Extant therian mammals comprise marsupials and placentals. The lineages leading to these groups have been evolving separately since the Jurassic, resulting in substantially lower ecological and taxonomic diversity of marsupials than placentals. In order to elucidate the potential evolutionary mechanisms for this, the comparative cranial morphology between marsupials and placentals and patterns of taxonomic diversity through the fossil record were investigated. Cranial morphologies of a comprehensive range of extant placentals, marsupials and fossil metatherians were quantified using a geometric morphometrics. Variation in total skull morphology, and that of developmentally significant regions, of extant marsupials and placentals, was calculated and compared. Principal components analysis and delta variance tests were used to visualise and statistically investigate the data. Entire cranial shape was found to be significantly less varied in extant marsupials than in extant placentals, also true specifically in the viscerocranium. However, marsupial and placental neurocrania showed no significant difference in morphological varianc. Inclusion of fossil metatherians with the extant marsupial data did not significantly increase the variance of metatherian morphology. These findings are consistent with expectations based on the developmental constraint hypothesis. Metatherian fossil data were compiled from the literature and subjected to rigorous statistical adjustments, namely shareholder quorum subsampling (SQS) an d classic rarefaction, to ameliorate effects bias in the fossil record. Metatherian diversity was shown to fluctuate through time largely in accordance with major environmental changes. The diversity patterns revealed here contra st those based on raw data. Specifically, SQS analysis found North American Paleocene diversity to be higher than in the late Cretaceous, challenging the idea of an end Cretaceous decimation. Further, metatherian diversity in the late Miocene of Oceania was found to increase rather than decrease from the middle Miocene. This dual angle approach supports a combination of developmental and environmental effects on the evolution of metatherian biodiversity.

Abeer A.H. Alwan. / Includes bibliographical references (p. 129-133). / Research supported by a C.J. LeBel Fellowship and the National Science Foundation. Research supported by the National Institutes of Health. 8R01-DC00075

Les hominoïdes (Grands Singes), actuellement représentés par l'Homme, le Chimpanzé, le Gorille, l'Orang-outan et les Gibbons, sont apparus il y a environ 25 millions d'années (Ma) en Afrique. Leur histoire évolutive a été marquée par différentes dispersions entre l'Afrique, l'Europe et l'Asie, qui ont été possibles grâce à l'expansion de leur habitat : la forêt subtropicale à tropicale. Le but du travail présenté ici est de comprendre les changements climatiques qui ont marqué le Miocène (23 à 5 Ma environ), et d'étudier leur impact sur l'évolution des hominoïdes.Dans un premier temps, nous nous sommes intéressés à l'optimum climatique du Miocène moyen (environ 17-15 Ma), qui coïncide avec la première dispersion des hominoïdes hors d'Afrique, en particulier leur première occurrence dans le registre fossile européen. Nous avons ensuite étudié l'impact du retrait de la Paratéthys sur le climat et la végétation à l'échelle régionale grâce à un modèle atmosphérique zoomé. Dans un troisième temps, nous avons étudié la transition climatique du Miocène moyen (environ 14 Ma), période de fort refroidissement global et de croissance de la calotte de glace de l'Antarctique de l'Est. En particulier, nous avons testé l'impact de la fermeture du passage océanique de l'Est-Téthys sur la circulation océanique et le climat. Puis nous avons modélisé le climat et la végétation du Miocène supérieur (Tortonien, 11 à 7 Ma environ), et ainsi obtenu une série de simulations représentant l'évolution du climat au cours du Miocène. Enfin, ces simulations climatiques ont été utilisées pour forcer deux modèles de niche écologique, et ainsi étudier l'évolution de la répartition potentielle des homin / Hominoids (apes) are the modern humans, chimpanzees, gorillas, orangutans and gibbons. They arose in Africa approximately 25 million years ago (Ma). Hominoids' evolution was punctuated by diverse dispersals between the African, European and Asian continents, which were made possible by the expansion of their habitat: subtropical and tropical forests. The aim of the present study is to understand the climatic changes that occurred during the Miocene (ca. 23 to 5 Ma) and to study their impact on hominoids' evolution.First, we focused on the middle Miocene climatic optimum (17-15 Ma), which coincides with the first hominoids' dispersal out of Africa, in particular the first occurrence of hominoids in the European fossil record. We then studied the impact of the Paratethys Sea retreat on regional climate and vegetation with an atmospheric zoomed model. Thirdly, we studied the middle Miocene climatic transition (approximately 14 Ma), which corresponds to a global cooling and East Antarctica ice sheet growth. We particularly focused on the impact of the East-Tethys seaway closure on oceanic circulation and climate. Then we ran a Tortonian (late Miocene, ca. 11 to 7 Ma) experiment to obtain a series of simulations representing the evolution of climate and vegetation during the Miocene. Finally, we used these simulations to force two ecological niche models in order to study the evolution of hominoids' potential distribution during the Miocene.

The evolutionary history of archosauromorphs is of particular interest because it includes the origins of two of the best-known and most distinctive extant tetrapod groups: crocodylians and birds. In this thesis, the anatomy, taxonomy and systematics of the Permo-Triassic non-archosaur archosauromorphs are revised. A revision of the Permo-Triassic archosauromorph record indicates that only four Permian species are known and there are three valid proterosuchid species immediately after the Permo-Triassic boundary in South Africa. Analyses of cranial ontogenetic variation in \(Proterosuchus\) \(fergusi\) found that ontogenetic modification events (e.g. heterochrony) may have been key drivers of the evolution of the general shape of the skull at the base of Archosauriformes. A comprehensive quantitative phylogenetic analysis recovered a polyphyletic “Prolacertiformes”, restricted the taxonomic content of Proterosuchidae to only six species, Erythrosuchidae was composed of eight nominal species, and \(Euparkeria\) \(capensis\) was found as the sister-taxon of the clade that includes proterochampsians (doswelliids + proterochampsids) and archosaurs. The results obtained here suggest that the evolutionary history of the archosauriforms during the Early Triassic can be subdivided into a first phase characterized by the short-lived “disaster-clade” Proterosuchidae and a second phase that witnessed the initial morphological and probably palaeoecological diversification of the group.

