[2] Trinidad's first professional credits included illustrating novelist Marcial Buanno’s Guido Mortal and Arkong Bato in the late 1960s.
[6] Trinidad supplied full art or inks over other artists (frequently John Romita Sr. and John Buscema) on horror titles such as Vampire Tales (Morbius the Living Vampire stories written by Doug Moench), Dracula Lives!, Marvel Chillers, and The Son of Satan, as well as fantasy and adventure titles like Skull the Slayer, The Savage Sword of Conan, and Deadly Hands of Kung Fu.
Other highlights of Trinidad's tenure at Marvel included "Hellfire Helix Hex!," written by John Warner, for Marvel Presents #2 (Dec. 1975); in addition, Trinidad inked the feature story (written by Bill Mantlo and penciled by Tom Sutton) in Man From Atlantis #1 (Feb.
[8] With writer Roy Thomas and penciler John Buscema, Trinidad adapted Robert E. Howard's "The Pool of the Black One" in Savage Sword of Conan #22–23 (Sept.–Oct.
And with writer Doug Moench, Trinidad adapted H. G. Wells' The Food of the Gods and How It Came to Earth for Marvel Classics Comics #22 (1977).