Search results for "Extinction"
showing 10 items of 458 documents
Mercury contents and isotope ratios from diverse depositional environments across the Triassic–Jurassic Boundary: Towards a more robust mercury proxy…
2021
Abstract Mercury is gaining prominence as a proxy for large igneous province (LIP) volcanism in the sedimentary record. Despite temporal overlap between some mass extinctions and LIPs, the precise timing of magmatism relative to major ecological and environmental change is difficult to untangle, especially in marine settings. Changes in the relative contents of Hg in sedimentary rocks through time, or ‘Hg anomalies’, can help resolve the timing of LIP activity and marine extinctions. However, major questions remain unanswered about the fidelity of Hg as a proxy for LIP magmatism. In particular, depositional (e.g., redox) and post-depositional (e.g., oxidative weathering) processes can affec…
Plant fossil record and survival analyses
2012
Cascales-Minana, B. & Cleal, C.J. 2011: Plant fossil record and survival analyses. Lethaia, Vol. 45, pp. 71–82. Survival analysis is a classic palaeobiological method widely used on the animal fossil record. This study reports the first application of survivorship analyses on the plant fossil record from a global viewpoint and provides a new comparative approach of this methodology. The results reveal three important plant extinction events in the history of plant life at a global scale. The results also clearly suggest that the origination events are more intensive than extinction processes and that the origination moment of several lineages of vascular plants is an important factor that c…
Trends and patterns in the evolution of vascular plants: macroevolutionary implications of a multilevel taxonomic analysis
2010
Cascales-Minana, B., Munoz-Bertomeu, J., Ros, R., Segura, J. 2010: Trends and patterns in the evolution of vascular plants: macroevolutionary implications of a multilevel taxonomic analysis. Lethaia, 10.1111/j.1502-3931.2009.00212.x Studying the macroevolutionary patterns of vascular plants from the Silurian to the present-day provides a global record of plant life history. Evolutionary rates (origination, extinction and diversification) for families, orders, classes and divisions were analysed, as was abundance and richness for 21 time intervals. An accumulative analysis, based on the total plant fossil record, the accumulated extinctions and relative diversity, was also carried out. The d…
Conodonts versus Triassic Climatic and Eustatic Changes
2015
Kılıç, Ali Murat (Balikesir Author)
Positive Sulfate Sulfur Isotope Excursion Indicates Large-Scale Pyrite Burial and Marine Anoxia during the End–Triassic Mass Extinction
2020
The late Rhaetian–early Hettangian transition is characterised by the emplacement of Central Atlantic magmatic province and associated climatic effects, coincident with a severe biotic crisis (~201.5 Ma). The oxygen deficiency in the ocean realm is possibly linked to this significant loss in marine biodiversity. However, direct evidence of contemporaneous development of marine anoxia on a global scale has been lacking and the relationship between oxygen and extinction is unclear. Here we report carbonate-associated sulfate δ34S data from three sections across the Late Triassic–Early Jurassic transition. We find synchronous large positive δ34S shifts with a magnitude of >10‰ in the latest…
Bivalves and evolutionary resilience: Old skills and new strategies to recover from the P/T and T/J extinction events
2011
Diversity dynamics among bivalves during the Triassic and Early Jurassic provides the opportunity to analyse the recovery patterns after two mass extinctions: Permian/Triassic and Triassic/Jurassic (T/J). The results presented here are based on a newly compiled worldwide genus-level database and are contrasted to the main morphological characters of the different taxonomical (orders and their constituent families and genera) and ecological groups. Many of such morphological characters are innovations appearing during the time span considered. Diversity and evolutionary rates were assessed and compared between these groups. During the Early Triassic there was a slow recovery, dominated by ep…
A late Permian ichthyofauna from the Zechstein Basin, Lithuania-Latvia Region
2019
AbstractThe late Permian is a transformative time, which ended in one of the most significant extinction events in Earth’s history. Fish assemblages are a major component of marine foods webs. The macroevolution and biogeographic patterns of late Permian fish are currently insufficiently known. In this contribution, the late Permian fish fauna from Kūmas quarry (southern Latvia) is described for the first time. As a result, the studied late Permian Latvian assemblage consisted of isolated chondrichthyan teeth ofHelodussp., ?Acrodussp., ?Omanoselachesp. and euselachian type dermal denticles as well as many osteichthyan scales of the Haplolepidae and Elonichthydae; numerous teeth ofPalaeonisc…
David Malcolm Raup (1933-2015) at the starting point of a new paradigm for Palaeontology
2020
This is a tribute to the late David Malcolm Raup, one of the major palaeontologists of the second half of the 20 th century. In addition, it is a critical review of his outstanding contributions, mainly in the field of theoretical palaeontology: quantitative modelling, the introduction of probabilistic methods in palaeontology, as well as his great imagination to use techniques from other fields, such as insurance actuary. After a general outline of his youth, I present a general depiction of the main topics of his research as a palaeobiologist: morphology, the structure of the fossil record, evolution, and extinction. He covered areas ranging from the theoretical morphology of coiled shell…
New insights into the reading of Paleozoic plant fossil record discontinuities
2011
Studying the discontinuity patterns of Paleozoic vascular plants provides a global vision of these key events from the multivariate methods viewpoint. Non-metric multidimensional scaling, detrended correspondence analysis and cluster analysis have been employed together with a set of diversity and abundance measures and an evaluation of the geologic constraints from the plant fossil record data. The results reveal four clear significant discontinuities in terms of taxonomic composition and record representativeness during the early-middle Devonian, Devonian–Carboniferous, Mississippian–Pennsylvanian and early-late Permian. Due to the controversial character of the plant fossil record data a…
Adaptation to environmental changes: communities need more time than species
1998
Effects of environmental changes on communities and on species have been studied with two different types of animals: mammals and conodonts. This analysis was conducted on mammals from the ’Ubeidiya Sequence (Israel) dated to the Lower Pleistocene, and on conodonts from the quarry of Coumiac (France) dated to the Frasnian/Famennian boundary (Devonian). The main result of the analysis is that an ecological event can be subdivided. First of all there is a change in the environment that corresponds to a physical signal, the species react to this change, and afterwards the communities respond. Thus, a delay in time can be observed between the reaction of the species and the reaction of the comm…