Evolution and development of the strepsirrhine primate skull

Since Haeckel (1866), the evolutionary modification of ontogeny has been recognized as an important source of morphological innovation. Due to recent advances in developmental genetics and phenotypic analysis, evolutionary developmental (evo-devo) studies have regained considerable interest and led to fundamental changes in our understanding of how ontogeny and phylogeny are related. This thesis investigates the relationship between ontogeny and phylogeny in strepsirrhine primates. The suborder Strepsirrhini, which comprises galagos, lorises and Malagasy lemurs, is thought to have retained most of the ancestral primate condition (as opposed to the suborder Haplorrhini, which comprises tarsiers and anthropoids). Nevertheless, strepsirrhines are highly diverse in their morphology. Here, the focus is on cranial diversity, which is analyzed from a developmental perspective with a new set of geometric morphometric tools. First, patterns of cranio-mandibular variability in extant adult primates are analyzed. Taking into account the phylogenetic constraints applying to the skull morphology permits a quantification of how dietary specialization and activity patterns influence cranio-mandibular morphology in both primates suborders. Also, the skull morphology in strepsirrhines and haplorrhines is clearly distinct, and it is shown here that differences between and within infraorders can be traced back to differences in developmental modes. According to a hypothesis proposed by Beard (1988), “strepsirrhinism” represents the primitive condition of the primate skull. This thesis shows that the cranial morphology of the Omomyidae – a basal haplorrhine taxon comprising the genera Rooneyia, Necrolemur and Microchoerus – is closer to that of extant strepsirrhines than to that of haplorrhines, while the cranial morphology of Tarsius is closer to that of other extant haplorrhines, i.e., the anthropoids. Thus, it is probable that the shift towards a modern haplorrhine morphology occurred in one omomyid lineage, to the exclusion of the three genera mentioned above. New arguments are proposed to support the hypothesis that the cranio-mandibular morphologies of the cheirogaleids and galagids are the least derived from the ancestral condition of toothcombed strepsirrhines. This thesis presents a comparative geometric morphometric analysis of cranio-mandibular development in ten strepsirrhine and two haplorrhine species. Haplorrhines and strepsirrhines differ widely in ontogenetic trajectory direction, length and position. Within the strepsirrhines, divergence between taxon-specific ontogenetic trajectories and allometric grade shifts are more pronounced in lemurs than in lorises. This pattern of evolutionary modification of ontogenetic trajectories is interpreted in the context of the rapid adaptive radiation of lemurs. The last section uses insights obtained from the evolutionary developmental analysis of extant taxa for a comparative analysis of fossil strepsirrhine taxa. The morphologies of extant and extinct strepsirrhines are compared. In particular, the morphology of the skull is well known from two adapiform subfamilies, Adapinae and Notharctinae. Among the adapines, a size increase has occurred in the Leptadapis lineage via a shift in allometric grade, which suggests phyletic gigantism in this genus. Adapiforms exhibit longer ontogenetic trajectories than extant strepsirrhines. A trend toward a shortening of ontogenetic trajectories has occurred in the evolutionary history of strepsirrhines. This can be related to a context of general increase in encephalization within this lineage. Abstract 2: Due to recent advances in developmental genetics and phenotypic analysis, evolutionary developmental (evo-devo) studies regained considerable interest, and led to fundamental changes in our understanding of how ontogeny and phylogeny are related. This thesis investigates the relationship between ontogeny and phylogeny in strepsirrhine primates. Here, the focus is on cranial diversity, which is analyzed from a developmental perspective, and with a new set of geometric morphometric tools. A comparative geometric morphometric analysis of cranio-mandibular development is conducted in ten strepsirrhines and two haplorrhine species. Haplorrhines and strepsirrhines differ widely in ontogenetic trajectory direction, length and position. Within the strepsirrhines, divergence between taxon-specific ontogenetic trajectories and allometric grade shifts are more pronounced in lemurs than in lorises. The insights obtained from the evolutionary developmental analysis of extant taxa are used for a comparative analysis of Eocene fossil strepsirrhine taxa belonging to the infraorder Adapiformes. Among the adapine adapiforms, an increase in size via allometric grade shift has occurred in the Leptadapis lineage, which suggests phyletic gigantism in this genus. Adapiforms exhibit longer ontogenetic trajectories than extant strepsirrhines. A trend toward a shortening of ontogenetic trajectories has occurred in the evolutionary history of strepsirrhines. This trend can be related to the expression of developmental constraints in a context of selection for increase in encephalization. Zusammenfassung 2 Aufgrund jüngerer Fortschritte in der Entwicklungsgenetik sowie der phänotypischen Analyse ist das Interesse an der evolutionären Entwicklungsbiologie enorm gestiegen, und hat zu grundlegenden Veränderungen im Verständnis der Beziehung von Ontogenese und Phylogenese geführt. Diese Arbeit untersucht die Beziehung zwischen Ontogenese und Phylogenese am Beispiel der Feuchtnasenaffen (Strepsirrhini). Die kraniale Diversität dieser Primaten wird mit einer Palette neuer morphometrischer Werkzeuge analysiert. Resultate aus der evolutionären Entwicklungsbiologie existierender Taxa werden für eine vergleichende Analyse von fossilen Taxa der aus dem Eozän stammenden Unterordnung Adapiformes benutzt. Die evolutionäre Geschichte der Strepsirhini weist auf eine Tendenz in Richtung verkürzter ontogenetischer Trajektorien hin. Dies kann in einem Zusammenhang allgemeiner Enzephalisation in dieser Abstammungslinie gesehen werden

Imaging extended sources with coded mask telescopes: Application to the INTEGRAL IBIS/ISGRI instrument

