I was doing some searching through the abstracts for the upcoming AAPA meetings, and I found that the system gave me abstracts for past meetings as well, so I didn’t notice at first when I was seeing some cool undescribed fossil results from years past.
In 2012, Jennifer Conaway and William Kimbel had an abstract discussing A.L. 1901-1, a Hadar mandible with supernumerary molars: “Australopithecus afarensis mandible with supernumerary molars from the Hadar site, Ethiopia”. The presentation was withdrawn but the finding is an interesting data point:
Within the Hadar sample of A. afarensis mandibles containing a complete molar row, 2 out of 21 (9.5%) specimens hold supernumerary M4s. Although the sample size is modest, this frequency is consistent with those reported for large-bodied extant hominoids.
These are not uncommon in gorilla and orangutan samples, but they are very uncommon in human populations today. Maybe the more interesting observation is that this is another Hadar mandible complete enough to have both sides of the dentition preserved. Unfortunately, this specimen does not seem to have been published anywhere yet, but maybe in the upcoming few years we’ll see it.