Academic literature on the topic 'Radiolaires – Morphologie (biologie) – Évolution'
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Journal articles on the topic "Radiolaires – Morphologie (biologie) – Évolution":
Punt, W. "Morphologie pollinique: biologie, systématique et évolution." Review of Palaeobotany and Palynology 91, no. 1-4 (March 1996): 428–29. http://dx.doi.org/10.1016/s0034-6667(96)90005-6.
Dissertations / Theses on the topic "Radiolaires – Morphologie (biologie) – Évolution":
Carlsson, Veronica. "Artificial intelligence in radiolarian fossil identification : taxonomic, biostratigraphic and evolutionary implications." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR092.
Micropaleontology is not only about studying the organisms themselves, rather understanding Earth's past environments, with applications ranging from biostratigraphy to paleoceanography as well as being able to study evolutionary changes within morphospecies in time and space. This field is facing numerous challenges, since the analysis of microfossils demands significant human effort and taxonomic expertise, often leading to inconsistencies in interpretations. This work focuses on the application of using Artificial Intelligence (AI), such as Artificial Neural Networks (ANNs), for automatic image recognition of tropical Atlantic middle Eocene radiolarians. Large datasets have been constructed, in order to train different neural networks and our results show that the neural networks can automatically classify several different classes of radiolarians down to a species level, as well as in many cases being able to identify closely related species and even evolutionary transition morphotypes. It has also been able to correctly identify less broken or blurry radiolarians. It was also successfully applied to automatic image recognition for a biostratigraphic work, which in general could detect more general ages or highly precise bio events. This work includes the use of the classical neural network approaches for analysing visual context such as Convolutional Neural Networks (CNNs) but also includes the use of Spiking Neural Networks (SNNs), which is not as commonly used for automatic image recognition, as CNNs. SNNs resulted in almost or equal amount of accuracy obtained as for CNNs, just that the use is more computational efficient and takes up less memory. There have also been some comparisons using traditional morphometric analyses, such as Linear Discrimination Analysis (LDA), giving approximately the same kind of results. Our research not only aims to simplify and speed up the analysis process but also helps in increasing the accuracy and consistency of micropaleontological interpretations, which eventually, will contribute to the high-resolution studies in order to understand Earth's past history
Dutel, Hugo. "Histoire évolutive, morphologie fonctionnelle et développement des cœlacanthes mésozoïques et actuels." Paris, Muséum national d'histoire naturelle, 2013. http://www.theses.fr/2013MNHN0021.
Coelacanths (Actinistia) form a clade of lobe-finned vertebrates that are nowadays represented by a single genus, Latimeria. In this thesis, I first present a redescription of poorly known fossil coelacanths Trachymetopon and Megalocoelacanthus from the Jurassic and Cretaceous periods. These fossils give new insights into the phylogenetic relationships and paleobiogeography of the Mesozoic coelacanths. Moreover, they shed light on the variability in the skull anatomy in large-sized, fossil coelacanths. Then, I present unique data on the early development of the extant coelacanth Latimeria based on X-ray synchrotron microtomography, and discuss of the importance of developmental data to our understanding of the evolution of the cranial system in coelacanths. Investigation of the functional significance of the morphological variation in skull anatomy is also needed to understand the evolutionary trade-offs in the cranial system of coelacanths, and to make inferences on the feeding behavior and ecology of fossil coelacanths. However this objective first necessitates an in-depth understanding of the skull mechanics in the extant coelacanth Latimeria, which is investigated in the rest of this thesis. Among extant vertebrates, Latimeria is unique in having a skull divided into an anterior and a posterior part, articulated by means of an intracranial joint. This joint is associated with a paired muscle, the basicranial muscle. This complex articulation was previously thought to allow an elevation of the snout by 15° to 20°, which would enhance mouth opening distance and allowing the animal to perform a powerful suction. The basicranial muscle was thought to depress the anterior portion of the skull from its elevated state during mouth closure. I re-describe the musculo-skeletal anatomy of the skull based on the dissection of an adult coelacanth specimen. These new data suggest that the intracranial joint and the hyoid apparatus are less mobile than previously thought. The elevation of the anterior portion of the skull is unlikely. However, a small but distinct ventroflexion of the anterior portion of the skull from its resting position under the action of the basicranial muscle is likely based on the anatomy of the joint. Using a static equilibrium model, I show that the basicranial muscle increases the overall bite force generated by Latimeria, suggesting that the role of a functional intracranial joint in coelacanths may be associated with bite force generation rather than suction feeding. Preliminary results of finite element analysis on biting in Latimeria, as well as future research directions are finally presented. The understanding of the skull mechanics in Latimeria will serve to investigate in future work the functional implications on feeding of the variations in skull anatomy described in fossil coelacanths
Charles, Cyril. "Evo-Dévo des dents chez les rongeurs murinés : des gènes à la morphologie." Poitiers, 2008. http://www.theses.fr/2008POIT2330.
