'X' marks the spot! Sedimentological, geochemical and palaeontological investigations of Upper Cretaceous (Maastrichtian) vertebrate fossil localities from the Valioara valley (Densus-Ciula Formation, Hateg Basin, Romania)

At the beginning of the 20th century, the Croatian-Hungarian palaeontologist Ottokar Kadic discovered a rich Late Cretaceous vertebrate assemblage around Valioara in the Hateg Basin, including fossils of several dinosaurs and the lectotype of the eusuchian Allodaposuchus. These fossils were collected from seven main localities and have been housed in the collections of the Mining and Geological Survey of Hungary. However, the collection was mixed afterWorldWar II, and this unprovenanced material currently cannot be used for palaeoecological investigations. Nevertheless, the map marking the location of Kadic's sites has been recently uncovered, showing the positions of the fossiliferous localities, which allows matching these with the historically collected specimens using geochemistry. Based on Kadic's map, we georeferenced, relocated, and re-excavated these vertebrate-bearing outcrops, and documented their sedimentological context. Detailed stratigraphical investigations of the exposed successions indicate that this Valioara material represents one of the oldest (earliest Maastrichtian) Late Cretaceous faunal assemblages known from the Hateg Basin. The vertebrate remains collected during our new excavations around Valioara represent turtles (Kallokibotion), crocodyliforms (Allodaposuchus, Doratodon, 'Theriosuchus', Acynodon), dinosaurs (Zalmoxes, Telmatosaurus, titanosaurs, theropods), and mammals. In order to determine potential geochemical differences among the sites, we selected several specimens with recorded stratigraphic position, measured their trace element compositions, and used these as independent proxies to assess the probable stratigraphic origin of the historical vertebrate fossils. Our detailed sedimentological, geochemical and palaeontological investigations around Valioara contribute to a deeper understanding of the distribution, evolution and palaeoecology of the Hateg vertebrate faunas during the latest Cretaceous. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In the early 20th century, Kadic discovered a Late Cretaceous vertebrate assemblage in Valioara, Hateg Basin. The fossils were georeferenced, relocated, and re-excavated based on Kadic's map, revealing one of the oldest faunal assemblages in the Hateg Basin. The fossils include turtles, crocodyliforms, dinosaurs, and mammals.