Research in hominoid cranial ontogeny has provided significant insight into the similarities and differences between apes and humans. Additionally, questions about within-species variability, allometry, and levels of sexual dimorphism in fossil hominoids are commonly addressed using the extant great apes as a comparative framework. However, this model is incomplete without the addition of the lesser apes, gibbons and siamangs. This analysis completes the hominoid record of cranial ontogeny with the addition of the Hylobatidae, and provides a full description of their cranial ontogeny and adult variation. Three-dimensional coordinates of 145 landmarks and 313 semilandmarks were measured on CT and surface scans from an ontogenetic sample of hominoid crania, comprising Pan, Gorilla, Pongo, Hylobates, and Symphalangus, with a cercopithecoid out-group, Colobus. After Procrustes superimposition, principal component analyses were computed in shape space. Regressions of shape coordinates on centroid size were used to assess within-group ontogenetic and static allometric trajectories. Results indicate that the shape changes during ontogeny in gibbons are similar to the shape changes previously reported for great apes. Genus-specific differences are already observable early in ontogeny, and the subsequent ontogenetic trajectories are almost parallel. Sexual dimorphism for both shape and size is found in Symphalangus adults, which was previously unobserved. Analysis of all taxa in the sample shows nearly parallel ontogenetic trajectories within the Hominoidea, which is consistent with previous studies. With the addition of hylobatids and Colobus, this analysis demonstrates that cranial ontogeny is highly conserved in the Catarrhini. Given the existence of this basic catarrhine growth trajectory, it should be possible in the future to predict fossil taxa morphologies at any stage of growth.

Research in hominoid cranial ontogeny has provided significant insight into the similarities and differences between apes and humans. Additionally, questions about within-species variability, allometry, and levels of sexual dimorphism in fossil hominoids are commonly addressed using the extant great apes as a comparative framework. However, this model is incomplete without the addition of the lesser apes, gibbons and siamangs. This analysis completes the hominoid record of cranial ontogeny with the addition of the Hylobatidae, and provides a full description of their cranial ontogeny and adult variation. Three-dimensional coordinates of 145 landmarks and 313 semilandmarks were measured on CT and surface scans from an ontogenetic sample of hominoid crania, comprising Pan, Gorilla, Pongo, Hylobates, and Symphalangus, with a cercopithecoid out-group, Colobus. After Procrustes superimposition, principal component analyses were computed in shape space. Regressions of shape coordinates on centroid size were used to assess within-group ontogenetic and static allometric trajectories. Results indicate that the shape changes during ontogeny in gibbons are similar to the shape changes previously reported for great apes. Genus-specific differences are already observable early in ontogeny, and the subsequent ontogenetic trajectories are almost parallel. Sexual dimorphism for both shape and size is found in Symphalangus adults, which was previously unobserved. Analysis of all taxa in the sample shows nearly parallel ontogenetic trajectories within the Hominoidea, which is consistent with previous studies. With the addition of hylobatids and Colobus, this analysis demonstrates that cranial ontogeny is highly conserved in the Catarrhini. Given the existence of this basic catarrhine growth trajectory, it should be possible in the future to predict fossil taxa morphologies at any stage of growth.

No description available.

The origin and diversification of great apes and humans is among the most researched and debated series of events in the evolutionary history of the Primates. A fundamental part of understanding these events involves reconstructing paleoenvironmental and paleogeographic patterns in the Eurasian Miocene; a time period and geographic expanse rich in evidence of lineage origins and dispersals of numerous mammalian lineages, including apes. Traditionally, the geographic origin of the African ape and human lineage is considered to have occurred in Africa, however, an alternative hypothesis favouring a Eurasian origin has been proposed. This hypothesis suggests that that after an initial dispersal from Africa to Eurasia at ~17Ma and subsequent radiation from Spain to China, fossil apes disperse back to Africa at least once and found the African ape and human lineage in the late Miocene. The purpose of this study is to test the Eurasian origin hypothesis through the analysis of spatial and temporal patterns of distribution, in situ evolution, interprovincial and intercontinental dispersals of Eurasian terrestrial mammals in response to environmental factors. Using the NOW and Paleobiology databases, together with data collected through survey and excavation of middle and late Miocene vertebrate localities in Hungary and Romania, taphonomic bias and sampling completeness of Eurasian faunas are assessed. Previous bioprovincial zonations of Europe and Western Asia are evaluated and modified based on statistical analysis of Eurasian faunas and consideration of geophysical, climatic and eustatic events. Within these bioprovinces, occurrences of in situ evolution and directionality of dispersals of land mammals are used as a framework to address and evaluate these same processes in Eurasian apes. The results of this analysis support previous hypotheses regarding first occurrences and phyletic relations among Eurasian apes and propose new ideas regarding the relations of these taxa to previously known and newly discovered late Miocene African apes. Together with analysis of environmental data, Eurasian mammals support the hypothesis that the descendant of a Eurasian ape dispersed to Africa in the early late Miocene (top of MN7/8 or base of MN9), however the question of whether this taxon founded the African ape and human lineage remains equivocal.

