 Australopiths in general had thick enamel, like "Homo", while other great apes have markedly thinner enamel.Robust australopiths wore their molar surfaces down flat, unlike the more gracile species, who kept their crests.In a 1979 preliminary microwear study of "Australopithecus" fossil teeth, anthropologist Alan Walker theorized that robust australopiths ate predominantly fruit (frugivory).