If your interest in orangutans and monkeys leads you to pursue a career studying them, your specialty will be primatology, the study of mammals like apes, gorillas, baboons, and lemurs.
A zoologist whose primary interest is primates is a primatologist, and their field is primatology. All of these words stem from the Late Latin primas, "of the first rank," and its root, primus, "first." Scientists think of primates as "the first, or highest, order of mammals." You may agree if your interest in primatology has led you to put apes and monkeys at the top of your list of interesting animals.