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[dinosaur] Late Triassic islands (with dinosaurs) in England + Early Cretaceous Crato Formation paleoenvironment, Brazil




Ben Creisler
bcreisler@gmail.com

Some recent papers:


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Free pdf:

Jack Lovegrove, Andrew J. Newell, David I. Whiteside & Michael J. Benton (2021)
Testing the relationship between marine transgression and evolving island palaeogeography using 3D GIS: an example from the Late Triassic of SW England.
Journal of the Geological Society jgs2020-158.
doi: https://doi.org/10.1144/jgs2020-158
https://pubs.geoscienceworld.org/jgs/article-abstract/doi/10.1144/jgs2020-158/594153/Testing-the-relationship-between-marine

Free pdf:
https://cpb-eu-w2.wpmucdn.com/blogs.bristol.ac.uk/dist/1/555/files/2021/02/2021Lovegrove.pdf


The Rhaetian transgression marked a major change in landscape. The Permian and Triassic had been a time of terrestrial conditions across Europe, including much of mainland UK, as well as the North Sea and Irish Sea, represented by red bed clastic successions. Seas flooded across Europe at 205.7âMa and the shift from terrestrial to marine environments is marked in the UK by the switch from the red beds of the Mercia Mudstone Group to the black mudstones and shelly limestones and sandstones of the Penarth Group. The area around Bristol was marked by a complex landscape in which an archipelago of islands of Carboniferous limestone was formed in the new shallow seas. The application of new methods in geographical information systems allows a detailed exploration of a number of conformable surfaces, the unconformity between the underlying Paleozoic rocks and the overlying Mesozoic strata, as well as levels within the latest Triassic sediments, marking the advance of the sea and interactions with the coeval tectonics, which caused some islands to rise and some basins to descend. The new geographical information system models show a sequence of palaeogeographical reconstructions of the archipelago and relate this to the island tetrapod faunas, which show strong evidence of the speciesâarea effect.

Supplementary material: Supplementary tables S1-S6 and 2D island map GIS files are available at https://doi.org/10.6084/m9.figshare.c.5273256

News:

Pioneering prehistoric landscape reconstruction reveals early dinosaurs lived on tropical islands

https://www.bristol.ac.uk/news/2021/february/prehistoric-landscape-reconstruction.html

https://phys.org/news/2021-02-prehistoric-landscape-reconstruction-reveals-early.html

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Alexandre Cunha Ribeiro, Guilherme Cunha Ribeiro, Filipe Giovanini VarejÃo, Leandro DÃnis Battirola, Edlley Max Pessoa, Marcello GuimarÃes SimÃes, Lucas VerÃssimo Warren, Claudio Riccomini & Francisco Josà Poyato-Ariza (2021)
Towards an actualistic view of the Crato Konservat-LagerstÃtte paleoenvironment: A new hypothesis as an Early Cretaceous (Aptian) equatorial and semi-arid wetland.
Earth-Science Reviews 103573
doi: https://doi.org/10.1016/j.earscirev.2021.103573
https://www.sciencedirect.com/science/article/abs/pii/S0012825221000726



An alternative hypothesis concerning the paleoecological and paleoenvironmental depositional conditions of the Crato Konservat-LagerstÃtte (CKL), Crato Formation, Aptian, NE Brazil, one of the most extraordinary Gondwana fossil sites, is proposed. Following an actualistic approach, the ecology of extant relatives of the most abundant and diverse fossil groups recorded in the CKL (i.e., vascular plants, arthropods, fishes, and tetrapods) is considered. Data is based on an extensive literature review followed by a re-examination of recently collected fossils. This approach allowed a detailed appraisal of the stratigraphic/ecological distribution of the main fossil groups preserved in the CKL. Plant and animal groups are recorded in three main stratigraphic intervals, named Intervals IâIII in ascending order. Most fossils are to be considered autochthonous to parautochthonous and have been preserved in distinct stages of base-level fluctuations within a shallow lacustrine depositional system, subject to periodic flooding in large, depressed areas. Exceptional preservation in such environments was mediated by microbially-induced processes (i.e., microbial mat entombment), mostly in the coastal areas of the alkaline lake. Based on the distinct sedimentary facies and autecological attributes of dominant paleo-bioindicators, a new paleoenvironmental model for the CKL is proposed, encompassing a seasonal, semi-arid, shallow lacustrine wetland. Faunal and floral content were ecologically arranged in long-lasting aquatic zones, surrounded by periodically flooded mesophytic ecotones and outer xeric habitats, as in the modern alkaline lake Chad in Africa. Our data show the relevance of multiproxy analyses (i.e., paleontological, sedimentological, geochemical, and stratigraphic) of exceptional fossil sites for assessing paleoenvironmental conditions in depositional settings subject to continuous base-level changes, such as those existing in complex, present-day wetland ecosystems. The recognition of key parameters in ancient wetlands is of great importance concerning the formation of non-marine Konservat-LagerstÃtten in the geological record.

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