Orang-outang, Sive Homo Sylvestris, or the Anatomy of a Pygmie Compared with that of a Monkey, an Ape, and a Man by Edward Tyson, was the first published anatomy of an ape. The animal that Tyson refers to as an "orang-outang" and "pygmie" is actually most likely an African chimpanzee. Tyson used the ape's anthropoid features to establish a hierarchical relationship between monkeys, apes, and humans, foreshadowing theories of evolution and first formulating the idea of the missing link. It contains 8 folded plates engraved by Michael van der Gucht after drawings by William Cowper.