the animals featured, especially the dinosaurs. He has also the collection of this toy-dinosaurs.