title: A radiographic study of permanent molar development in wild Virunga mountain gorillas of known chronological age from Rwanda.
abstract: While dental development is important to life history investigations, data from wild known-aged great apes are scarce. We report on the first radiographic examination of dental development in wild Virunga mountain gorillas, using known-age skeletal samples recovered in Rwanda.
  
  
  
  In 43 individuals (0.0-14.94 years), we collected radiographs of mandibular molars, and where possible, cone beam CT scans. Molar crown and root calcification status was assessed using two established staging systems, and age prediction equations generated using polynomial regression. Results were compared to available data from known-age captive and wild chimpanzees.
  
  
  
  Mountain gorillas generally fell within reported captive chimpanzee distributions or exceeded them, exhibiting older ages at equivalent radiographic stages of development. Differences reflect delayed initiation and/or an extended duration of second molar crown development, and extended first and second molar root development, in mountain gorillas compared to captive chimpanzees. However, differences in the duration of molar root development were less evident compared to wild chimpanzees.
  
  
  
  Despite sample limitations, our findings extend the known range of variation in radiographic estimates of molar formation timing in great apes, and provide a new age prediction technique based on wild specimens. However, mountain gorillas do not appear accelerated in radiographic assessment of molar formation compared to chimpanzees, as they are for other life history traits. Future studies should aim to resolve the influence of species differences, wild versus captive environments, and/or sampling phenomena on patterns observed here, and more generally, how they relate to variation in tooth size, eruption timing, and developmental life history.
authors.affiliation: Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, 20052.|Department of Anthropology, University of Pennsylvania, Philadelphia, Pennsylvania, 19104.
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Kralick
authors.affiliation: Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21218.
authors.forename: M
authors.initials: M
authors.lastname: Loring Burgess
authors.affiliation: Institute of Human Origins, School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, 85287.
authors.forename: Halszka
authors.initials: H
authors.lastname: Glowacka
authors.affiliation: Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, 20052.
authors.forename: Keely
authors.initials: K
authors.lastname: Arbenz-Smith
authors.affiliation: Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, 20052.
authors.forename: Kate
authors.initials: K
authors.lastname: McGrath
authors.affiliation: Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21218.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Ruff
authors.affiliation: Department of Oral and Maxillofacial Pathology, Radiology and Medicine, New York University College of Dentistry, New York, 10010.
authors.forename: King Chong
authors.initials: KC
authors.lastname: Chan
authors.affiliation: Mountain Gorilla Veterinary Project, University of California at Davis, California, 95616.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Cranfield
authors.affiliation: Dian Fossey Gorilla Fund International, Atlanta, Georgia, 30315.
authors.forename: Tara S
authors.initials: TS
authors.lastname: Stoinski
authors.affiliation: Hard Tissue Research Unit, Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, 10010.|Hard Tissue Research Unit, Department of Basic Sciences and Craniofacial Biology, New York University College of Dentistry, New York, 10010.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Bromage
authors.affiliation: Department of Tourism and Conservation, Rwanda Development Board, Kigali, Rwanda.
authors.forename: Antoine
authors.initials: A
authors.lastname: Mudakikwa
authors.affiliation: Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, 20052.|Division of Mammals, National Museum of Natural History, Smithsonian Institution, Washington, DC.
authors.forename: Shannon C
authors.identifier: 0000-0003-3411-1297
authors.initials: SC
authors.lastname: McFarlin
mesh_terms: D000818:Animals; D000885:Anthropology, Physical; D005260:Female; D006071:Gorilla gorilla / Q000254:growth & development*; D008297:Male; D008963:Molar / Q000000981:diagnostic imaging* / Q000254:growth & development*; D011861:Radiography, Dental; D012432:Rwanda
keywords: Gorilla beringei beringei; dental development; radiographs