Among mammals, tooth rows are an ideal model to study mechanisms linking evolution and developmental biology. Many genes involved in dental development have already been identified in the laboratory mouse. However, the function of these genes in the course of evolution remains highly unknown. This thesis aims at identifying developmental genes involved in dental evolution among mammals and particularly among rodents. In a first part, various dental anomalies occurring among wild populations of eutherian mammals are presented and are discussed regarding dental development models. These anomalies also underline various evolutionary trends among eutherian mammals. In a second part, dental anomalies associated to losses of functions of two Eda pathway genes (Eda and Edar), are deeply investigated. This study brings to the fore new information on the function of these two genes on odontogenesis. The results also show that the Eda signaling pathway is potentially involved in dental evolution among rodents, particularly in the acquisition of the muroid dental formula. Morphological comparisons between Eda pathway mutants and various extent rodent species indicate a potential implication of this pathway in the setting up of the atypical dental morphology of Rhynchomys (Muridae, Rodentia). Eventually, a preliminary study of the tooth morphology of mice carrying losses of functions of the Fgf3 gene and its antagonists, Sprouty2 and Sprouty4, indicates a potential implication of these genes in the acquisition of the murin dental plan and some similarities with primitive murid species. All of the results indicate that the studied genes involved in dental development may also be implicated in the dental modifications in the course of evolution among Muroidea
Isnard, Sandrine. "Biomécanique et évolution de la forme grimpante chez les palmiers (Arecaceae)." Montpellier 2, 2005. http://www.theses.fr/2005MON20214.
The climbing growth form has appeared several times during palm evolution and in phylogenetically distant groups. Among the 2700 species recognised in the Arecaceae, more than 500 are climbers. This study deals with species belonging to the two subfamilies, which include climbing forms, the Arecoideae and the Calamoideae, from South America and South-east Asia respectively. The main objective is to understand the mechanical, morphological and developmental traits linked to the climbing habit in a family that lacks secondary growth. The results are discussed using recent phylogenetic reconstructions and are compared with previous studies on the mechanical architecture of dicotyledonous lianas. The first part deals with the mechanical architecture and development of axes. The results emphasize the mechanical role of the leaf sheath and specific adaptations of the stem for the climbing habit in each subfamily. In the second part, morphological and structural organisation of attachment organs (flagellum and cirrus) are investigated. Breaking forces of hooks and acanthophylls, and the variations of mechanical properties along cirri and flagellae are discussed in terms of the plant ecology, its potential for occupying space and its attachment to supports. The results suggest that the apparently strongly convergent evolution towards the climbing habit has in fact produced specific mechanical architectures according to the phylogenetic constraints of different genera. In both subfamilies the occurrence of the climbing growth form may have resulted from heterochronic processes, involving the reduction of the establishment phase that characterise arborescent palms
Rousset, Vincent. "Phylogénie moléculaire et morphologique des annélides." Paris, Muséum national d'histoire naturelle, 2004. http://www.theses.fr/2004MNHN0005.
Interrelationships among the major Annelida groups remain unresolved, although addressed earlier both in molecular and morphological studies. We attempted to answer to some of these issues in four studies. (1) Combined parsimony analyses of 28S rRNA and morphological data to assess the relationships of Alvinellidae, a group known only from deep-sea hydrothermal vents. Our results indicate that : Trichobranchidae is separate from Terebellidae and may be the sister of Alvinellidae, and Ampharetidae and Terebellidae are monophyletic but require further attention. (2) We assessed the phylogenetic position of Siboglinidae (the previous phyla Pogonophora and Vestimentifera, but now nested within polychaetes). Combined parsimony analyses of molecular (18S and 28S rRNA) and morphological data provide strong support for a sister-group relationship between Siboglinidae and Oweniidae, and for the monophyly of Terebelliformia, but demonstrate that the delineations of Terebellida and Sabellida require further study. (3) Based on 18S, 28S and 16S rRNA sequences, we analysed relationships and position of clitellates (earthworms and leeches). Parsimony and bayesian analyses indicate that clitellates have a sistergroup within polychaetes, consisting of a subgroup of a polyphyletic Scolecida, but also delineation problems with polychaetes and annelids. (4) Results obtained from parsimony and bayesian analyses of 117 terminals and 18S, 28S, 16S rRNA and histone H3 sequences indicate polyphyly of Annelida, owing to the nested positions of one sipunculan, one nemertean, one brachiopod and two molluscs, polyphyly of major groups of polychaetes and corroborate the results of the third study on the position of Clitellata
David, Romain. "Le système des canaux semi-circulaires des archosaures : anatomie, morphométrie, morphologie fonctionnelle, évolution." Paris, Muséum national d'histoire naturelle, 2011. http://www.theses.fr/2011MNHN0038.
