| dc.identifier.uri | http://hdl.handle.net/11401/76293 | |
| dc.description.sponsorship | This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. | en_US |
| dc.format | Monograph | |
| dc.format.medium | Electronic Resource | en_US |
| dc.language.iso | en_US | |
| dc.publisher | The Graduate School, Stony Brook University: Stony Brook, NY. | |
| dc.type | Dissertation | |
| dcterms.abstract | New imaging technologies are rapidly changing the nature of morphological data by making possible the creation and sharing of large samples of digital scan data, creating a need for high-throughput morphometric methods. A promising example of this can be found in morphological topographic analysis, a suite of algorithms for describing surface shape properties. Topographic methods have been used effectively to address dietary functional morphology of molars in a number of mammal radiations. These methods may be also useful for answering other questions concerning molar shape. Empirical models of mouse molar morphogenesis include predictions concerning molar shape variation that could apply to many mammals. Testing these predictions in primate species may allow consideration of developmental mechanisms of evolutionary change and, relatedly, evolutionary change of developmental mechanisms. This dissertation seeks (1) to develop new tools for deriving shape properties from morphological data using morphological topographic analysis, (2) to better understand how to apply topographic methods to investigate morphology, (3) to document morphological topography of lower second molars of cercopithecoids in the context of feeding behavior, phylogenetic relationships, allometry, and tooth wear; and (4) to test developmental hypotheses concerning molar size proportions and shape variability on cercopithecoid molar teeth. Chapter 2 discusses the production of morphological topographic data from anatomical specimens. An application for morphological topographic analysis is introduced. This application, MorphoTester, implements three common topographic metrics: Dirichlet normal energy (DNE, quantifying bending or curvature), relief index (RFI, quantifying relief), and orientation patch count rotated (OPCR, quantifying complexity). The efficacy of the OPCR algorithm here is first assessed because of differences between this method and previous implementations. Topography is then quantified from simple geometric objects to better understand how topography reflects shape. Simple geometric objects simplistically mimic addition of cusps and increases in cusp height. Results suggest that complexity reflects surface features number, and that curvature and relief are both correlated with surface feature shape and number. Surface curvature is more sensitive than relief to interactions between these two factors. Effects of mesh preparation – surface cropping, simplification, smoothing, and rotation – on quantified topography are then tested using a cercopithecoid M2 test sample. Occlusal basin cropping maximizes interspecific topographic variability in this sample. Simplification and smoothing both modify surface shape, and topographic metrics change accordingly. DNE and OPCR change in similar ways, befitting their nature as sums reflecting relatively local aspects of shape. RFI is more conservative to simplification and smoothing as a ratio of two measures which themselves change with simplification and smoothing. Surface rotation changes RFI and OPCR in complex ways, but little change is observed within 5 degrees of rotation. Overall, results indicate that surface preparation is a process of abstraction, and decisions concerning this process must be made while cognizant of the specific sample and research questions involved. Chapter 3 applies topographic metrics to a large sample of M2s belonging to a diverse collection of extant cercopithecoid species in order to investigate dietary functional morphology in this radiation. Species are sorted into one of four dietary categories based on food mechanical properties: durophagy, soft-object feeding, moderate elasticophagy, and extreme elasticophagy. The last category includes only Theropithecus gelada, which habitually consumes grass components that can be much tougher than the toughest components of other cercopithecoid diets. Possible allometric influences on DNE, RFI, and OPCR are tested using species body mass and specimen M2 area as body-size proxies. Results suggest that topographic metrics do not scale allometrically in this sample. Topographic metrics are then tested to determine whether they vary significantly between dietary categories. Results of standard statistical analyses indicate that DNE, RFI, and OPCR all vary significantly, but phylogenetically-informed analyses with maximal phylogenetic signal show a lack of significance for OPCR. Overall, cercopithecoid M2s vary most strongly in surface relief. In addition, predictive models of diet achieve accuracy ratings well above chance but lower than has been observed for other primate radiations. These