L'étude des caractères basicrâniens et endocraniens chez les vertébrés fossiles et actuels connait un regain d'intérêt depuis quelques années. Ces caractères bénéficient en effet d'une bonne réputation en tant que marqueurs phylogénétiques, ainsi que d'un biais taphonomique favorable à leur fossilisation. C'est pourquoi dans ce volume, la région auditive et l'oreille interne (Partie I) et l'endocrâne (Partie II) de mammifères fossiles appartenant au clade des Afrotheria ont été scannés par (micro)tomographie à rayon-X, décrits, étudiés et comparés à ceux des espèces actuelles. Il s'agit plus précisément des Afrotheria fossiles que sont les Bibymalagasia (Chapitre 1), le Macroscelididae Chambius (Chapitre 2), de nombreux Hyracoidea du Paléogène (Chapitre 3) ainsi que des Tethytheria basaux tels que le proboscidien Numidotherium, l'embrithopode Arsinoitherium et le sirénien Prorastomus (Chapitre 4). Cette étude met en lumière l'intéressant signal phylogénétique fournit par les caractères de la région auditive et de l'endocrâne, capable de soutenir certains clades moléculaires (e.g. Afroinsectivora, ‘Panelephantulus'). Elle montre aussi comment, sous certaines pressions de sélection, ces caractères peuvent converger de façon remarquable (e.g. chez les téthythères). Cette étude apporte aussi des éléments qui appuient l'hypothèse d'une origine Africaine des Afrotheria, ainsi que celle faisant de l'ancêtre commun des afrothères un mammifère plutôt ‘ongulé' que ‘insectivore'. Ces inférences fondées sur l'observation des représentants fossiles les plus anciens de ce groupe sont importants pour notre compréhension de l'origine et de la diversification des afrothères et des mammifères placentaires en général. / The study of basicranial and endocranial characters in vertebrate paleontology has recently known a regain of interest. Indeed, these characters are renowed for their phylogenetic stability and are usually easily preserved in the fossil record. Here, the auditory region (Part I) and endocranium (Part II) of some fossil representatives of the mammalian order Afrotheria have been scanned using X-ray (micro)tomography, described and compared to their modern day's counterparts. These fossil afrotheres are the Bibymalagasia (Chapter 1), the stem sengi Chambius (Chapter 2), numerous Hyracoidea (Chapter 3) and stem Tethytheria such as the proboscideans Numidotherium, the embrithopod Arsinoitherium and the sirenian Prorastomus (Chapter 4). This study highlights the strong phylogenetic signal carried by the characters of the auditory region and endocast, which could even support some molecular clades (e.g. Afroinsectivora, ‘Panelephantulus'). It also shows that convergences can occur under certain selective pressure (e.g. in Tethytheria). Finally this study brings new clues that support the hypothesis of an African origin of Afrotheria as well as that of an ‘ungulate-like' instead of ‘insectivore-like' ancestor. These inferences based on the observation of the oldest and basal-most fossil representatives of this group are crucial to understand the origin, evolution and diversification of afrotherian and placental mammals across the Cenozoic.

Objetivo: O objetivo deste trabalho foi verificar a existência de variações da morfometria de base de crânio entre indivíduos com fissura labiopalatal, com deformidade dentofacial e sem deformidade dentofacial, grupo controle. Metodologia: Três grupos de indivíduos, um grupo com deformidade dentofacial sem associação com fissura labiopalatal (DFSF), outro com fissura labiopalatal (FS), e outro grupo de pacientes sem fissura e sem deformidade (CTRL - Controle), foram elencados por meio de registros de prontuários e de imagens em DICOM (Digital Imaging Communications in Medicine) de suas tomografias computadorizadas. Por meio da identificação dos pontos cefalométricos basio (Ba), sela (S) e nasio (N), no software Dolphin Imaging 11.9, obteve-se a distância entre os pontos Ba-S (DBaS), S-N (DSN) bem como o ângulo formado entre os pontos Ba-S-N (AnGBaSN). As variáveis cefalométricas em questão foram avaliadas considerando (p<0,05). Resultados: Vinte indivíduos compuseram cada um dos grupos. Verificamos que a distância S-N (DSN) não apresentou diferença estatística entre os grupos, mas a distância Ba-S (DBaS) e o ângulo Ba-S-N (AnGBaSN) apresentaram diferenças estatísticas quando comparados os três grupos. O ângulo Ba-S-N (AnGBaSN) não apresentou diferença estatística quando comparados o grupo controle (CTRL) e o grupo de pacientes portadores de fissura labiopalatal (FS), mas apresentou diferença estatística em relação ao do grupo de pacientes com deformidades faciais sem fissuras labiopalatais (DFSF). A distância BaS (DBaS) apresentou diferença estatística entre o grupo de pacientes portadores de fissuras (FS) em relação aos outros dois grupos. Conclusão: Diferenças na morfometria da base de crânio entre indivíduos com deformidade dentofacial associada ou não a fissuras labiopalatais sugerem que valores padronizados para análises cefalométricas que envolvam tais estruturas sejam usadas com cautela. Novos padrões cefalométricos, em especial por análise 3D, são desejáveis para compensação dessas diferenças anatômicas. / Objective: The aim of this study was to verify the existence of variations of the skull base morphometry between patients with cleft lip and palate, with dentofacial deformity group and without dentofacial deformity (control group). Methodology: Three groups of patients, one group with dentofacial deformity associated without cleft lip and palate (DFSF), another with cleft lip and