A new concentration lagerstätte for marine vertebrates of Tithonian (Uppermost Jurassic) age in southern Coahuila, Mexico

During our research work in NE Mexico on Late Jurassic sediments containing well preserved vertebrate and invertebrate fossils (e.g., at Aramberri, Nuevo León), we discovered a locality where remnants of marine reptiles of ?Early Tithonian age are concentrated in coquina layers with a thickness of about 1.5 m. Ammonoids, ostreid bivalves, belemnites and wood occur frequently, as well as an abundant and diverse assemblage of marine vertebrates. So far, we identified pliosaurs, plesiosaurs, ichthyosaurs, thalattosuchian crocodilians and two species of fishes. After several excavation campaigns a taxonomic inventory has been established and the taphonomic circumstances can be clarified. We will compare the fossil inventory with that of coeval lagerstätten in southern South America (e.g., Neuquen, Argentina, South Patagonia, Chile) and Europe (e.g., Oxford clay, UK, Solnhofen Plattenkalk, Bavaria) and discuss palaeobiogeographical links of the Gomez Farías assemblage with the faunal realms of the Tethys, Pacific and primordial South Atlantic. In addition, we want to reconstruct the palaeoenvironmental conditions that led to the remarkable fossil concentration at Gomez Farías, in the context of regional and global palaeooceanographic changes during the Late Jurassic and across the J/C boundary based on geochemical investigations. (Kooperationsprojekt: Prof. Dr. Wolfgang Stinnesbeck, Universität Heidelberg, apl Prof. Dr. Eberhard „Dino“ Frey, SMNK, finacial support: DFG).

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