Search results for "Trias"
showing 10 items of 168 documents
Challenging Darwin: Evolution of Triassic Conodonts and Their Struggle for Life in a Changing World
2017
Abstract The phylogeny and distribution of Triassic conodonts reveal many aspects of their natural history. Conodonts incorporate the morphologic response to temperature as well as to eustatic cycles. Speciation, radiation, and extinction are not fortuitous and evolution uses heterochrony (progenesis and neoteny) in response to stress-generating events. Proteromorphosis (reappearance of ancestral morphs) and paedomorphosis (retention of juvenile traits) is a reaction to sublethal environmental stress. This often follows radiation of fully developed forms in the recovery stage after extinction that timely matches transgressions. Evolutionary retrogradation (neoteny) during eustatic high stan…
The genus Palaeolituonella (Foraminifer) and description of Palaeolituonella angulata nov. sp. from Upper Triassic reef limestones of the Tethys
2009
The Potential Geosite of the “Libeccio Antico” Quarries: a Sedimentological and Stratigraphic Characterisation of Ornamental Stone from Mt Cocuccio, …
2018
The Custonaci marble district of western Sicily is known for the production of a valuable ornamental stone that has been, and nowadays is exploited due to its suitable properties and aesthetic qualities. The “Libeccio Antico” was, among the “marbles”, the most appreciated ornamental stone during the Baroque Age (the XVII–XVIII centuries), due to its strong polychrome contrasts from ivory to yellow, green or dark red. This polychrome pattern is the result of dissolution processes that involved an Upper Triassic peritidal limestone. The varicoloured sediments in paleocavities, collapse breccias, paleosols and neptunian dykes that occur in the “Libeccio Antico” represent the peculiar character…
A diagenetic control on the Early Triassic Smithian-Spathian carbon isotopic excursions recorded in the marine settings of the Thaynes Group (Utah, U…
2016
17 pages; International audience; n the aftermath of the end-Permian mass extinction, Early Triassic sediments record some of the largest Phanerozoic carbon isotopic excursions. Among them, a global Smithian-negative carbonate carbon isotope excursion has been identified, followed by an abrupt increase across the Smithian–Spathian boundary (SSB; ~250.8 Myr ago). This chemostratigraphic evolution is associated with palaeontological evidence that indicate a major collapse of terrestrial and marine ecosystems during the Late Smithian. It is commonly assumed that Smithian and Spathian isotopic variations are intimately linked to major perturbations in the exogenic carbon reservoir. We present p…
Is the Anthropocene really worthy of a formal geologic definition?
2014
Scientists are actively debating whether the Anthropocene, the geologic time span (GTS) we are now living in, should be considered a period, epoch, or age in the geologic timescale. The solution is not easy, because the beginning of this GTS is undefined and the end unknown. In fact, there is no agreement on when the Anthropocene began, the proposed dates ranging from the Second World War, when radioactive fallout branded soils and sediments all over the world, to little after the end of the last glacial period, i.e. 11.7 thousand years ago, therefore coinciding with the onset of the Holocene. We are in favour of a concurrence of the Anthropocene with the Holocene, although a major impact …
Shallow ocean oxygen decline during the end-Triassic mass extinction
2022
The end-Triassic mass extinction (ETME) was associated with intensified deep-water anoxia in epicontinental seas and mid-depth waters, yet the absolute oxygenation state in the shallow ocean is uncharacterized. Here we report carbonate-associated iodine data from the peritidal Mount Sparagio section (Southern Italy) that documents the ETME (~ 200 Ma) in the western Tethys. We find a sharp drop in carbonate I/(Ca + Mg) ratios across the extinction horizon and persisting into the Early Jurassic. This records local dissolved oxygen and iodate decline in the near-surface ocean of low-latitude Tethys due to the development of depleted oxygen concentrations. Consequently, during the ETME even sha…
Comment on "Lethally hot temperatures during the Early Triassic greenhouse".
2013
Sun et al . (Reports, 19 October 2012, p. 366) reconstructed Permian to Middle Triassic equatorial seawater temperatures. After correct temporal positioning of their data points, their presumed trends of temperature changes, and hence their assumption of a one-to-one relationship between putative "lethally hot" seawater temperatures and a disputable equatorial "eclipse" of some organisms, are no longer supported by their data.
Die Larven der rhachitomen Amphibien (Amphibia: Temnospondyli; Karbon — Trias) The larvae of rhachitomous amphibia (Amphibia: Temnospondyli; Carbonif…
1974
Basierend auf Untersuchungen anBranchiosaurus, Archegosaurus, Sclerocephalus und anderen Eryopiden wird erstmals eine allerdings nur vorlaufige Charakterisierung der Larven rhachitomer Amphibien versucht. Die Verknocherung des Skelettes beginnt ontogenetisch verhaltnismasig fruh (vermutlich bald nach dem Ausschlupfen) im Schadelbereich, und in ihrem Ablauf sind mehrere deutliche Phasen zu erkennen. Zuerst ossifizieren verschiedene Elemente der Kieferregion (Ober- wie Unterkiefer) und des Gaumens (Pterygoid, Palatinum, Proc. cultriformis). Das dermale Schadeldach bildet sich wesentlich spater, beginnend im medianen Bereich (Nasale bis Postparietale); das Neurokranium bleibt knorpelig. Nodi n…
Le patrimoine linguistique de l’Europe face aux industries de la langue
1986
Efeitos das práticas verdes na lealdade: proposta de um modelo para o segmento hoteleiro colombiano
2021
Resumen El propósito de este estudio fue analizar la incidencia de las prácticas verdes como impulsoras para generar confianza, satisfacción y lealtad en los huéspedes. Para ello, a partir de una muestra de 302 huéspedes de hoteles en Bogotá, Colombia, se estimó un modelo de ecuaciones estructurales a través de la regresión de mínimos cuadrados parciales. Los resultados obtenidos evidencian que las prácticas sostenibles contribuyen al aumento de la confianza y la satisfacción de los huéspedes, y que estas, a su vez, influyen positivamente en su lealtad hacia el hotel. Además, dichos resultados ponen de manifiesto que una comprensión más profunda del perfil de los turistas medioambientalment…