ORCID Profile
0000-0002-6677-9390
Current Organisation
La Trobe University
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Publisher: Wiley
Date: 27-08-2012
Publisher: Elsevier BV
Date: 12-2006
DOI: 10.1016/J.JHEVOL.2006.07.008
Abstract: When dental morphological variation within extant species is used as a guideline to partition variation within fossil s les into species, the underlying assumption is that fossil species are equivalent to extant species. This is the case despite the fact that dental morphology, which is commonly used to differentiate fossil species, is rarely used to differentiate extant species. Aspects of external morphology, ecology, behavior, breeding patterns, and molecular structure that are used to delineate living species are generally not available for fossils. In this paper, the utility of dental evidence for sorting fossil s les into species is evaluated by testing whether molar occlusal morphology is capable of sorting populations of Pan into the species and subspecies already well-established by nondental evidence. The dentitions of 341 chimpanzee in iduals, s led from regions throughout equatorial Africa, were sorted into 16 populations using rivers to demarcate the boundaries between populations. Digital-imaging software was used to measure 15 traits on the occlusal surface of each upper molar and 19 on each lower molar. After applying size adjustments, size-transformed and untransformed variables were subjected to discriminant analysis, with separate analyses carried out for each molar type. Results indicate that populations of Pan troglodytes and Pan paniscus are well differentiated at all molar positions. Populations of P. t. verus are distinct from other populations of P. troglodytes. Populations of P. t. troglodytes and P. t. schweinfurthii show close dental similarity. A distinct population is recognized at the Nigeria-Cameroon border, indicating the presence of P. t. vellerosus. The concordance between the patterns of ersity recognized by this study and other molecular and nonmolecular studies indicates that paleontological species that are similar to species of Pan in terms of size and patterns of ersification may be differentiated using molar morphology.
Publisher: PeerJ
Date: 23-05-2019
DOI: 10.7717/PEERJ.6990
Abstract: Worn teeth pose a major limitation to researchers in the fields of extinct and extant hominoid systematics because they lack clearly identifiable anatomical landmarks needed to take measurements on the crown enamel surface and are typically discarded from a study. This is particularly detrimental when s le sizes for some groups are already characteristically low, if there is an imbalance between s les representing populations, sexes or dietary strategies, or if the worn teeth in question are type specimens of fossil species or other key specimens. This study proposes a methodology based predominantly on mathematically-derived landmarks for measuring size and shape features of molars, irrespective of wear. With 110 specimens of lower second molars from five species of extant hominoids ( Pan troglodytes, P. paniscus, Gorilla gorilla, G. beringei, Homo sapiens ), n ≥ 20 per species, n ≥ 10 per subspecies, good species separation in morphospace is achieved in a principal components analysis. Classification accuracy in a discriminant function analysis is 96.4% at the species level and 88.2% at the subspecies level (92.7% and 79.1%, respectively, on cross-validation). The classification accuracy compares favorably to that achieved by anatomically-derived measurements based on published research (94% and 84% at the species and subspecies level respectively 91% and 76% on cross-validation). The mathematical landmarking methodology is rapid and uncomplicated. The results support the use of mathematical landmarks to enable the inclusion of worn molar teeth in dental studies so as to maximize s le sizes and restore balance between populations and/or sexes in hominoid systematic studies.
Publisher: No publisher found
Date: 2015
Publisher: Elsevier BV
Date: 06-2010
Publisher: No publisher found
Date: 2015
Publisher: Parantez Teknologji Ltd
Date: 15-06-2010
Publisher: Springer Science and Business Media LLC
Date: 23-11-2013
Publisher: Wiley
Date: 10-08-2020
DOI: 10.1002/AJPA.24120
Publisher: Wiley
Date: 08-03-2011
DOI: 10.1002/CA.21157
Publisher: Wiley
Date: 05-02-2018
DOI: 10.1002/AJPA.23412
Abstract: The arrival of the Huns into Europe in the fourth century AD increased the occurrence of intentional cranial modification among European nomads. It has been postulated that the Huns used a two-bandage cranial binding technique to differentiate themselves from surrounding nomadic groups, including those from Georgia. This study examines this hypothesis by comparing Migration Period (4th to 7th century AD) juvenile crania, which retain strong impressions of bindings, with adult modified crania from Hungary and Georgia. Twelve surface landmarks and 251 semi-landmarks were used to study ontogenetic trajectories in 9 juvenile and 16 adult modified skulls from 8 Hungarian sites and 21 adult skulls from two Georgian sites. Generalized Procrustes analysis, linear regression of Procrutes distance on dental age and log centroid size, and warping the principal components (PCs) in shape space helped to identify cranial shape changes. The PCs provide significant separation of the juvenile and adult groups from Georgia and Hungary. Variation in modified cranial shape was limited in Hungary compared to Georgia. There was stronger correlation between juvenile and adult modified cranial shape in Hungary than in Georgia. Warping along the first axis reveals the trajectory from marked flattening of the frontal and occipital regions in juveniles to diminished flattening in the same regions in adult crania, corresponding with one binding. Another depression extending from the post-bregmatic region to the temporal region, similarly strong in juveniles but diminishing in adults, marks the second binding. Hungarian crania were modified with two bindings with limited shape variation, whereas the Georgian crania had greater variation in shape being also modified with antero-posterior bindings. The findings from this study alongside contemporary historical sources help to understand the role of intentional cranial modification as a mark of social identity among nomads in the Migration Period of Europe.
