The Robert Stack Dinosaur appeared in the Dinosaurs episode "The Last Temptation of Ethyl." A take-off of Unsolved Mysteries host Robert Stack, this dinosaur is the deadpan host of Mysteries That Haven't Been Solved Yet. He invites Ethyl Phillips to be a new featured mystery.

After her broadcast, the host remarks, "I was touched. And normally, I am untouchable," referencing Stack's first TV series. He follows it up by calling for his assistants Rico and Youngone to bring his chair (referencing Ness's agents Rico and Youngfellow on The Untouchables).