Dopey is the Marshall family's dinosaur pet.
Dopey is a baby Brontosaurus and is sometimes referred to as the family's pet. Dopey even lets The Marshall's ride around on it's back, Holly Marshall in particular.
Dopey was discovered by Will and Holly while they were getting food. They found the remains of his egg and then found Dopey eating their food. Dopey got stuck in-between two trees. Grumpy was coming to eat Dopey, but Will and Holly helped get him to safety. Soon Dopey followed Holly and Will home.
There Holly taught him how to pull a wagon and fetch although when he fetched the stick he would just eat it. After attracting Grumpy and almost getting himself and Holly eaten, the family decided to take him to the swamp with the other Brontosaurus. The Brontosaurus Emily adopted him.
Dopey returned to visit Holly many times and also helped pull the food wagon in a couple of episodes. Dopey became trapped in tar while trying to rescue Spot. Spot finally got out but left Dopey. Holly, Will, Rick and Cha-Ka found Dopey. They tried many things to rescue Dopey (pulling him out, creating a pulley, and getting Ta and Sa to help) but all failed. Cha-Ka gave up and left leaving the Marshall's alone. Then when all hope was lost Cha-Ka returned with Emily. They tied a rope around Dopey's neck and the other end around Emily's neck. They used torches to back Emily up who pulled Dopey out saving his life.
- Dopey and most other Brontosaurus had pale gray skin.