Curiously, the Sinclair family members all appear to belong to wildly different species of dinosaurs. Humans have appeared in several episodes as cavemen, and the dinosaur characters often expressed the belief that humans could never develop intelligence. Earl’s favorite show on T.V. features a talking caveman named “Mr. Ugh”, a direct parody of Mr. Ed, further expressing the dinosaurs’ belief that humans are stupid. A recurring joke is that the dinosaurs do not know how to tell male and female humans apart and usually switch them in conversation, or as shown in one episode, “The Mating Dance”, in which zookeepers unknowingly pair two obviously male humans together and cannot figure out why they will not produce offspring.
