The Pachydermata (meaning "thick skin")'s an obsolete order of mammals described by Georges Cuvier and at one time recognized by many systematists. Because it's polyphyletic, the order Pachydermata's no longer in use, but it's important in the history of systematics. Although it's often described as an artificial grouping of unrelated mammals, it was recognised as a grade of hooved mammals to the exception of other Ungulates by zoologists such as Charles Darwin, and anatomical characters do supp… (More on Pachydermata)