@inbook{ccc0ce47a4c04aadb29ca591bf0e14bd,
title = "Aspects of mandibular ontogeny in Australopithecus afarensis",
abstract = "Human and ape mandibles differ in the proportion of adult size attained at equivalent dental emergence stages; for most dimensions human mandibles are more advanced. These dissimilarities in pattern of growth underlie the vastly different adult mandibular morphologies of these taxa. Australopithecus mandibles represent a third distinctive mandibular morphology, but the pattern of its mandibular growth remains underexplored. The Australopithecus afarensis sample from the Hadar site, Ethiopia, ca. 3.4–3.0 Ma, is represented by three infant (pre-M1 emergence) and two juvenile (pre-M3 emergence) mandibles. A recently recovered mandible, A.L. 1920-1, though edentulous, appears to capture an A. afarensis individual during M2 emergence, thus bridging these developmental stages. In this chapter, we (1) describe three new infant/juvenile A. afarensis mandibles and confirm that the suite of features used to distinguish A. afarensis from other taxa is present early in ontogeny, and (2) investigate how the A. afarensis mandible changes in size and shape throughout growth in comparison to humans and chimpanzees. Our results indicate that A. afarensis resembles humans more than chimpanzees in its percentage of adult corpus breadth attained at successive stages of dental emergence. A. afarensis is also more similar to humans in corpus cross-sectional shape changes throughout ontogeny. We suggest that canine reduction may have had an important influence on the growth trajectory of the A. afarensis mandibular corpus such that, as in humans, it achieved adult values relatively early. Our results underscore the importance of considering the influence of the developing dentition on both juvenile and adult mandibular morphology.",
keywords = "Australopithecus afarensis, Chimpanzee, Hadar, Homo, Mandibular growth, Tooth eruption",
author = "Halszka Glowacka and William Kimbel and Donald Johanson",
note = "Funding Information: We thank Gary Schwartz and two anonymous reviewers for comments on the manuscript that improved the final product. We are grateful to Terrence Ritzman for help with the comparative sample and Lyman Jellema and Arelyn Simon for access to skeletal collections at the Cleveland Museum of Natural History and the Archaeological Research Institute at Arizona State University, respectively. This study was funded by the Institute of Human Origins and a Sigma Xi Grant-In-Aid of Research to HG. Funding Information: Acknowledgments We thank Gary Schwartz and two anonymous reviewers for comments on the manuscript that improved the final product. We are grateful to Terrence Ritzman for help with the comparative sample and Lyman Jellema and Arelyn Simon for access to skeletal collections at the Cleveland Museum of Natural History and the Archaeological Research Institute at Arizona State University, respectively. This study was funded by the Institute of Human Origins and a Sigma Xi Grant-In-Aid of Research to HG. Publisher Copyright: {\textcopyright} Springer International Publishing AG 2017.",
year = "2017",
doi = "10.1007/978-3-319-46646-0_10",
language = "English (US)",
series = "Vertebrate Paleobiology and Paleoanthropology",
publisher = "Springer",
number = "9783319466446",
pages = "127--144",
booktitle = "Vertebrate Paleobiology and Paleoanthropology",
edition = "9783319466446",
}