There are 21 known species of cartilaginous fishes from the Urumaco Formation, belonging to the orders Lamniformes, Carcharhiniformes, Myliobatiformes and Rajiformes.
[3] Seven species of caimans have been described: Caiman brevirostris, C. latirostris, Globidentosuchus brachyrostris, Melanosuchus fisheri, Mourasuchus arendsi, M. nativus and Purussaurus mirandai, Gryposuchus croizati, G. jessei, Hesperogavialis cruxenti and Ikanogavialis gameroi are the gavials of Urumaco, a group that is no longer found in South America today.
Multiple species of crocodilians were able to live together because they focused on specific niches, limiting infraspecific competition.
Others ground sloths from Urumaco are Bolivartherium urumaquensis, Urumacotherium garciai, Eionaletherium tanycnemius, and Pseudoprepotherium venezuelanum belonging to the Mylodontidae.
Bounodus enigmaticus (Proterotheriidae, Litopterna) and Gyrinodon (Toxodontidae, Notoungulata) are the South American ungulates of the Urumaco formation.
[13] In the waters of Urumaco lived the freshwater dolphins Ischyrorhynchus vanbenedeni and Saurodelphis and the dugongs Nanosiren sanchezi and possibly Metaxytherium.