Cretaceous Research最新文献

Taxonomic diversity in the derived tyrannosaurine Daspletosaurus has been hypothesized to represent a variety of evolutionary patterns by different authors. The recent description of D. wilsoni, the third species of this genus, was proposed to support the paraphyly of Daspletosaurus and participation of its species within a single anagenetic lineage terminating at the base of a clade formed by Tyrannosaurus and other gigantic tyrannosaurines (Tarbosaurus, Zhuchengtyrannus). However, a recent reanalysis including additional data has challenged this interpretation, instead recovering Daspletosaurus as a monophyletic sister group to Tyrannosaurus and its closest relatives, characterized by several cladogenetic events. Here we show that incorporating further data and correcting erroneous interpretations of relevant anatomical features overturns this result. Using a novel phylogenetic analysis including additional specimens, we recover a paraphyletic Daspletosaurus, with species of this genus forming successive sister taxa to Tyrannosaurus-line tyrannosaurines. This result facilitates an interpretation of currently recognized Daspletosaurus species as representing a single anagenetic lineage, in agreement with the stratigraphic distribution of relevant specimens and a qualitative analysis of the range of morphological variation observable within D. wilsoni.

High trochospiral architecture is relatively uncommon in rotaliid foraminifera as it is observed in a few species throughout the stratigraphic record of their 100 My history. Such a feature is recorded within the lockhartiniid group, for example in the Paleogene genus Sakesaria, whereas it is not reported from the Cretaceous. We describe two new Late Cretaceous species, Extentaspira pichezziae gen. nov., sp. nov. and Extentaspira pampaloniae sp. nov., displaying high trochospiral test, from the shallow-water facies of the Apennine and Adriatic carbonates platforms of Central and Northeastern Italy. Besides the absence of dimorphism, high trochospiral test architecture suggests an adaptation to an infaunal lifestyle. These occurrences may provide further evidence on the paleo-biogeographic gradient with the nearby Late Cretaceous Pyrenean gulf.

Cretaceous and possibly Paleogene strata, originally defined as the Alter do Chão Formation, are extensively exposed in the Amazonas Basin. While theoretical considerations suggest that the eastern Amazon has been draining into the Atlantic since pre-Miocene times, the limited published field data indicate a significant continental-scale reversal of drainage, transitioning from westward flow during the Cretaceous to the current eastward regional flow. This hypothesis has a significant impact on accepted paleogeographic reconstructions and has implications for the origin of the Amazon River and the associated biotic environments. Nevertheless, the observational database to support that hypothesis is still very scarce. To address this problem, the present study presents data from a basin-transverse profile where the entire stratigraphic succession of Cretaceous and Paleogene ages in the Amazonas Basin is exposed, namely the Jazida da Fazendinha and Alter do Chão formations. Facies analysis of cliff outcrops along the Tapajós River margins, including the type area of the units, reveals associations interpreted as fluvial deposits dominated by sandy bars. Paleocurrents were interpreted from more than 2000 individual measurements of fluvial cross-strata from various stratigraphic levels. The findings indicate that the regional flow direction during the deposition of both units was eastward across the entire basin transect. Integrating our dataset into the existing data on provenance reveals that, unlike the modern Andean-derived system, the primary sources for the Alter do Chão Formation were limited to the Amazon Craton. Our findings offer compelling empirical evidence to support the scenario proposed by previous numerical models. The findings also suggest that the rock record does not support the poorly documented and highly influential model of a significant westward-flowing river in Amazonia during the Cretaceous and the Paleogene.

The South Pyrenean Basin has yielded abundant dinosaur and penecontemporaneous vertebrate fossils, becoming one of the most important areas in Europe for the study of these faunas. The studied isolated theropod teeth from the Western Tremp Syncline (NE Iberia) were recovered from the uppermost Maastrichtian (topmost Arén and Tremp formations). The studies conducted have led to the identification of eight tooth morphotypes, which are referred to cf. Paronychodon, cf. Richardoestesia, an abelisaurid, a dromaeosaurid, and a non-dromaeosaurid paravian. Together with the previously reported troodontid and ornithuromorph, this study increases the known theropod palaeobiodiversity in the area to seven taxa. The latest Maastrichtian theropod fauna of the Western Tremp Syncline is thus composed of a medium to large-sized abelisaurid as well as a high diversity of small-bodied early-branching coelurosaurians and avialans, as seen in other Ibero-Armorican localities. Revision of the literature concerning the theropods of the Ibero-Armorican domain indicates that, although similar theropod groups were present before, during, and after the intra-Maastrichtian faunal turnover (an event constrained to between the early Maastrichtian and the early late Maastrichtian; lower part of C31r to the C30r/C30n reversal), there were changes in the abelisaurid, dromaeosaurid, and large avialan assemblages, as well as in the proportions of indeterminate paravian and cf. Richardoestesia morphotypes, with the presence of troodontids only recorded in post-turnover faunas. These changes suggest that theropods might have been affected by the turnover event. Nevertheless, further studies and more complete specimens could shed more light on the effects of this faunal turnover, and on the affinities and palaeobiodiversity of the latest Cretaceous Ibero-Armorican theropods.

