(DC Comics Presents #35 (fb)) - <years ago> Rex continued to tour with Danny Dennis, but his age was showing, and at a charity circus event Rex botched the tightrope act and felt awful. Rex’s number one fan Bobo the Detective Chimp was in the audience, and met him backstage, and Rex gave Bobo a souvenir from one of his cases. Crooks robbed the circus, and Rex left in pursuit, with Bobo right behind him. They boarded a ship the crooks took off in, and arrived on Bimini Island. Rex fended off local crocodiles, and was gravely injured. Bobo found a nearby stream and brought him water, which they both drank. The water was actually from the legendary Fountain of Youth that Ponce de Leon failed to find, and both animals found themselves restored to their prime. They took down the crooks, and alerted the coast guard.

(DC Comics Presents #35) - Danny Dennis became a Lt. Col. And was a member of the U.S.A.’s latest moon mission. He took Rex along to outer space, and Rex became the first dog on the moon.

(Green Lantern III #30, 31, Flash II #70) - At the Bureau of Amplified Animals Detective Chimp discovered that Gorilla Grodd had escaped captivity in Gorilla City, so he teamed Rex the Wonder Dog up with Danny Dennis and Green Lantern II and sent them to Gorilla City to investigate. They witnessed Grodd and Hector Hammond mentally warring over control over an evolutionary meteorite. Grodd won the struggle and took over Gorilla City, but was defeated by Rex and his allies.