Plesiadapiformes ("Adapid-like" or "near Adapiformes") is an extinct (and possibly paraphyletic or polyphyletic   ) order of mammals. It is either closely related to the primates or a precursor to them. Many are too derived to be ancestral to primates, but the earliest Plesiadapiformes had teeth that are strongly indicative of a common ancestor. Purgatorius is believed to be close to the last common ancestor of primates and Plesiadapiformes.