facts probably relate to cercopithecoid bilophodont molar configuration, with diet-related variation primarily arising through changes in relief of molar cusps and crests. Comparatively, Theropithecus gelada M2s exhibit similar relief to folivorous colobines but significantly greater curvature, reflecting high columnar cusps and wear-induced enamel bands. This unusual topographic profile is a novel among cercopithecoids and likely represents adaptations to consuming highly fibrous grass components. The analyses above were performed with a sample of relatively less worn M2s. A second sample with more variably worn M2s was used to test topographic change across wear. Relief index was used as a wear proxy, and surface curvature and complexity were regressed on relief. Curvature does not seem to be related to relief as a wear proxy, but there is evidence to suggest that M2 complexity increases as relief decreases. As both relief and complexity are functionally related, this may represent a compensatory balance that helps maintain tooth function through wear. Chapter 4 tests whether cercopithecoid molar size and shape relationships conform to predictions from models of molar morphogenesis. Empirical studies of mouse molar development have identified several patterning cascades whereby earlier-developing molar teeth control the size, spacing, and shape of subsequent molars and earlier-developing cusps play a similar role for later-developing cusps. A sample of mesiodistal molar lengths from the literature is used to test the prediction that M3 size relative to M1 size regressed on M2 size relative to M1 size should produce a regression with a slope of 2.0 and an intercept of -1.0, as predicted by the inhibitory cascade model of molar size proportions. Colobines and papionins conform to these expectations, but cercopithecins do not. While in colobines and papionins M3 is larger than M2, at least partially because of M3 hypoconulids, cercopithecins lack M3 hypoconulids and M3 is smaller than M2 in this clade. This is interpreted to reflect an evolutionary modification to a morphogenetic termination character, causing cercopithecin M3s to cease development earlier and resulting in a lack of M3 hypoconulid. But because for all clades M2 is larger than M1, it is suggested that morphogenetic processes in all cercopithecoids exhibit an activator/inhibitor balance where activator factors are stronger than inhibitors. While the inhibitory cascade model includes predictions concerning molar size proportions, the patterning cascade model predicts that later-developing molars and molar cusps should be more variable in shape than earlier-developing molars or cusps. Morphological topographic analysis and geometric morphometric techniques are applied to M1s, M2s, and M3s of Colobus and Cercopithecus species to test this prediction between molars. Topographic analysis and geometric morphometrics using cusp-tip landmarks of M3s belonging to 4 species of cercopithecoids are used to test the prediction between M3 cusps. Geometric morphometric results indicate that more posterior molars are more variable in shape as expected. More posterior M3 cusps are also more variable in position than more anterior M3 cusps, both within species and between species. Comparatively, topographic analyses may be less well suited to quantifying levels of morphological variation. Cusp-tip landmarks were also used to test the hypothesis that hypoconulid position can be predicted from non-hypoconulid cusp relationships, and there is some evidence to suggest that contraction of posterior non-hypoconulid cusps relative to anterior cusps is correlated with a less prominent hypoconulid. In general, results demonstrate interrelatedness of molar morphology at various levels, hinting at the presence of presumably ancient mammalian morphogenetic processes combined with derived modifications to developmental processes resulting in morphological change. This dissertation develops tools for high-throughput morphometrics, and applies these tools to address functional and developmental influences on mandibular molar shape in extant cercopithecoid primates. Taken together, results indicate there is still much to be learned from primate molar morphology. The changing landscape of morphological analysis holds great promise for future insights if our analytical methods are adapted to the large and diverse samples of digital data that increasingly make up the selective environment of research. | |
