My colleagues and I used information from the DNA sequences of approximately fifty species of the dung beetle genus Onthophagus to arrange taxa into a nested series of groups based on their relatedness. The resulting tree, called a phylogeny, describes the history of these animals and can be used to trace the evolution of particular traits such as horns. This study showed that horns were gained and lost repeatedly in the history of these beetles.

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 707