Maastrichtian dinosaurs in SW Transylvania (Romania)

Although the first dinosaur discoveries from the Transylvanian Basin were made at Bărăbanţ near Alba-Iulia as early as the end of the 19^th century, the Latest Cretaceous Transylvanian dwarf dinosaurs gained their worldwide notoriety only after Baron F. Nopcsa reported his first discoveries in the Haţeg Basin. Nopcsa realized the dwarfing tendencies of these dinosaurs and related this tendency to their limited environment, which he called “the Haţeg Island”. In order to defend the pattern he identified, he attempted to outline the spatial extension of this island, as supported by the distribution of illustrative non-marine sedimentary deposits. In this context, he discovered several new localities with dinosaurbearing rocks. Among these, the most important ones are located in the Alba-Iulia area. These faunal assemblages seem to be coeval with those from the Haţeg Basin. The non-marine Maastrichtian deposits from Alba County accumulated after the Late Cretaceous “Laramian” tectogenesis, when a fluvial system evolved in the area of the present-day Carpathians. As a matter of fact, the sediments exposed in Alba County suggest similar environments to those from the Haţeg Basin. In the red mudstones and the channel sandstones of the Şard Formation, several vertebrate teeth and bones have been preserved. In this paleobiota, dinosaurs are well represented by the following taxa: titanosaurian sauropods, the basal hadrosaurid Telmatosaurus transsylvanicus, the euornithopod taxa Zalmoxes shqiperorum and Z. robustus, the nodosaurid ankylosaur Struthiosaurus transylvanicus, as well as various small theropods. Besides dinosaurs, there are crocodilians (Allodaposuchus and Doratodon), turtles, and lizards. Fishes, amphibians, birds, and multituberculate mammals are other vertebrates making up this assemblage. More often than not, the remains are fragmentary, scattered and weathered, except for those preserved within sediments of lacustrine origin.