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.JHEVOL.2010.01.009
Abstract: Gorilla patterns of variation have great relevance for studies of human evolution. In this study, molar morphometrics were used to evaluate patterns of geographic variation in gorillas. Dental specimens of 323 adult in iduals, drawn from the current distribution of gorillas in equatorial Africa were ided into 14 populations. Discriminant analyses and Mahalanobis distances were used to study population structure. Results reveal that: 1) the West and East African gorillas form distinct clusters, 2) the Cross River gorillas are well separated from the rest of the western populations, 3) gorillas from the Virunga mountains and the Bwindi Forest can be differentiated from the lowland gorillas of Utu and Mwenga-Fizi, 4) the Tshiaberimu gorillas are distinct from other eastern gorillas, and the Kahuzi-Biega gorillas are affiliated with them. These findings provide support for a species distinction between Gorilla gorilla and Gorilla beringei, with subspecies G. g. diehli, G. g. gorilla, G. b. graueri, G. b. beringei, and possibly, G. b. rex-pygmaeorum. Clear correspondence between dental and other patterns of taxonomic ersity demonstrates that dental data reveal underlying genetic patterns of differentiation. Dental distances increased predictably with altitude but not with geographic distances, indicating that altitudinal segregation explains gorilla patterns of population ergence better than isolation-by-distance. The phylogeographic pattern of gorilla dental metric variation supports the idea that Plio-Pleistocene climatic fluctuations and local mountain building activity in Africa affected gorilla phylogeography. I propose that West Africa comprised the historic center of gorilla distribution and experienced drift-gene flow equilibrium, whereas Nigeria and East Africa were at the periphery, where climatic instability and altitudinal variation promoted drift and genetic differentiation. This understanding of gorilla population structure has implications for gorilla conservation, and for understanding the distribution of sympatric chimpanzees and Plio-Pleistocene hominins.
Publisher: Wiley
Date: 1994
Publisher: Elsevier BV
Date: 05-2019
Publisher: No publisher found
Date: 2015
Publisher: Wiley
Date: 03-2006
DOI: 10.1002/AJPA.20246
Abstract: The morphology of the anterior dentition has received scant attention for purposes of taxonomic discrimination. Recently, however, lingual incisor morphology was used in differentiating several Miocene ape species and genera. This paper assesses the utility of this morphology for taxonomic discrimination by examining the nature and patterns of variation in lingual incisor morphology in extensive s les of modern chimpanzees, gorillas, orangutans, and gibbons. This paper documents discrete morphological traits on the lingual side of incisors. Trait frequencies are used in univariate and multivariate analyses to examine the apportionment of variation in species, subspecies, and populations. A correlation between lingual incisor traits, tooth dimensions, and sex attempts to determine if such factors affect the manifestation of traits. Finally, the findings are applied to understanding patterns of variation in the Miocene hominids. The study demonstrates that: 1) lingual incisor morphology differs substantially between the hylobatids and great apes 2) variation in incisor traits is high within species, and most of it is found within local populations and 3) incisor traits do not correlate significantly with incisor dimensions or sex. Species and to some extent subspecies of extant hominoids can be differentiated statistically using lingual incisor traits, but the frequency of traits such as continuous or discontinuous cingulum, or the presence or absence of pillars, differentiates them. Given this pattern of variation, I argue that it is necessary to assume and document similar patterns of variation in Miocene apes before incisor morphology is used for differentiating taxa.
Publisher: Wiley
Date: 10-2004
Publisher: Springer Science and Business Media LLC
Date: 23-04-2019
Publisher: Public Library of Science (PLoS)
Date: 08-07-2015
Publisher: Springer Netherlands
Date: 2007
Publisher: No publisher found
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 10-2016
Publisher: Wiley
Date: 19-11-2022
DOI: 10.1111/ADJ.12887
Abstract: The prevalence of radicular defects after root canal instrumentation is unresolved. This study used micro-CT to assess the relationship between the formation of radicular defects and chemo-mechanical instrumentation in a cadaver model. Maxillary and mandibular molars (n = 24) were sectioned from cadaver specimens as a tissue block containing the teeth, alveolar bone and attached mucogingival tissues. After a baseline micro-CT scan (13.45 μm), the specimens were distributed into 3 groups (n = 8 molars): Reciproc Overall, 16 pre-existing radicular defects were identified in 12 of the 24 molars (50%). Most of these were cemental tears (87.5%), and not true dentinal microcracks. New dentinal microcracks were observed in the post-operative micro-CT scans of only 3 canals (3.9% 3/77). However, only one of these defects was found to be present histologically. Within the limitations of the study, chemo-mechanical instrumentation did not routinely promote the formation of radicular defects.
Publisher: Public Library of Science (PLoS)
Date: 02-02-2017
Location: United States of America
Start Date: 2015
End Date: 2016
Funder: University of Melbourne
View Funded ActivityStart Date: 1999
End Date: 2002
Funder: National Science Foundation
View Funded ActivityStart Date: 2014
End Date: 2014
Funder: University of Melbourne
View Funded ActivityStart Date: 1998
End Date: 2001
Funder: Wenner-Gren Foundation
View Funded ActivityStart Date: 1998
End Date: 2001
Funder: Leakey Foundation
View Funded ActivityStart Date: 2012
End Date: 2014
Funder: Leakey Foundation
View Funded Activity