TY - JOUR
T1 - Evolution of the mandibular third premolar crown in early Australopithecus
AU - Delezene, Lucas K.
AU - Kimbel, William
N1 - Funding Information:
We thank the staff of the National Museum of Ethiopia, especially General Manager Mamitu Yilma and casting expert Alemu Ademassu, for granting access to the Hadar specimens; Dr. Emma Mbua, the staff of the National Museums of Kenya, and Dr. Meave Leakey for permission to study the A. anamensis and Lomekwi fossils; Lyman Jellema for providing access to and assistance with the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History; and Malcolm Harmon and the staff of the Powell-Cotton Museum for access to and assistance with their collection. We also thank Linda Gordon (Smithsonian Museum of Natural History), Bill Stanley (Field Museum of Natural History), and Eileen Westwig (American Museum of Natural History) for permission to access their collections. We are grateful to Dr. Zeresenay Alemseged for providing a cast of DIK-2-1 and permitting us to study the original specimen, Dr. Michel Brunet for providing a cast of the P 3 s of KT 12/H1 and allowing us to include data collected from this specimen, and the late Dr. Charles Lockwood for providing the Excel macros used to perform the permutation tests, bootstrapping procedures, and tests of temporal trends that were used in this analysis. We thank Dr. Matt Tocheri for helpful discussions related to statistical testing and comments on an early version of this manuscript. Comments from three anonymous reviews and those of editor Dr. Steve Leigh greatly improved the manuscript. A portion of the data analyzed here was collected as part of LKD’s Masters-in-passing thesis research, which benefited from the financial support of the Research and Development Committee of the School of Human Evolution and Social Change and the Institute of Human Origins at Arizona State University . Data collection was also funded by a Wenner-Gren Doctoral Dissertation Fieldwork Grant and NSF Doctoral Dissertation Improvement Grant (# 0852105 ) to LKD (under WHK).
PY - 2011/6
Y1 - 2011/6
N2 - The Pliocene hominins Australopithecus anamensis and Australopithecus afarensis likely represent ancestor-descendent taxa-possibly an anagenetic lineage-and capture significant change in the morphology of the canine and mandibular third premolar (P3) crowns, dental elements that form the canine honing complex in nonhuman catarrhines. This study focuses on the P3 crown, highlighting plesiomorphic features in A. anamensis. The A. afarensis P3 crown, in contrast, is variable in its expression of apomorphic features that are characteristic of geologically younger hominins. Temporal variation characterizes each taxon as well. The A. anamensis P3 from Allia Bay, Kenya expresses apomorphic character states, shared with A. afarensis, which are not seen in the older sample of A. anamensis P3s from Kanapoi, Kenya, while spatiotemporal differences in shape exist within the A. afarensis hypodigm. The accumulation of derived features in A. afarensis results in an increased level of P3 molarisation. P3 molarisation did not evolve concurrent with postcanine megadontia and neither did the appearance of derived aspects of P3 occlusal form coincide with the loss of canine honing in hominins, which is apparent prior to the origin of the genus Australopithecus. A. afarensis P3 variation reveals the independence of shape, size, and occlusal form. The evolution of the P3 crown in early Australopithecus bridges the wide morphological gap that exists between geologically younger hominins on the one hand and extant apes and Ardipithecus on the other.
AB - The Pliocene hominins Australopithecus anamensis and Australopithecus afarensis likely represent ancestor-descendent taxa-possibly an anagenetic lineage-and capture significant change in the morphology of the canine and mandibular third premolar (P3) crowns, dental elements that form the canine honing complex in nonhuman catarrhines. This study focuses on the P3 crown, highlighting plesiomorphic features in A. anamensis. The A. afarensis P3 crown, in contrast, is variable in its expression of apomorphic features that are characteristic of geologically younger hominins. Temporal variation characterizes each taxon as well. The A. anamensis P3 from Allia Bay, Kenya expresses apomorphic character states, shared with A. afarensis, which are not seen in the older sample of A. anamensis P3s from Kanapoi, Kenya, while spatiotemporal differences in shape exist within the A. afarensis hypodigm. The accumulation of derived features in A. afarensis results in an increased level of P3 molarisation. P3 molarisation did not evolve concurrent with postcanine megadontia and neither did the appearance of derived aspects of P3 occlusal form coincide with the loss of canine honing in hominins, which is apparent prior to the origin of the genus Australopithecus. A. afarensis P3 variation reveals the independence of shape, size, and occlusal form. The evolution of the P3 crown in early Australopithecus bridges the wide morphological gap that exists between geologically younger hominins on the one hand and extant apes and Ardipithecus on the other.
KW - Australopithecus afarensis
KW - Australopithecus anamensis
KW - Canine honing complex
KW - Hadar
KW - Kanapoi
KW - Laetoli
KW - Premolar molarisation
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U2 - 10.1016/j.jhevol.2011.01.006
DO - 10.1016/j.jhevol.2011.01.006
M3 - Article
C2 - 21481921
AN - SCOPUS:79955475780
VL - 60
SP - 711
EP - 730
JO - Journal of Human Evolution
JF - Journal of Human Evolution
SN - 0047-2484
IS - 6
ER -