palate (FS), and another group of patients without cleft and without deformity (CTRL) were included by means of medical records and DICOM (Digital Imaging Communications in Medicine) images of their CT (Computed Tomography) scans. By identifying the basio (Ba), sela (S) and nasio (N) cephalometric points in the Dolphin Imaging 11.9 software, the distance between the points Ba-S (DBaS), S-N(DSN) and the angle formed between points Ba-S-N (AnGBaSN) were the variables. They were statistically evaluated by means of the p> 0.05. Results: Twenty patients were included on each group. We found that the distance S-N (DSN) is not statistically different between the groups, but the Ba-S distance (DBaS) and the Ba-S-N angle (AnGBaSN) are statistically different when compared the three groups. The Ba-S-N angle (AnGBaSN) did not present statistically different when compared to the control group (CTRL) and the group cleft lip and palate patients (FS), but presented statistical difference in relation to the group of patients with facial deformities without cleft lip and palate (DFSF). The distance BaS (DBaS) presented statistical difference between the group of patients with fissures (FS) in relation to the other two groups. Conclusion: Differences in skull base morphometry among patients with dentofacial deformity associated or not with cleft lip and palate suggest that standardized values for cephalometric analyzes involving such structures should be used with caution. New cephalometric patterns, especially by 3D analysis, are desirable to compensate for these anatomical differences.

Objetivo: O objetivo deste trabalho foi verificar a existência de variações da morfometria de base de crânio entre indivíduos com fissura labiopalatal, com deformidade dentofacial e sem deformidade dentofacial, grupo controle. Metodologia: Três grupos de indivíduos, um grupo com deformidade dentofacial sem associação com fissura labiopalatal (DFSF), outro com fissura labiopalatal (FS), e outro grupo de pacientes sem fissura e sem deformidade (CTRL - Controle), foram elencados por meio de registros de prontuários e de imagens em DICOM (Digital Imaging Communications in Medicine) de suas tomografias computadorizadas. Por meio da identificação dos pontos cefalométricos basio (Ba), sela (S) e nasio (N), no software Dolphin Imaging 11.9, obteve-se a distância entre os pontos Ba-S (DBaS), S-N (DSN) bem como o ângulo formado entre os pontos Ba-S-N (AnGBaSN). As variáveis cefalométricas em questão foram avaliadas considerando (p<0,05). Resultados: Vinte indivíduos compuseram cada um dos grupos. Verificamos que a distância S-N (DSN) não apresentou diferença estatística entre os grupos, mas a distância Ba-S (DBaS) e o ângulo Ba-S-N (AnGBaSN) apresentaram diferenças estatísticas quando comparados os três grupos. O ângulo Ba-S-N (AnGBaSN) não apresentou diferença estatística quando comparados o grupo controle (CTRL) e o grupo de pacientes portadores de fissura labiopalatal (FS), mas apresentou diferença estatística em relação ao do grupo de pacientes com deformidades faciais sem fissuras labiopalatais (DFSF). A distância BaS (DBaS) apresentou diferença estatística entre o grupo de pacientes portadores de fissuras (FS) em relação aos outros dois grupos. Conclusão: Diferenças na morfometria da base de crânio entre indivíduos com deformidade dentofacial associada ou não a fissuras labiopalatais sugerem que valores padronizados para análises cefalométricas que envolvam tais estruturas sejam usadas com cautela. Novos padrões cefalométricos, em especial por análise 3D, são desejáveis para compensação dessas diferenças anatômicas. / Objective: The aim of this study was to verify the existence of variations of the skull base morphometry between patients with cleft lip and palate, with dentofacial deformity group and without dentofacial deformity (control group). Methodology: Three groups of patients, one group with dentofacial deformity associated without cleft lip and palate (DFSF), another with cleft lip and palate (FS), and another group of patients without cleft and without deformity (CTRL) were included by means of medical records and DICOM (Digital Imaging Communications in Medicine) images of their CT (Computed Tomography) scans. By identifying the basio (Ba), sela (S) and nasio (N) cephalometric points in the Dolphin Imaging 11.9 software, the distance between the points Ba-S (DBaS), S-N(DSN) and the angle formed between points Ba-S-N (AnGBaSN) were the variables. They were statistically evaluated by means of the p> 0.05. Results: Twenty patients were included on each group. We found that the distance S-N (DSN) is not statistically different between the groups, but the Ba-S distance (DBaS) and the Ba-S-N angle (AnGBaSN) are statistically different when compared the three groups. The Ba-S-N angle (AnGBaSN) did not present statistically different when compared to the control group (CTRL) and the group cleft lip and palate patients (FS), but presented statistical difference in relation to the group of patients with facial deformities without cleft lip and palate (DFSF). The distance BaS (DBaS) presented statistical difference between the group of patients with fissures (FS) in relation to the other two groups. Conclusion: Differences in skull base morphometry among patients with dentofacial deformity associated or not with cleft lip and palate suggest that standardized values for cephalometric analyzes involving such structures should be used with caution. New cephalometric patterns, especially by 3D analysis, are desirable to compensate for these anatomical differences.

