Date of Graduation

5-2024

Document Type

Thesis

Degree Name

Bachelor of Science in Anthropology

Degree Level

Undergraduate

Department

Anthropology

Advisor/Mentor

Delezene, Lucas

Committee Member/Reader

Plavcan, Michael

Committee Member/Second Reader

Dowling, Ashley

Abstract

Australopithecus afarensis, an extinct human ancestor (ca. 3.75 – 2.95 million years ago) first distinguished in 1978, has a dense fossil record. Until recently, A. afarensis fossils were primarily known from two locations, Laetoli, Tanzania, and Hadar, Ethiopia, that are approximately 1750 kilometers apart. Additionally, there is no temporal overlap between the sites; fossils from Laetoli are older than 3.5 Ma and those from Hadar stretch from 3.4 – 3.0 Ma. For some tooth positions, the Laetoli and Hadar fossils subtly differ in size and shape. Previous research indicated that some of these differences could be attributable to evolutionary change, or “temporal trends,” that occurred within the species. However, due to small sample sizes at critical intervals and potential age and geographical biases, these trends were difficult to conclude with any certainty. Recent discoveries of A. afarensis fossils at Hadar and other sites in Ethiopia have expanded the sample and extended the evidence to include fossils of equivalent age to those at Laetoli. Further, another species, Australopithecus anamensis (4.1 – 3.8 Ma), has been discovered and hypothesized to represent the earliest part of the A. afarensis lineage. This study investigates temporal trends in dental evolution in A. afarensis considering new discoveries and considers whether trends extend across the proposed A. anamensis/afarensis lineage. The pattern that emerges for most teeth is evolutionary stasis across the nearly 1.1 million years represented by the samples of A. anamensis and A. afarensis. Significant trends are found primarily for the canines, mandibular P3, and maxillary P4.

Keywords

Afarensis; Temporal Trends; Dentition; Anamensis

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