How do paleontologists distinguish between premolars and molars in the fossilized skull of a mature mammal when the PM and M are superficially similar and there is no information about deciduous teeth in that animal? For example, consider a skull like that of a raccoon. Unlike its upper, two-rooted PM1-PM3 its upper PM4 is three-rooted. Without having juvenile skulls to show there is a deciduous precursor to PM4 how would one know this is a premolar and not another three-rooted molar? Thanks. Edit: Should have said "no information..." submitted by /u/Dracunculus_Rex [link] [comments]