Search results for "Cultura"
showing 10 items of 14525 documents
Biodiversity is not (and never has been) a bed of roses!
2011
9 pages; International audience; Over the last decades, the critical study of fossil diversity has led to significant advances in the knowledge of global macroevolutionary patterns of biodiversity. The deep-time history of life on Earth results from background originations and extinctions defining a steady-state, nonstationary equilibrium occasionally perturbed by biotic crises and "explosive" diversifications. More recently, a macroecological approach to the large-scale distribution of extant biodiversity offered new, stimulating perspectives on old theoretical questions and current practical problems in conservation biology. However, time and space are practically distinct, but functional…
Allometric space and allometric disparity: a developmental perspective in the macroevolutionary analysis of morphological disparity.
2008
8 pages; International audience; Here, we advance novel uses of allometric spaces--multidimensional spaces specifically defined by allometric coefficients--with the goal of investigating the focal role of development in shaping the evolution of morphological disparity. From their examination, operational measures of allometric disparity can be derived, complementing standard signals of morphological disparity through an intuitive and process-oriented refinement of established analytical protocols used in disparity studies. Allometric spaces thereby become a promising context to reveal different patterns of evolutionary developmental changes and to assess their relative prevalence and import…
The evolution of gigantism in active marine predators
2017
A novel hypothesis to better understand the evolution of gigantism in active marine predators and the diversity of body sizes, feeding strategies and thermophysiologies of extinct and living aquatic vertebrates is proposed. Recent works suggest that some aspects of animal energetics can act as constraining factors for body size. Given that mass-specific metabolic rate decreases with body mass, the body size of active predators should be limited by the high metabolic demand of this feeding strategy. In this context, we propose that shifts towards higher metabolic levels can enable the same activity and feeding strategy to be maintained at bigger body sizes, offering a satisfactory explanatio…
Constraint and adaptation in the evolution of carnivoran skull shape
2011
The evolutionary history of the Order Carnivora is marked by episodes of iterative evolution. Although this pattern is widely reported in different carnivoran families, the mechanisms driving the evolution of carnivoran skull morphology remain largely unexplored. In this study we use coordinate-point extended eigenshape analysis (CP-EES) to summarize aspects of skull shape in large fissiped carnivores. Results of these comparisons enable the evaluation of the role of different factors constraining the evolution of carnivoran skull design. Empirical morphospaces derived from mandible anatomy show that all hypercarnivores (i.e., those species with a diet that consists almost entirely of verte…
A model for planktic foraminiferal shell growth
1993
In this paper we analyze the laws of growth that control planktic foraminiferal shell morphology. We assume that isometry is the key toward the understanding of their ontogeny. Hence, our null hypothesis is that these organisms construct isometric shells. To test this hypothesis, geometric models of their shells have been generated with a personal computer. It is demonstrated that early chambers in log-spirally coiled structures cannot follow a strict isometric arrangement. In the real world, the centers of juvenile chambers deviate from the logarithmic growth curve. Juvenile stages are generally more planispiral and contain more chambers per whorl than adult stages. These traits are shown …
Trackways of Arthropleura from the Late Pennsylvanian of Graissessac (Hérault, southern France)
2019
International audience; The Late Pennsylvanian deposits of the Graissessac Basin (southern France) are well known for their abundant and diversified plant remains. Here we report on seven trackways of giant millipede-like arthropods recently discovered from two surfaces. These traces are ascribed to Diplichnites cuithensis. The trackways are up to 200 cm long, up to 36 cm wide, straight to curved and consist of two parallel rows of numerous and elongated appendage imprints that are oriented perpendicular to the midline. Although body fossils of giant millipede-like arthropods remain unknown in sediments from this basin, the morphology and size of the trace fossils indicate that the trails w…
Eucynodont teeth from the Late Triassic of Krasiejów, Southern Poland
2021
Recent discoveries of Mammaliamorph teeth in the Keuper of southern Poland have extended the global record of eucynodonts in the Late Triassic and revealed a significant diversity of the group at that time. Here,we expand on this record with the description of new cynodont postcanine teeth from the Krasiejów bone bed. They show the dental morphology typical for Dromatheriidae, with a single root and crown without cingulum. We assigned them to Polonodon woznikensis, described from Woźniki. None of the 38 teeth from Krasiejów and Woźniki exhibit signs of serious wear, potentially indicating a very fast rate of tooth replacement in Polonodon.
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…
Evaluating the influences of temperature, primary production, and evolutionary history on bivalve growth rates
2019
AbstractOrganismal metabolic rates reflect the interaction of environmental and physiological factors. Thus, calcifying organisms that record growth history can provide insight into both the ancient environments in which they lived and their own physiology and life history. However, interpreting them requires understanding which environmental factors have the greatest influence on growth rate and the extent to which evolutionary history constrains growth rates across lineages. We integrated satellite measurements of sea-surface temperature and chlorophyll-a concentration with a database of growth coefficients, body sizes, and life spans for 692 populations of living marine bivalves in 195 s…