Coprolites (fossil droppings) are common in the Mesozoic fossil record. However, coprolite assemblages from continental settings have more rarely been quantitatively analysed than the marine ones. The excavation of the Berriasian continental Lagerstätte of Angeac-Charente (France) during the last decade has resulted in unearthing a vast number of fossils, including ca. 6000 coprolite specimens. This large collection, accompanied by spatially landmarked depositional data, offers a unique opportunity to assess the organism interactions in an Early Cretaceous freshwater swamp ecosystem. We assign the coprolites to nine morphotypes based on their morphology and contents (using tomography and thin-sections), and to four taphonomic categories. We compare the specimens to other fossil and recent droppings, including newly imaged crocodilian faeces. While the Angeac-Charente biota comprised animals of a range of different ecologies, including waters primary inhabitants (chelonians, crocodylomorphs, actinopterygians) and a variety of dinosaurs, the coprolites, together with other ichnological evidence, such as bite marks, seem to largely illustrate the activity of the crocodylomorphs in this ancient swamp. The assemblage is compared to previously analysed continental Cretaceous copro-assemblages from Europe and North Africa.

The Upper Cretaceous sauropod fossil record from Romania is abundant, mostly originated from the Maastrichtian deposits of the western-southwestern margin of the Transylvanian Basin, and in the Hațeg and Rusca Montană basins. Most specimens were found in isolation or in low degree of association and only few partial skeletons have been reported. The presence of at least four taxa was recently considered, including three defined forms: Magyarosaurus dacus, Paludititan nalatzensis and “Magyarosaurus” hungaricus. However, the phylogenetic affinities of these taxa within Lithostrotia are still under debate. A large sample of appendicular remains, predominantly composed by unpublished specimens, is described here in detail to provide new data about the diversity of the sauropods of the Hațeg Island during the Maastrichtian. All specimens show affinities or are compatible with lithostrotian sauropods, even if the availability of characters of some of them does not allow its attribution to this clade. Five morphotypes for the femora, three to four for the humeri, three for the fibulae, and two for the radii, ulnae, manus, pubes, ischia, tibiae, and pedes are established, supporting the presence of four or five taxa in this domain. A unique partial manus morphology characterized by its extreme gracile metacarpals is reported, only surpassed by an unpublished manus found in the Spanish Lo Hueco fossil-site (late Campanian-early Maastrichtian), suggesting that a titanosaurian lineage with extremely elongated manus inhabited the European realm, in both Hațeg and Ibero-Armorican islands, at the end of the Mesozoic.

Two ice-rafted dropstones were discovered in the Yaojia Formation (early Santonian) of wells Ao14 and F247 in the Songliao Basin, northeastern China. The dropstone from well Ao14 was further studied using computed tomography (CT) scanning, sporopollen, carbon and oxygen isotope, and zircon U–Pb isotope analyses. The results show that the dropstone is composed of quartz monzonite and has an age of 178.0 ± 3.3 Ma. Based on the bedrock age analysis around the Songliao Basin, it is suggested that the dropstone in well Ao14 may have originated from the Zhangguangcai Range. The palynoflora assemblage indicates a mixed survival of cold and warm palynomorphs. The carbon and oxygen isotope compositions of the synsedimentary calcareous clasts surrounding the dropstone exhibit obvious negative biases, suggesting that glacier meltwater flowed into the paleo-lake, probably due to the significant topographic height difference between the Songliao Basin and adjacent areas during the early Santonian. Additionally, it can be inferred that coastal mountains formed in the Zhangguangcai Range area, which is located southeast of the Songliao Basin, and the dropstones derived from this region. During the cold season, the dropstones may be transported to the edge of Songliao Lake by avalanche and mixed with carbonate debris. As the seasons changed, the lake ice broke into pieces and carrying the dropstones and carbonate debris into the deep lake area. The present research provides direct evidence of a brief global cold event and the presence of high mountains in the southeastern Songliao Basin during the early Santonian in the Cretaceous greenhouse world.

A turtle carapace, identified as Algorachelus cf. peregrina (Pleurodira, Pelomedusoides, Bothremydidae), is reported here from the shallow marine deposits of the Boundary Marls Unit (Utrillas Group), in Estercuel (Teruel Province, northeastern Spain). These levels are identified as deposited during the Lower to Upper Cretaceous transition (late Albian to earliest Cenomanian). This is the oldest record of a bothremydid turtle in Laurasia, documenting that the first dispersal of pelomedusoid turtles from Gondwana to Laurasia occurred earlier than previously identified, most probably in the Early Cretaceous. Pleurodiran turtles always require warm climatic conditions and are mainly freshwater forms. This dispersal was favored by climate change (global warming) that began in the Albian, as well as by the habitat change of the Algorachelus lineage from freshwater to coastal marine environments.

An adult male of †Burmecaelinus armis Uchida, Husemann and Kotthoff, 2023, and a newly identified genus and species †Moban zhengzhemini gen. et sp. nov., are reported based on two well preserved adult specimens from mid-Cretaceous Burmese amber. †M. zhengzhemini gen. et sp. nov. can be distinguished by following characters: body with irregular small dark spots; pronotum is in uniform width, with dispersed shallow dents and two distinct transverse sulci, posterior angle is protruding forward; posterior thoracic process is shark-tooth shaped; pronotal disc without four longitudinal carinae; tip of apical spurs on metatibia not curved. The morphological diagnosis of the family †Burmecaelidae was emended, and the posterior thoracic process of adult †Burmecaelidae species is possibly specialized scutellum. We proposed a hypothesis that this extinct family was a sister group of Tridactyloidea and species of †Burmecaelidae lived in humid environment near water and had affinity for wet and semi-aquatic habitats.