The origin and diversification of great apes and humans is among the most researched and debated series of events in the evolutionary history of the Primates. A fundamental part of understanding these events involves reconstructing paleoenvironmental and paleogeographic patterns in the Eurasian Miocene; a time period and geographic expanse rich in evidence of lineage origins and dispersals of numerous mammalian lineages, including apes. Traditionally, the geographic origin of the African ape and human lineage is considered to have occurred in Africa, however, an alternative hypothesis favouring a Eurasian origin has been proposed. This hypothesis suggests that that after an initial dispersal from Africa to Eurasia at ~17Ma and subsequent radiation from Spain to China, fossil apes disperse back to Africa at least once and found the African ape and human lineage in the late Miocene. The purpose of this study is to test the Eurasian origin hypothesis through the analysis of spatial and temporal patterns of distribution, in situ evolution, interprovincial and intercontinental dispersals of Eurasian terrestrial mammals in response to environmental factors. Using the NOW and Paleobiology databases, together with data collected through survey and excavation of middle and late Miocene vertebrate localities in Hungary and Romania, taphonomic bias and sampling completeness of Eurasian faunas are assessed. Previous bioprovincial zonations of Europe and Western Asia are evaluated and modified based on statistical analysis of Eurasian faunas and consideration of geophysical, climatic and eustatic events. Within these bioprovinces, occurrences of in situ evolution and directionality of dispersals of land mammals are used as a framework to address and evaluate these same processes in Eurasian apes. The results of this analysis support previous hypotheses regarding first occurrences and phyletic relations among Eurasian apes and propose new ideas regarding the relations of these taxa to previously known and newly discovered late Miocene African apes. Together with analysis of environmental data, Eurasian mammals support the hypothesis that the descendant of a Eurasian ape dispersed to Africa in the early late Miocene (top of MN7/8 or base of MN9), however the question of whether this taxon founded the African ape and human lineage remains equivocal.

Many studies have examined pelvic sexual dimorphism and its functional implications in linear analyses, but few have used three-dimensional (3D) methods, which are ideal for complex structures such as the pelvis. This study examines human and ape os coxae using 3D geometric morphometrics (GM) to determine if patterns of sexual dimorphism relate to obstetrical and/or biomechanical requirements. Twenty-five 3D landmarks were collected on 35 human and 116 hominoid os coxae. Generalized Procrustes and principal component analyses were performed on combined and sex-specific species samples. Tests of male and female human os coxae demonstrate dimorphism in several pelvic traits related to increasing birth canal dimensions in females; females have a wider subpubic angle and greater sciatic notch than males, as well as a short ischial spine. Hominoids, however, did not exhibit sexual dimorphism in pelvic shape. These results confirm previous studies showing that human pelvic shape dimorphism is related to the obstetrical requirements of birthing a large fetus, rather than sexual dimorphism in locomotor biomechanics. Future 3D GM research on other primate species that have large neonates relative to maternal size may determine whether the primate pelvis exhibits similar patterns of response to obstetrical selection pressures as in humans.

No description available.

No description available.

All living hominoids are characterized by taillessness and adaptations to orthograde (upright) trunk posture. Accordingly, these features have importance for our understanding of ape origins, evolutionary relationships and positional behaviors. Despite extensive study of the hominoid postcranial skeleton, researchers continue to face difficulty identifying taillessness and orthogrady from fossil material. In part, difficulties persist because although the Miocene fossil record indicates that the evolution of tail loss and orthogrady was decoupled, previous research has focused primarily on how the skeletal anatomy of extinct apes resembles that of living apes, in which these traits appear in conjunction. The remarkable diversity in tail lengths and positional behaviors exhibited by other mammals presents a valuable opportunity to employ the strength of the comparative method for testing functional hypotheses. The goal of this dissertation is to identify anatomical correlates of tail length and positional behaviors from sacral and caudal vertebral morphology among primates and other mammals in three studies. The first study examines the relationship between trabecular structure in the first sacral vertebra and positional behaviors (N= 78 primates). The second study quantifies aspects of internal (N=78 primates) and external (N= 472 mammals) sacral anatomy for correlates of relative tail length. The third study evaluates the functional morphology of caudal vertebrae among nonprehensile-tailed primates and other mammals that vary in relative tail length, offering additional insight into the anatomy associated with tail loss (N=333). The relationship between trabecular structure in the proximal sacrum and positional behaviors among living primates is somewhat unclear. Some trabecular parameters in the distal sacrum appear to have a relationship with tail length. Results support the functional links between previously and newly defined metrics from the external morphology of sacra and caudal vertebrae, and relative tail length, among primates and other mammals. Identified anatomical correlates from the extant primate sample are used to reconstruct the tail lengths of extinct primates. From the sacral data, Proconsul is reconstructed as tailless, Archaeolemur likely possessed a long tail, and Palaeopropithecus, Megaladapis and Epipliopithecus had short tails. From the caudal vertebrae data, Archaeolemur is reconstructed as possessing a long tail and Palaeopropithecus is reconstructed as having a short tail. / text

No description available.