Pachydermata is an obsolete order of mammals described by Gottlieb Storr, Georges Cuvier, and others, at one time recognized by many systematists. Because it is polyphyletic, the order is no longer in use, but it is important in the history of systematics.

What makes a pachyderm?

: any of various nonruminant mammals (such as an elephant, a rhinoceros, or a hippopotamus) of a former group (Pachydermata) that have hooves or nails resembling hooves and usually thick skin especially : elephant.

Is a giraffe a pachyderm?

Today this includes just elephants but at the time nearly every big and thick-skinned herbivore was a “pachyderm”, even giraffes, hippos and rhinos,. All of these were known from good fossil remains, with the exception of one. A prehistoric giraffe was rather new to science.