Taxonomy illustrations are in and of themselves a kind of art, one that seeks to help us better understand and organize nature. These detailed drawings of skeletons, situated inside a silhouette of the full-bodied animal, are particularly beautiful and informative. They come from a series called "Die vergleichende Osteologie", or Comparative Osteology—a study of skeletal structure and function. Created by Christian Heinrich Pander and Eduard d’Alton, it was published in Bonn, Germany between 1821 and 1838. The images have been published online by the Biodiversity Heritage Library.
This illustration shown here is of a common ostrich (Struthio camelus). Notice that the ostrich only has two toes—whereas most birds have four.