| dcterms.abstract | New imaging technologies are rapidly changing the nature of morphological data by making possible the creation and sharing of large samples of digital scan data, creating a need for high-throughput morphometric methods. A promising example of this can be found in morphological topographic analysis, a suite of algorithms for describing surface shape properties. Topographic methods have been used effectively to address dietary functional morphology of molars in a number of mammal radiations. These methods may be also useful for answering other questions concerning molar shape. Empirical models of mouse molar morphogenesis include predictions concerning molar shape variation that could apply to many mammals. Testing these predictions in primate species may allow consideration of developmental mechanisms of evolutionary change and, relatedly, evolutionary change of developmental mechanisms. This dissertation seeks (1) to develop new tools for deriving shape properties from morphological data using morphological topographic analysis, (2) to better understand how to apply topographic methods to investigate morphology, (3) to document morphological topography of lower second molars of cercopithecoids in the context of feeding behavior, phylogenetic relationships, allometry, and tooth wear; and (4) to test developmental hypotheses concerning molar size proportions and shape variability on cercopithecoid molar teeth. Chapter 2 discusses the production of morphological topographic data from anatomical specimens. An application for morphological topographic analysis is introduced. This application, MorphoTester, implements three common topographic metrics: Dirichlet normal energy (DNE, quantifying bending or curvature), relief index (RFI, quantifying relief), and orientation patch count rotated (OPCR, quantifying complexity). The efficacy of the OPCR algorithm here is first assessed because of differences between this method and previous implementations. Topography is then quantified from simple geometric objects to better understand how topography reflects shape. Simple geometric objects simplistically mimic addition of cusps and increases in cusp height. Results suggest that complexity reflects surface features number, and that curvature and relief are both correlated with surface feature shape and number. Surface curvature is more sensitive than relief to interactions between these two factors. Effects of mesh preparation – surface cropping, simplification, smoothing, and rotation – on quantified topography are then tested using a cercopithecoid M2 test sample. Occlusal basin cropping maximizes interspecific topographic variability in this sample. Simplification and smoothing both modify surface shape, and topographic metrics change accordingly. DNE and OPCR change in similar ways, befitting their nature as sums reflecting relatively local aspects of shape. RFI is more conservative to simplification and smoothing as a ratio of two measures which themselves change with simplification and smoothing. Surface rotation changes RFI and OPCR in complex ways, but little change is observed within 5 degrees of rotation. Overall, results indicate that surface preparation is a process of abstraction, and decisions concerning this process must be made while cognizant of the specific sample and research questions involved. Chapter 3 applies topographic metrics to a large sample of M2s belonging to a diverse collection of extant cercopithecoid species in order to investigate dietary functional morphology in this radiation. Species are sorted into one of four dietary categories based on food mechanical properties: durophagy, soft-object feeding, moderate elasticophagy, and extreme elasticophagy. The last category includes only Theropithecus gelada, which habitually consumes grass components that can be much tougher than the toughest components of other cercopithecoid diets. Possible allometric influences on DNE, RFI, and OPCR are tested using species body mass and specimen M2 area as body-size proxies. Results suggest that topographic metrics do not scale allometrically in this sample. Topographic metrics are then tested to determine whether they vary significantly between dietary categories. Results of standard statistical analyses indicate that DNE, RFI, and OPCR all vary significantly, but phylogenetically-informed analyses with maximal phylogenetic signal show a lack of significance for OPCR. Overall, cercopithecoid M2s vary most strongly in surface relief. In addition, predictive models of diet achieve accuracy ratings well above chance but lower than has been observed for other primate radiations. These facts probably relate to cercopithecoid bilophodont molar configuration, with diet-related variation primarily arising through changes in relief of molar cusps and crests. Comparatively, Theropithecus gelada M2s exhibit similar relief to folivorous colobines but significantly greater curvature, reflecting high columnar cusps and wear-induced enamel bands. This unusual topographic profile is a novel among cercopithecoids and likely represents adaptations to consuming highly fibrous grass components. The analyses above were performed with a sample of relatively less worn M2s. A second sample with more variably worn M2s was used to test topographic change across wear. Relief index was used as a wear proxy, and surface curvature and complexity were regressed on relief. Curvature does not seem to be related to relief as a wear proxy, but there is evidence to suggest that M2 complexity increases as relief decreases. As both relief and