Teeth grow incrementally and preserve within them a record of that incremental growth in the form of microscopic growth lines. Studying dental development in extinct and extant primates and its relationship to life history and ecological parameters (e.g., diet, somatic growth rates, gestation length, age at weaning) holds the potential to yield unparalleled insights into the life history profiles of fossil primates. In this paper, we use the incremental growth record preserved in teeth to reconstruct dental development, and thereby infer the life history of Megaladapis edwardsi, a giant, gorilla-sized, extinct lemur of Madagascar. By examining the microstructure of the first and developing second molars of a juvenile individual, we establish its chronology of molar crown development (M1 CFT = 1.04 years; M2 CFT = 1.42 years) and determine its age at death (1.39 years). Crown initiation, formation, and completion times are short compared to Gorilla. Microstructural data on prenatal M1 crown formation time allow us to calculate a minimum gestation length of 0.54 years for M. edwardsi, compared to 0.70 years in Gorilla. Postnatal crown and root formation in M. edwardsi data allow us to estimate the age at M1 emergence (∼0.9 years), and to establish a minimum age for M2 emergence (>1.39 years).If Megaladapis were developmentally similar to large-bodied anthropoids (such as gorillas), we might expect to exhibit slow dental development coupled with relatively early replacement of its deciduous molars. This is not the case. Total molar development is comparatively rapid and poorly explained as a function of adult body mass.