During the 1980s, Mackal turned his attention to purported creature, the Mokele-mbembe, which figures such as Young Earth creationists claim is a living dinosaur in the Likouala swamp region of the Republic of Congo. Accompanied by University of Arizona ecologist Richard Greenwell and Congolese biologist Marcellin Agnagna, Mackal undertook two expeditions, the first in 1980 and the second in 1981, to find and photograph the creature. Mackal himself did not actually see the creature, but he and his colleagues did collect multiple firsthand reports from Congo natives, who, according to Mackal, consistently described a creature similar to a long-necked sauropod. During his interviews with the natives, Mackal also heard anecdotes about the Emela-ntouka, another possible living dinosaur which supposedly resembles a "Monoclonius" or "Centrosaurus", the Mbielu-Mbielu-Mbielu, which is said to resemble a "Kentrosaurus", and the snake- or lizard-like Nguma-monene.