Tooth chipping patterns and dental caries suggest a soft fruit diet in early anthropoids

Fossils from the Fayum Depression, Egypt, are crucial for understanding anthropoid evolution due to the abundance of taxa and the time interval they represent (late Eocene to early Oligocene). Dietary and foraging behavioral interpretations suggest fruits were their dominant food source, although hard foods (e.g., seeds and nuts) and leaves could have been important dietary components for particular groups. In this study, we compare dental chipping patterns in five Fayum primate genera with chipping data for extant primates, to assess potential hard object feeding in early anthropoids.

Original specimens were studied (Aegyptopithecus: n = 100 teeth; Parapithecus: n = 72, Propliopithecus: n = 99, Apidium: n = 82; Catopithecus: n = 68); with the number, severity, and position of chips recorded. Dental caries was also recorded, due to its association with soft fruit consumption in extant primates.

Tooth chipping was low across all five genera studied, with a pooled chipping prevalence of 5% (21/421). When split into the three anthropoid families represented, chipping prevalence ranged from 2.6% (4/154) in Parapithecidae, 6% (12/199) in Propliopithecidae, and 7.4% (5/68) in Oligopithecidae. Three carious lesions were identified in Propliopithecidae.

The chipping prevalence is low when compared to extant anthropoids (range from 4% to 40%) and is consistent with a predominantly soft fruit diet, but not with habitual hard food mastication. The presence of caries supports consumption of soft, sugary fruits, at least in Propliopithecidae. Our results add support for low dietary diversity in early anthropoids, with soft fruits as likely dominant food sources.