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Ce travail s’est intéressé à la dynamique de peuplement du sud de la Sibérie et de l’Altaï à l’âge du Bronze (IIIème - Ier millénaire avant J.-C), période pendant laquelle les steppes eurasiennes auraient connues de nombreux mouvements de populations. Les analyses moléculaires ont portés sur 69 spécimens anciens. La stratégie adoptée a consisté, en plus de l’étude de l’ADN mitochondrial, à étudier les lignées paternelles de ces individus, ainsi que des marqueurs autosomaux, informatifs de leur origine biogéographique (AIM) et des caractères pigmentaires. L’ensemble des données moléculaires obtenues nous a permis de mettre en évidence une évolution du pool génique au sein de la région étudiée. Le faible effectif observé par groupe culturel ainsi que le processus de recrutement funéraire peut avoir biaisé une partie des analyses. Néanmoins, ces données moléculaires ont amené de nouveaux éléments pour la compréhension du peuplement de cette région qui apparaît comme un processus complexe. / The present work has focused on the settlement of the South Siberia and the Altai mountains during the Bronze Age (III-I millennium BC), period during which the Eurasian Steppes knew a lot of population movements. The molecular analyses were performed on 69 ancient samples. The used strategy consisted in the study of maternal and paternal lineages and autosomal markers informative of biogeographical ancestry (AIM) and physical appearance. Taken together, these results show an evolution of the genetic pool in this area during the Bronze Age. The low effective observed in each cultural group and the funeral recruitment could of course have induced a bias in some analyses. Nevertheless, these molecular data gave new elements to understand the settlement of this region which seems to be a complex process that it will be necessary to deepen with new paleogenetic even paleogenomic studies.

Die unkontrollierte menschliche Entwicklung beeinflusst alle Aspekte der Interaktionen und Prozesse von Ökosystemen (Ökosystemfunktionen), einschließlich derjenigen, die für Menschen von Nutzen sind und sein werden (Ökosystemdienstleistungen). In dieser Arbeit habe ich einen neuen analytischen Ansatz entwickelt, der auf der Netzwerkanalyse basiert, um die Strukturdynamik von Ökosystemen in der Tiefe zu untersuchen. Ich habe diesen Ansatz validiert, indem ich den gut untersuchten Fossilienbestand großer Säugetiere der Iberischen Halbinsel während der letzten 21 Ma verwendet habe. Das funktionelle System durchlief lange Perioden der Stabilität, unterbrochen von einer schnellen Reorganisation, die einen neuen stabilen Zustand fand. Hohe funktionelle Diversität und Reichhaltigkeit befeuert mit der Zeit zunehmende Belastbarkeit der Funktionsstruktur (Versicherungseffekt). Dann verwende ich eine Kombination aus funktionaler Diversität (fdiv) und Netzwerkanalyse über einen beispiellosen Datensatz von großen Pflanzenfressern weltweit, der sich über die letzten 65 Millionen Jahre erstreckt. Es gab einen anfänglichen Trend zur Zunahme der funktionellen Diversität, vermittelt durch einen Nettogewinn an funktionellem Reichtum, der 20 Ma erreichte, wahrscheinlich angeheizt durch die Bildung der sogenannten Gomphotherium-Landbrücke. Danach blieb der fdiv des Systems hoch und erreichte das maximale Niveau von 10 Ma, als das System viele Arten mit ähnlichen ökologischen Rollen (funktionelle Sättigung) angesammelt hatte, was letztendlich ihren funktionellen Zusammenbruch provozierte. Danach zeigte das System eine schnellere ökologische Verarmung, die während des Beginns der pleistozänen Vergletscherung um etwa 2,5 Ma zunahm. In Bezug auf die funktionelle Struktur stellen wir fest, dass känozoische große Pflanzenfressergemeinschaften lange Perioden der Stabilität durchlebten, gefolgt von der Reorganisation ihrer funktionellen Struktur in neue stabile Zustände (um 20 und 10 Ma). / Uncontrolled human development is affecting all aspects of ecosystems' interactions and processes (ecosystem functioning), including those that are, and will be, beneficial to people (ecosystem services). In this thesis I developed a new analytical approach based on network analysis to study deep time ecosystem structure dynamics. I validated this approach using the well studied large mammal fossil record of the Iberian Peninsula during the last 21 Ma. The functional system underwent long periods of stability punctuated by a rapid reorganization finding a new stable state. High functional diversity and richness fueled the time increasing resilience of the functional structure (insurance effect). Then, I use a combination of functional diversity (fdiv) and network analysis over an unprecedented dataset of worldwide large herbivores spanning the last 65 Myrs. There was an initial trend towards the increment of functional diversity, mediated by a net gain in functional richness that peaked 20 Ma, likely fueled by the formation of the so-called Gomphotherium land bridge. Thereafter, the system’s fdiv remained high reaching the maximum level 10 Ma, when the system had accumulated many species with similar ecological roles (functional saturation), which ultimately provoked their functional collapse. After that, the system showed a faster ecological impoverishment increasing around 2.5 Ma during the beginning of Pleistocene glaciations. Regarding the functional structure, we find that Cenozoic large herbivore communities experienced long periods of stability followed by the reorganization of their functional structure in new stable states (around 20 and 10 Ma).

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