Semicircular canals are peripheral organs of the vestibular system which are specialised in the detection of head rotations. The signals they transmit to the central nervous system are integrated with visual, proprioceptive and other vestibular signals in order to provide a stable reference frame through head and visual field stabilisation. This allows navigation, motor control and optic flow integration to optimally occur, particularly during locomotion. Here I provide a new methodological framework to analyse the vestibular capabilities of extant and extinct taxa, based on the functional structure of the semicircular canals' system (SCFS). The calculation of the SCFS takes the most of semicircular canals' morphology and empirical relations retrieved upon membranous labyrinths. It provides us with the estimated in-plane sensitivity and maximal response axis of each semicircular canal. This new methodological framework allows us to study absolute and relative overall sensitivity of a semicircular canals' system, along with its directional sensitivity and coding patterns. Data from computed tomography scanning of extant and extinct specimens allow us to reconstruct, to describe and to analyse the bony labyrinth of 39 archosaurs and the membranous labyrinth of 5 tetrapods. We provide evidence that the semicircular canals carry a phylogenetic informative signal, and we retrieved the dinosaurian origin of the clade Aves based on semicircular canals' characters only, for the first time. We show that the shape of the semicircular canals of archosaurs is correlated with the phylogenetic position of the specimens, but also with their biomechanical capabilities, suggesting that the diversification of the archosaurs came along with biomechanical adaptations of the inner ear. We demonstrate that the semicircular canals' system detects some rotations more precisely than others, and that there exist numerous patterns of detection that could eventually be correlated with locomotor repertoires. Finally, we find that birds using flapping flight present an optimisation toward a decrease in the biomechanical sensitivity of their semicircular canals' system, and we deduce from this analysis that the semicircular canals‟ system of Archaeopteryx does not theoretically prevent it to perform flapping flight
Eléaume, Marc. "Approche morphométrique de la variabilité phénotipique : conséquences systématiques et évolutives : application aux crinoïdes actuels (Crinoidea : Echinodermata)." Paris, Muséum national d'histoire naturelle, 2006. http://www.theses.fr/2006MNHN0031.
The taxonomy and evolutionary history of crinoids (Crinoidea: Echinodermata) are based on skeletal features which are known to vary as a function of size, age or environmental conditions. Classical multivariate morphometry applied to comatulids allows proposing taxonomic hypothesis which can be tested by the analysis of discrete characters. Florometra mawsoni and Solanometra antarctica are congeneric. Florometra asperrima and F. Serratissima are conspecific. The structure of the calix and articular facets display synapomorphies. Promachocrinus kerguelensis shows two different morphotypes that are differently distributed in the biogeographical provinces of the Southern Ocean. Notocrinus virilis and N. Mortenseni are not congeneric. Comatulids are replaced among the crinoids using a combined analysis of morphological and molecular characters. Primary homologies are tested and homoplasies discussed
Falconnet, Jocelyn. "Diversification initiale des amniotes : l'apport des amniotes français." Paris, Muséum national d'histoire naturelle, 2010. http://www.theses.fr/2010MNHN0035.
Mignot, Yannick. "Un problème de paléobiologie chez les ammonoïdes (Cephalopoda) : croissance et miniaturisation en liaison avec les environnements." Lyon 1, 1992. https://tel.archives-ouvertes.fr/tel-02426776/document.
Bienvenu, Thibaut. "L'Endocrâne de Sahelanthropus Tchadensis (Hominidae, Miocène supérieur du Tchad) : reconstitution 3D et morphologie : comparaison avec les hominoïdes actuels et fossiles." Poitiers, 2010. http://theses.univ-poitiers.fr/26582/2010-Bienvenu-Thibaut-These.pdf.
The fossil cranium of Sahelanthropus tchadensis, nicknamed Toumaï, was discovered in 2001 at Toros-Menalla (Chad). Currently, it is the oldest known hominid, dated at 7 Ma. It is very close, temporally and phylogenetically, to the dichotomy between humans and chimpanzees. Using synchrotron X-ray imaging techniques, fragmented inner table was virtually extracted out of the matrix filling the skull. Postmortem distortions of the endocranial surface have been corrected. Finally, filling the gaps resulted in the virtual endocast of the oldest known hominid. The endocast of Toumaï gives a first insight into the morphology of the brain of Late Miocene hominids. Comparison with a sample of extant and fossil primates, using both traditional and geometric morphometrics methods, enabled assessing primitive and derived endocranial traits of these hominids. The hypothetical endocranial morphology of the last common ancestor to humans and chimpanzees differs from those of extant great apes in many aspects, notably greater relative length, frontal lobes more stretched medio-laterally, and cerebellar lobes less protruding posteriorly, confirming that extant great apes are not good proxies to infer hominid primitive morphology. The endocast of Toumaï is characterized by a flexed cranial base and occipital lobes strongly protruding posteriorly. These structural changes provide new clues of the bipedal locomotor mode of Sahelanthropus tchadensis. The endocast of Toumaï does not show any clear feature of neural reorganization
Books on the topic "Radiolaires – Morphologie (biologie) – Évolution":
H, Nitecki Matthew, and Nitecki Doris V, eds. Evolutionary innovations. Chicago: University of Chicago Press, 1990.
Goodwin, B. C. How the leopard changed its spots: The evolution of complexity. London: Phoenix, 1995.