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Systematic Assessment of Mammalian Skull Specimens for Dental and Temporomandibular Joint Pathology
Published on: August 22, 2022
Brief communication: Molar development and crown areas in early Australopithecus.
Rodrigo S Lacruz1, Fernando V Ramirez Rozzi, Bernard A Wood
1Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA. rodrigo@usc.edu
American Journal of Physical Anthropology
|May 25, 2012
Summary
The study analyzed Australopithecus anamensis and Australopithecus afarensis molar teeth, finding no significant differences in crown areas but suggesting a trend of increasing M(1) crown size and distal cusp expansion during their evolutionary transition.
Area of Science:
- Paleoanthropology
- Hominin evolution
- Dental morphology
Background:
- Australopithecus anamensis and Australopithecus afarensis are considered potential ancestor-descendant species.
- Understanding their dental morphology provides comparative evidence for hominin evolutionary lineages.
Purpose of the Study:
- To analyze and compare the crown and cusp base areas of mandibular molars between Australopithecus anamensis and Australopithecus afarensis.
- To investigate potential evolutionary trends in molar morphology during the proposed Australopithecus transition.
Main Methods:
- High-resolution replicas of mandibular molars from Australopithecus anamensis and Australopithecus afarensis were analyzed.
- Crown and cusp base areas were measured and statistically compared using the Wilcoxon signed rank test.
Main Results:
- No statistically significant differences in overall molar crown areas were found between Australopithecus anamensis and Australopithecus afarensis.
- Australopithecus anamensis M(1) crowns were the smallest sampled, with no significant intraspecies differences in mesial cusp areas.
- Significant differences in cusp areas were observed in Australopithecus afarensis M(2)s and M(3)s, and in the relative proportions of anterior and posterior cusps in some molars of both species.
Conclusions:
- The transition from Australopithecus anamensis to Australopithecus afarensis may have involved a moderate increase in M(1) crown areas.
- Relative expansion of distal cusps might be a key feature of this evolutionary step.
- Dental microstructure analysis indicates M(1) crown formation in Australopithecus anamensis is comparable to Pan and shorter than in Homo sapiens.
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