complexity are functionally related, this may represent a compensatory balance that helps maintain tooth function through wear. Chapter 4 tests whether cercopithecoid molar size and shape relationships conform to predictions from models of molar morphogenesis. Empirical studies of mouse molar development have identified several patterning cascades whereby earlier-developing molar teeth control the size, spacing, and shape of subsequent molars and earlier-developing cusps play a similar role for later-developing cusps. A sample of mesiodistal molar lengths from the literature is used to test the prediction that M3 size relative to M1 size regressed on M2 size relative to M1 size should produce a regression with a slope of 2.0 and an intercept of -1.0, as predicted by the inhibitory cascade model of molar size proportions. Colobines and papionins conform to these expectations, but cercopithecins do not. While in colobines and papionins M3 is larger than M2, at least partially because of M3 hypoconulids, cercopithecins lack M3 hypoconulids and M3 is smaller than M2 in this clade. This is interpreted to reflect an evolutionary modification to a morphogenetic termination character, causing cercopithecin M3s to cease development earlier and resulting in a lack of M3 hypoconulid. But because for all clades M2 is larger than M1, it is suggested that morphogenetic processes in all cercopithecoids exhibit an activator/inhibitor balance where activator factors are stronger than inhibitors. While the inhibitory cascade model includes predictions concerning molar size proportions, the patterning cascade model predicts that later-developing molars and molar cusps should be more variable in shape than earlier-developing molars or cusps. Morphological topographic analysis and geometric morphometric techniques are applied to M1s, M2s, and M3s of Colobus and Cercopithecus species to test this prediction between molars. Topographic analysis and geometric morphometrics using cusp-tip landmarks of M3s belonging to 4 species of cercopithecoids are used to test the prediction between M3 cusps. Geometric morphometric results indicate that more posterior molars are more variable in shape as expected. More posterior M3 cusps are also more variable in position than more anterior M3 cusps, both within species and between species. Comparatively, topographic analyses may be less well suited to quantifying levels of morphological variation. Cusp-tip landmarks were also used to test the hypothesis that hypoconulid position can be predicted from non-hypoconulid cusp relationships, and there is some evidence to suggest that contraction of posterior non-hypoconulid cusps relative to anterior cusps is correlated with a less prominent hypoconulid. In general, results demonstrate interrelatedness of molar morphology at various levels, hinting at the presence of presumably ancient mammalian morphogenetic processes combined with derived modifications to developmental processes resulting in morphological change. This dissertation develops tools for high-throughput morphometrics, and applies these tools to address functional and developmental influences on mandibular molar shape in extant cercopithecoid primates. Taken together, results indicate there is still much to be learned from primate molar morphology. The changing landscape of morphological analysis holds great promise for future insights if our analytical methods are adapted to the large and diverse samples of digital data that increasingly make up the selective environment of research. | |
| dcterms.available | 2017-09-20T16:49:58Z | |
| dcterms.contributor | Boyer, Doug M | en_US |
| dcterms.contributor | Grine, Frederick E | en_US |
| dcterms.contributor | Jernvall, Jukka | en_US |
| dcterms.contributor | Evans, Alistair R | en_US |
| dcterms.contributor | . | en_US |
| dcterms.creator | Winchester, Julia MacKay | |
| dcterms.dateAccepted | 2017-09-20T16:49:58Z | |
| dcterms.dateSubmitted | 2017-09-20T16:49:58Z | |
| dcterms.description | Department of Anthropology | en_US |
| dcterms.extent | 605 pg. | en_US |
| dcterms.format | Monograph | |
| dcterms.format | Application/PDF | en_US |
| dcterms.identifier | http://hdl.handle.net/11401/76293 | |
| dcterms.issued | 2016-12-01 | |
| dcterms.language | en_US | |
| dcterms.provenance | Made available in DSpace on 2017-09-20T16:49:58Z (GMT). No. of bitstreams: 1
Winchester_grad.sunysb_0771E_12884.pdf: 53205054 bytes, checksum: 75f1b175ec45c52812d6da3579c0123a (MD5)
Previous issue date: 1 | en |
| dcterms.publisher | The Graduate School, Stony Brook University: Stony Brook, NY. | |
| dcterms.subject | Physical anthropology -- Morphology -- Bioinformatics | |
| dcterms.subject | Cercopithecoid, Dental topographic analysis, Dirichlet normal energy, Evolutionary-developmental biology, Functional morphology, Orientation patch count rotated | |
| dcterms.title | Molar topographic shape as a system for inferring functional morphology and developmental patterning in extant cercopithecoids | |
| dcterms.type | Dissertation | |