L’espèce humaine est caractérisée par une forme de locomotion bipède qui lui est propre. Toumaï, l’holotype de l’espèce Sahelanthropus tchadensis découverte au Tchad, est le plus ancien représentant connu du rameau humain. Daté de 7 millions d’années, il est très proche de la dichotomie entre ce rameau et celui des chimpanzés. C’est donc un témoin précieux des premières phases de l’évolution de la locomotion dans ce groupe. Le but de ce travail est de reconstituer le comportement locomoteur de Sahelanthropus tchadensis à partir de l’étude de la partie osseuse de son labyrinthe, organe de l’équilibre.Pour cela, les relations entre locomotion et morphologie du labyrinthe osseux sont recherchées chez les hominoïdes actuels. Les covariations entre le labyrinthe et le crâne sont étudiées chez Homo sapiens afin de déterminer l’influence sur la morphologie du labyrinthe de son intégration dans le crâne. Ces résultats sont enfin appliqués au labyrinthe de Toumaï, comparé à d’autres hominines fossiles.La morphométrie géométrique discrimine l’ensemble des espèces actuelles par l’orientation, la taille et la forme relatives de chacune des parties du labyrinthe. Cependant, la torsion et l’orientation relative des canaux semi-circulaires sont majoritairement liées à l’intégration du labyrinthe dans le crâne (orientation des pyramides pétreuses et de la face par rapport à la ligne médio-sagittale du basicrâne). Au contraire, l’excentricité des canaux et leur taille sont uniquement liées à la locomotion.Chez Sahelanthropus tchadensis, la taille des canaux semi-circulaires indique une espèce relativement plus agile que les grands singes. En revanche, il ne présente pas les rotations de canaux caractéristiques du genre Homo. La forme de ses canaux constitue une combinaison unique de caractères : canal postérieur rond et canal antérieur légèrement étiré, comme les humains et les australopithèques, mais canal latéral légèrement projeté postéro-latéralement, comme les gorilles et les babouins. Ceci indiquerait un comportement locomoteur associant le grimper vertical dans les arbres à des déplacements au sol bipèdes mais aussi quadrupèdes. / Humans are characterised by a specific form of bipedal locomotion. Toumaï, holotype specimen of Sahelanthropus tchadensis discovered in Chad, is the oldest known member of the human branch. Dated from 7 million years ago, it is very close to the dichotomy between this branch and the branch of chimpanzees. Therefore, it gives valuable information on the first stages of the evolution of locomotion is this group. The purpose of this work is to reconstruct the locomotor behaviour of Sahelanthropus tchadensis based on the study of the osseous part of its labyrinth, the balance organ.To this aim, the relationships between the locomotion and the bony labyrinth morphology are investigated in extent hominoids. The covariations between the labyrinth and the skull are studied in Homo sapiens in order to determine the influence of cranial integration on labyrinth morphology. Finally, these results are applied to the bony labyrinth of Toumaï, compared to other hominin fossils.Geometric morphometrics discriminates all extant species by the relative orientation, size and shape of each part of the labyrinth. However, the torsion and the relative orientation of the semicircular canals are mainly due to the integration of the labyrinth in the skull (petrous pyramids and face orientations relative to the midline of the basicranium). On the contrary, canal eccentricity and size are linked only to locomotion.In Sahelanthropus tchadensis, the canal size indicates that this species was more agile than great apes. However, it does not have the semicircular canal rotations characterising the genus Homo. The shape of its canals constitutes a unique combination of features: a round posterior canal and a slightly stretched anterior canal, as in humans and australopithecines, but a slightly posterolaterally projected lateral canal, as in gorillas and baboons. This is the sign of a locomotor behaviour associating vertical climbing in trees to both bipedalism and quadrupedalism on the ground.