a massive silverback gorilla beats his chest while standing on a sturdy tree branch. A curious chimpanzee swings from vine to vine nearby, reaching toward hanging fruit. The gorilla's powerful display causes leaves to shake and fall around them. An orangutan with long reddish hair sits peacefully on another branch, observing the interaction. Smaller monkeys with long tails scatter to higher branches, clearly intimidated by the larger tailless primates. large primates that lack tails, including gorillas, chimpanzees, and orangutans