Context. In coded mask techniques, reconstructed sky images are pseudo-images: they are maps of the correlation between the image recorded on a detector and an array derived from the coded mask pattern. Aims. The INTEGRAL/IBIS telescope provides images where the flux of each detected source is given by the height of the local peak in the correlation map. As such, it cannot provide an estimate of the flux of an extended source. What is needed is intensity sky images giving the flux per solide angle as typically done at other wavelengths. Methods. In this paper, we present the response of the INTEGRAL IBIS/ISGRI coded mask instrument to extended sources. We develop a general method based on analytical calculations in order to measure the intensity and the associated error of any celestial source and validated with Monte-Carlo simulations. Results. We find that the sensitivity degrades almost linearly with the source extent. Analytical formulae are given as well as an easy-to-use recipe for the INTEGRAL user. We check this method on IBIS/ISGRI data but these results are general and applicable to any coded mask telescope.Comment: 9 pages, 6 figures, Accepted for publication in A&

Visualizing shape transformation between chimpanzee and human braincases

The quantitative comparison of the form of the braincase is a central issue in paleoanthropology (i.e., the study of human evolution based on fossil evidence). The major difficulty is that there are only few locations defining biological correspondence between individual braincases. In this paper, we use mesh parameterization techniques to tackle this problem. We propose a method to conformally parameterize the genus-0 surface of the braincase on the sphere and to calibrate the parameterization to match biological constraints. The resulting consistent parameterization gives detailed information about shape differences between the braincase of human and chimp. This opens up new perspectives for the quantitative comparison of "featureless” biological structure

South-West extension of the hard X-ray emission from the Coma cluster

We explore the morphology of hard (18-30 keV) X-ray emission from the Coma cluster of galaxies. We analyze a deep (1.1 Ms) observation of the Coma cluster with the ISGRI imager on board the \emph{INTEGRAL} satellite. We show that the source extension in the North-East to South-West (SW) direction ($\sim 17'$) significantly exceeds the size of the point spread function of ISGRI, and that the centroid of the image of the source in the 18-30 keV band is displaced in the SW direction compared to the centroid in the 1-10 keV band. To test the nature of the SW extension we fit the data assuming different models of source morphology. The best fit is achieved with a diffuse source of elliptical shape, although an acceptable fit can be achieved assuming an additional point source SW of the cluster core. In the case of an elliptical source, the direction of extension of the source coincides with the direction toward the subcluster falling onto the Coma cluster. If the SW excess is due to the presence of a point source with a hard spectrum, we show that there is no obvious X-ray counterpart for this additional source, and that the closest X-ray source is the quasar EXO 1256+281, which is located $6.1'$ from the centroid of the excess. The observed morphology of the hard X-ray emission clarifies the nature of the hard X-ray "excess" emission from the Coma cluster, which is due to the presence of an extended hard X-ray source SW of the cluster core.Comment: 7pages, 10 figure

Grain and phase stress criteria for behaviour and cleavage in duplex and bainitic steels

Stress analyses by X-ray diffraction are performed on a cast duplex (32% ferrite) stainless steel elbow and a bainitic (95% ferrite) pressure vessel steel. During an in situ tensile test, micrographic observations are made (visible glides and microcracks) and related to the stress state determined in the individual ferritic grains (aged duplex) and the ferritic phase (bainite loaded at low temperatures). Several material parameters have been identified at different scales, as for example, the critical resolved shear stress of 245 MPa for the aged ferritic grain (duplex) or 275 MPa for bainite (–60 ◦C), a crystallographic cleavage propagation criterion of 465 MPa (stress normal to {100} planes), and a fracture stress of approximately 700 MPa in the ferritic phase. Even though the two steels are different in many respects, the macroscopic fracture strains and stresses are well predicted by the polycrystalline model developed for bainite, whatever the temperatures tested (considering 7% of the grains reaching the local criterion)

Coma revealed as an extended hard X-rays source by INTEGRAL IBIS/ISGRI

Aims. We report the INTEGRAL/IBIS observations of the Coma Cluster in the hard X-ray/soft-ray domain. Methods. Since the Coma Cluster appears as an extended source, its global intensity and significance cannot be directly extracted with standard coded mask analysis. We used the method of imaging the extended sources with a coded mask telescope developed by Renaud et al. (2006). Results. The imaging capabilities and the sensitivity of the IBIS/ISGRI coded mask instrument allows us to identify for the first time the site of the emission above ~ 15 keV. We have studied the Coma Cluster morphology in the 18-30keV band and found that it follows the prediction based on X-ray observations.We also bring constraints on the non-thermal mechanism contribution at higher energies.Comment: 4 pages, 4 figures, Accepted for publication in A&A Letter

The signature of 44Ti in Cassiopeia A revealed by IBIS/ISGRI on INTEGRAL

We report the detection of both the 67.9 and 78.4 keV 44Sc gamma-ray lines in Cassiopeia A with the INTEGRAL IBIS/ISGRI instrument. Besides the robustness provided by spectro-imaging observations, the main improvements compared to previous measurements are a clear separation of the two 44Sc lines together with an improved significance of the detection of the hard X-ray continuum up to 100 keV. These allow us to refine the determination of the 44Ti yield and to constrain the nature of the nonthermal continuum emission. By combining COMPTEL, BeppoSAX/PDS and ISGRI measurements, we find a line flux of (2.5 +/- 0.3)*10(-5) cm(-2) s(-1) leading to a synthesized 44Ti mass of 1.6 (+0.6-0.3)*10(-4) solar mass. This high value suggests that Cas A is peculiar in comparison to other young supernova remnants, from which so far no line emission from 44Ti decay has been unambiguously detected.Comment: 5 pages, 4 figures, Accepted for publication in ApJ