Dinosaurs and Operating systems

I have been reading the book "operating system principles" by Silberschatz, Galvin and Gagne for my mid sems.. and everywhere in the book, there are pictures of dinosaurs. Even on the cover page. there's a dinosaur. Its not just the 7th edition.. there are different photographs of dinosaurs in different editions of the book.

I have spent more time on figuring out the relationship between OS n dinosaurs than I have spent in the content of the book. And still I have not been able to solve the mystery.. Anyone help me out?