I have some suggestions for other easy series your son might enjoy:
Puppy Place by Ellen Miles (shelved under J FICTION MILES)
Magic Tree House (shelved under J FICTION OSBORNE)
A to Z Mysteries (shelved under J SERIES A)
Adventures of the Bailey School Kids (shelved under J SERIES B)
All of these easy chapter books are comparable in length to the Dinosaur Cove series and are popular among other young patrons.
I hope your son will find some of these suggestions enjoyable. Thank you for contacting us!