The juvenile mandible is important in the investigation of ontogenetic and evolutionary changes among early hominins. We revisit the mandibular symphysis in juvenile specimens of Australopithecus africanus and Paranthropus robustus with two main contributions. First, we employ, for the first time, methods of computational anatomy to model complex symphyseal shape differences. Second, we present new fossil evidence from Kromdraai to improve our knowledge of symphyseal morphology. We describe differences between shapes by landmark-free diffeomorphism needed to align them. We assess which features of the mandibular symphysis best discriminate the juvenile symphysis in these fossil species, relative to the intraspecific variation observed among modern humans. Our approach eliminates potential methodological inconsistencies with traditional approaches (i.e., the need for homologous anatomical landmarks, assumption of linearity). By enabling detailed comparisons of complex shapes in juvenile mandibles, our proposed approach offers new perspectives for more detailed comparisons among Australopithecus, Paranthropus and early Homo.
Madagascar's high rates of endemism, paired with its escalating deforestation rates, has made it one of the most important conservation priorities on the planet. In southeastern Madagascar, the Corridor Forestier d'Ambositra Vondrozo (COFAV) is an unprotected rainforest corridor that sustains ∼15 species of lemurs, most of which are endangered. The COFAV connects many protected areas and is therefore essential for gene flow, dispersal, and the long-term sustainability of animal populations in the area. The corridor has not been surveyed extensively since the 1990s, and even so, only a fraction of the sites have been sampled multiple times. The goal of our study was to survey the COFAV, from Ranomafana National Park to the Mananara River, to provide updated species occurrences and ranges. Combining data across multiple teams using different inventorying methods, we surveyed a total area of 227 km2 throughout an eight-month period. We recorded every lemur occurrence (sighting or vocalization) and noted the species, date, time, group size, and GPS coordinates. We found 11 lemur species and one putative hybrid species. The geographic ranges for three species (Hapalemur aureus, H. griseus, Propithecus edwardsi) were larger than previously thought. The range of Varecia variegata should be shortened and adjusted accordingly, as the species appears transient (at best) in the northern parts of Ranomafana National Park and was not found south of the Ambohimahamasina/Ikongo region. This study provides updated geographic ranges for lemur species in the COFAV, important information for future censuses, species assessments, and conservation measures for future implementation.
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