The present paper outlines the results of a detailed study of calcareous nannofossils and small foraminifera made on Campanian marine deposits from the southwestern part of the Transylvanian Basin, Romania, part of the marine-to-continental transitional Petrești succession that yielded the oldest temporally well-constrained continental vertebrate remains in this area. These results are integrated with new and previously published palynostratigraphic information as well as with novel detrital zircon geochronometry data. All three groups of fossils (calcareous nannofossils, small foraminifera, and palynomorphs) convergently indicate an early to middle Late Campanian age for the marine part of the Petrești section. Based on detrital zircon analyses, the most likely maximum depositional age of the studied deposits is 76 ± 1.7 Ma, thus confirming the age supported by microfossil assemblages. Palaeoenvironmental interpretation of the fossil assemblages recovered from the marine part of the Petrești section suggests that despite their flysch-like facies, these beds were deposited in a continental shelf setting, under suboxic conditions and frequent fluctuations in nutrient supply to the seafloor, but quite stable environmental conditions within the water column. The synthesis of all currently available biostratigraphic and geochronologic data from the Petrești succession suggests a middle-late Late Campanian start for the expansion of the emergent land areas that made up the latest Cretaceous Hațeg Island, earlier than previously accepted dates (Maastrichtian) for this event. Furthermore, it documents the establishment of a diversified continental vertebrate faunal assemblage by the second half of the Late Campanian on these emergent lands while also providing further evidence for a later, post-Campanian arrival of certain iconic Hațeg Island dinosaur groups such as titanosaurs and hadrosauroids. Finally, our data show that kogaionid multituberculate mammals were already members of the earliest known Hațeg Island faunas, extending the fossil record of this group from the Maastrichtian into the later part of the middle Late Campanian.

本文概述了对罗马尼亚特兰西瓦尼亚盆地西南部的坎帕尼亚海洋沉积物中的钙质超微化石和小型有孔虫的详细研究结果，该沉积物是海洋到大陆过渡时期佩特雷什蒂序列的一部分，该序列产生了最古老的时间井。该地区仍存有有限的大陆脊椎动物。这些结果与新的和先前发布的孢粉地层信息以及新的碎屑锆石测时数据相结合。所有三组化石（钙质超微化石、小型有孔虫和孢粉化石）一致表明佩特雷什蒂剖面的海洋部分处于坎帕尼亚晚期早至中期。根据碎屑锆石分析，所研究矿床最有可能的最大沉积年龄为 76 ± 1.7 Ma，从而证实了微体化石组合所支持的年龄。对从彼得雷什蒂剖面海洋部分回收的化石组合的古环境解释表明，尽管它们具有复理石状相，但这些床沉积在大陆架环境中，在缺氧条件和海底养分供应频繁波动的情况下，但相当稳定水柱内的环境条件。对佩特雷什蒂演替中所有当前可用的生物地层学和地质年代学数据的综合表明，构成最新白垩纪哈塞格岛的新兴陆地区域的扩张是在坎帕尼亚晚期中晚期开始的，早于先前接受的该事件的日期（马斯特里赫特阶） 。此外，它记录了坎帕尼亚晚期后半叶在这些新兴土地上建立了多样化的大陆脊椎动物群落，同时也为某些标志性哈塞格岛恐龙群体（例如泰坦龙和鸭嘴龙）在坎帕尼亚晚期之后的到来提供了进一步的证据。最后，我们的数据表明，kogaionid 多瘤哺乳动物已经是已知最早的哈塞格岛动物群的成员，将该类群的化石记录从马斯特里赫特阶延伸到了晚坎帕尼亚中期的后期。