The restored lower jaw of Arcanotherium (formerly Numidotherium savagei). (From Delmer, 2009)

Unlike the folks at this past weekend’s ScienceOnline 2010 meeting, fossils don’t come with nametags. The identification of preserved bits of ancient life relies upon careful comparison with what is already known, a task made all the more difficult for vertebrate paleontologists by the fragmentary nature of many of their subjects. Scraps of bone given one name could turn out to be parts of another partial skeleton given another name, or other bits of bone attributed one name could turn out to be something entirely new. Reexaminations and revisions are ongoing, and one effort to rearrange a petrified puzzle led to the origin of a