Search results for "Evolution"
showing 10 items of 11096 documents
Categorical versus geometric morphometric approaches to characterizing the evolution of morphological disparity in Osteostraci (Vertebrata, stem Gnat…
2020
Morphological variation (disparity) tends to be evaluated through two non-mutually exclusive approaches: (i) quantitatively, through geometric morphometrics, and (ii) in terms of discrete, ‘cladistic’, or categorical characters. Uncertainty over the comparability of these approaches diminishes the potential to obtain nomothetic insights into the evolution of morphological disparity, and the few benchmarking studies conducted so far show contrasting results. Here, we apply both approaches to characterising morphology in the stem-gnathostome vertebrate clade Osteostraci, in order to assess congruence between these alternative methods as well as to explore the evolutionary patterns of the grou…
Étude paléobotanique d’une lentille argileuse cénomanienne de la carrière de Hucheloup, Maine-et-Loire, NO France : implications taxonomiques, strati…
2017
International audience; A Cenomanian clay lens in Hucheloup Quarry (Maine-et-Loire, north-western France) has yielded 82 foliar compressions and impressions, of which 62 were identified at several taxonomic levels. The plants are ascribed to diverse Pinales (27%), ferns (27%), Ginkgoales (26%), angiosperms (19%) and Cycadales (1%). The most abundant species in the assemblage are Frenelopsis alata (K. Feistmantel) E. Knobloch emend. J. Kvaček (Pinales) and Eretmophyllum obtusum (Velenovský) J. Kvaček (syn. E. andegavense Pons, Bourreau et Broutin) (Ginkgoales). Wood fragments, along with very well-preserved cuticles, have also been recovered and identified. The specimens are usually very fra…
Comment on the letter of the Society of Vertebrate Paleontology (SVP) dated April 21, 2020 regarding “Fossils from conflict zones and reproducibility…
2020
International audience
Tertiary ecosystems: evolution and palaeoenvironments
2017
The 1st International Meeting of Early-stage Researchers in Palaeontology (IMERP), heir of the Spanish and Portuguese EJIP (Encuentro de Jovenes Investigadores en Paleontologia/Meeting of Young Res...
Developmental aspects of morphological disparity dynamics: a simple analytical exploration
2011
15 pages; International audience; We devised a simple model for assessing the role of development in shaping the evolution of morphological disparity. Disparity of a clade at any given time is expressed in terms of the developmental dynamics that lead to the variety of adult morphotypes observed. We use assumed phenotypic manifestations of developmental processes, as they could be detected from allometric characterizations, to distinguish a few, nonexclusive types of evolutionary changes in ontogeny. On the basis of this formalization, we describe the diversification of hypothetical clades, using the standard curve of adult morphological disparity, the curve of juvenile disparity, and the c…
Assessing metabolic constraints on the maximum body size of actinopterygians: locomotion energetics of Leedsichthys problematicus (Actinopterygii, Pa…
2018
Maximum sizes attained by living actinopterygians are much smaller than those reached by chondrichthyans. Several factors, including the high metabolic requirements of bony fishes, have been proposed as possible body‐size constraints but no empirical approaches exist. Remarkably, fossil evidence has rarely been considered despite some extinct actinopterygians reaching sizes comparable to those of the largest living sharks. Here, we have assessed the locomotion energetics of Leedsichthys problematicus, an extinct gigantic suspension‐feeder and the largest actinopterygian ever known, shedding light on the metabolic limits of body size in actinopterygians and the possible underlying factors th…
Evolutionary trends within Jurassic ammonoids.
2015
An evolutionary trend is a pattern of traits shifting in a given direction over a sufficiently long period of time to be detected. In this study, we examine trends among Jurassic ammonoids. First, a compilation of selected literature on evolutionary patterns and trends leads to the conclusion that such trends have rarely been studied among Jurassic ammonoids and even more rarely are they formally studied using statistical tests. Second, a preliminary survey of trends for the entire Jurassic at the family level (based on four published articles) suggests two sustained trends occurred each lasting nearly 10 myr: the Early Jurassic and Middle Jurassic radiations, which were related to the firs…
Stéphane Peigné (1973-2017) – Nécrologie
2020
Stephane Peigne nous a quittes le 4 Decembre 2017 apres avoir lutte avec courage pendant des mois contre une terrible maladie. Il avait espere l'avoir vaincue en 2016 mais elle l'a rattrape inexorablement. Il etait ne en 1973 dans une petite commune de l'Est de la France et avait suivi sa scolarite dans la region jusqu'a son Baccalaureat. Il commenca des etudes superieures a l'universite de Nancy, dans un cursus en Sciences de la Nature et de la Vie, pour les poursuivre a l'Universite de Bourgogne par une licence de Biologie suivie d'une maitrise d'Ecologie. Cependant cette orientation vers la recherche en biologie evolutive et ecologique ne lui suffisait plus et, desireux d'inclure le temp…
First occurrence of fossil vertebrates from the Carboniferous of Colombia
2020
Data concerning Paleozoic vertebrates from the South American continent are still scarce. In Colombia, occurrences were until now restricted to the Late Devonian fish assemblage from Floresta and, ...
Macrofossil evidence of Late Holocene presence of Aldrovanda vesiculosa L. in Central-Eastern Europe (Poland) and East Africa (Tanzania)
2015
International audience; To date, the seeds of waterwheel plant (Aldrovanda vesiculosa) were only found in Europe, in sediments of the Eemian and Mazovian Interglacials. The absence of A. vesiculosa seeds in European Holocene deposits is probably due to unfavorable climatic conditions, i.e. lower temperature, during this period: in temperate zones, A. vesiculosa reproduces mainly in a vegetative way; it rarely blooms and only occasionally produces seeds. In this paper, subfossil seeds of A. vesiculosa were identified in two peat bogs: one (Sucha Kobyła) in SE Poland and another one (Kyambangunguru) in SW Tanzania. Single seeds of this plant were found in a peat layer from the Polish site for…