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Full text release has been delayed at the author's request until December 20, 2026

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Features of catarrhine posterior dental crowns associated with durophagy: Implications for fossil hominins

O'Hara, Mackie Clare
http://orcid.org/0000-0002-1221-0668
http://rave.ohiolink.edu/etdc/view?acc_num=osu1638091558510669

Abstract Details

2021, Doctor of Philosophy, Ohio State University, Anthropology.
Identifying dietary signals in extant primate dental features has significant implications for inferring diet in fossil primates (including hominins) and can reveal potential disconnects between extant primates’ dental features and current diets. Consumption of hard foods (durophagy) in modern primates has been linked to features that protect teeth against cracks and crack propagation: large tooth size, low-crowned, “bunodont” teeth, thick enamel, and unevenly distributed enamel. In broad terms, this dissertation seeks to systematically test associations between hard object feeding and various enamel features (tooth size, tooth shape, and enamel thickness distribution) in both premolars and molars across a range of primates, taking into account phylogeny. In so doing, this dissertation provides insight into how closely these features track the evolution of durophagy. Most previous studies have been limited to a small number of measurements taken on molars from a limited number of species, without taking into account phylogenetic relationships. Primate groups are closely related and share an evolutionary history and thus there is a chance that the traits associated with durophagy may have more to do with phylogenetic history than with the novel adoption of durophagous diets within a clade. The ultimate aim of this dissertation is to elucidate whether (or not) there are dental features that are consistently associated with durophagy that might allow paleoanthropologists to reliably infer the evolution of durophagous behavior in the past. Given the noted evolvability of enamel thickness, variables associated with enamel thickness were hypothesized to be most frequently associated with durophagy. Tooth size, cusp shape, and enamel distribution were recorded on more than 600 histological and virtual 2D slices of premolars and molars from primates, fossil hominins, and modern human populations. A protocol for accurately reconstructing worn enamel cusp tips was created and employed in Chapter 2. There were no specific measurements of tooth size, tooth shape, or enamel distribution that were unique to durophagous species or ubiquitous across durophagous species, suggesting that no one trait, or combination of traits, can be reliably used to diagnose durophagy. However, the upper and lower molars (Chapter 3) and upper premolars (Chapter 4) of durophagous taxa all showed some occlusal enamel thickening, concentrating enamel across the lateral walls, cusp tips, and/or occlusal basin, with a steep drop-off in enamel toward the cervix. This finding supports the prediction that enamel thickness variation would be most closely associated with durophagy. The strength of this association and the specific measurements that support the trend varied by tooth type and species. Aspects of tooth shape and tooth size were infrequently found in in specific association with durophagy, likely because those features were found to be closely tied to phylogenetic history. Finally, this dissertation evaluates how the dental features associated with durophagy found here can be used to gain insight into dietary change in the fossil record. A recent study found that, when comparing P. robustus crania from two time periods, later P. robustus exhibited dietary adaptations that increased bite force in association with a climactic drying period that likely introduced more mechanically challenging foods into the diet. The dissertation study sample included P. robustus specimens spanning ~1 million years. An evaluation of trends in this sample revealed significant shifts in P. robustus molar and premolar dental form across time, all in ways that would be consistent with increased durophagy. Upper fourth premolars showed the most dramatic change across time, increasing in size, strength, AET, and occlusal enamel thickness and decreasing in proportional lateral wall linear measurements. This suggests that teeth can change over short evolutionary time spans in response to environmental and dietary shifts and that the magnitude of change may vary by tooth type.
Debbie Guatelli-Steinberg (Advisor)
Mark Hubbe (Committee Member)
Patrick Mahoney (Committee Member)
W. Scott McGraw (Committee Member)
Gary T. Schwartz (Committee Member)
515 p.
Evolution and Development; Physical Anthropology
durophagy; hard-object feeding; hominins; enamel; enamel thickness; evolution; Paranthropus robustus; Homo naledi; Cercocebus; Pongo; catarrhine; premolar; molar; durophagous; hominin; Homo; Australopithecus; Macaca; Pan; Gorilla; Cercopithecus; Papio;

Recommended Citations

Citations

  • O'Hara, M. C. (2021). Features of catarrhine posterior dental crowns associated with durophagy: Implications for fossil hominins [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1638091558510669

    APA Style (7th edition)

  • O'Hara, Mackie. Features of catarrhine posterior dental crowns associated with durophagy: Implications for fossil hominins. 2021. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1638091558510669.

    MLA Style (8th edition)

  • O'Hara, Mackie. "Features of catarrhine posterior dental crowns associated with durophagy: Implications for fossil hominins." Doctoral dissertation, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1638091558510669

    Chicago Manual of Style (17th edition)

osu1638091558510669
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This open access ETD is published by The Ohio State University and OhioLINK.