New insights into the ontogeny of Paranthropus boisei offered by a juvenile upper masticatory apparatus from the Shungura formation (Ethiopia).

Early hominin juvenile fossils are key for elucidating the developmental basis of adult phenotypic variation and enhancing our understanding of phylogenetic relationships. Since the discovery of the Taung child a century ago, numerous findings have expanded our knowledge concerning craniodental ontogeny of Australopithecus africanus and A. afarensis, and more recently, Paranthropus robustus. However, less is known about the highly-derived, robust species P. boisei from eastern African. In this study, we present a juvenile specimen of P. boisei recently recovered from the Shungura Formation (Ethiopia), offering insights into the craniodental development of eastern African robust hominins. To give an age at death, the dental developmental stage was studied and compared to those of P. robustus individuals. We then examined the expression of derived morphological features in the studied individual, comparing them to those observed in various published fossils, in order to explore the craniofacial ontogeny of the genus Paranthropus. Our results show that OMO 362-10001 age at death is estimated to have been around 3.8 to 5 years old. The OMO 362-10001 maxillary morphology indicates that some of the derived features shared by species of Paranthropus are already evident by this stage of development while others are not. This present ontogenetic pattern differs in some way from that of P. robustus, suggesting ontogenetic variation within the clade Paranthropus.