Cretaceous Research最新文献

The mutual relationship and co-occurrence of the tube-dwelling polychaete Tectorotularia hexagona and the oyster Rhynchostreon suborbiculatum in an instance of fluctuating marginal marine environment, represented by the Orlové Sandstone in the Western Carpathians (Pieniny Klippen Belt), is recorded. As a consequence of climate change during the Cenomanian and early Turonian, changes over time in key ecological factors (e.g., decrease in freshwater inflow and increase in temperature and water mass salinity) led to critical trophic alterations in the marginal marine system studied. The environmental change from polyhaline/eutrophic to euhaline/lower nutrient conditions led to a reduction in the pioneer palaeopopulation of R. suborbiculatum, and Tectorotularia hexagona and other stenohaline marine recliners took over the ecological niches originally occupied by the oyster. In this respect, the relationship between T. hexagona and R. suborbiculatum may be considered a Late Cretaceous example of competition between two groups of sessile-benthic recliners. In the present work, two different tube morphologies of T. hexagona from Hôrka are described, and the tube microstructure of this species is documented for the first time. In addition, the material from Hôrka is compared with that from the type locality, Essen in Germany, and ‘Hamulus’ hexagonus and Tectorotularia ‘westfalica’ are considered to constitute one and the same species. The wider ecological and systematic context of this serpulid species is discussed as well.

Five deformed dinosaur eggs are newly discovered from the Upper Cretaceous Jiangjunding Formation in the Laiyang Basin, Shandong Province, China. A new oospecies of Spheroolithidae, Spheroolithus phacelus, was erected based on the spheroid eggs and the developed cone-shaped eggshell unit assemblages. Radial sections of S. phacelus show the inner cone-shaped eggshell units, the middle columnar eggshell units and the outer bush-like eggshell units. Numerous cone-shaped eggshell unit assemblages and large gaps between them are developed in the inner part, columnar eggshell units and small pores emerge in the middle part, and branches of eggshell units appear in the outermost part, forming bush-like microstructures. Spheroolithidae is a typical oofamily of East Asia consisting of Spheroolithus spheroides, S. chiangchiungtingensis, S. quantouensis, S. oosp. and Paraspheroolithus irenensis, which mainly distributed in the Upper Cretaceous of China, South Korea, Japan and Mongolia. The discovery of S. phacelus provides new fossil materials of oogenus Spheroolithus in Spheroolithidae and expands the palaeogeographic distribution of Spheroolithidae in East Asia, which may be eggs of hadrosauroid. The age of these deformed dinosaur eggs could be presumed to be the middle Late Cretaceous (Coniacian–Campanian).

Cretaceous dinosaur and other terrestrial tetrapod fossils are common throughout Guangdong Province (southern China), with the greatest documented concentrations in the Heyuan and Nanxiong basins and the Ganzhou area. Further south, the Sanshui Basin has a continuous Lower Cretaceous-Eocene sequence. Within the Sanshui Basin, abundant ostracod and mollusk fossils have been documented from the Upper Cretaceous sediments, but vertebrae fossils are rare. Here we report four isolated teeth collected from the Maastrichtian of the Sanshui Basin. Although fragmentary, the teeth can be confidently referred to the Tyrannosauroidea. These teeth constitute the first record of large theropods in southern Guangdong and are also the southernmost record of tyrannosauroids in China.

The Upper Tithonian to Lower Berriasian carbonate sequence of the Getic Nappe system was studied near Golubac (eastern Serbia) using rock-magnetic and paleomagnetic methods to verify the age of the magnetization and to correlate magnetostratigraphy with biostratigraphy. A major part of the Dedina section shows the presence of authigenic goethite, hematite and magnetite as carriers of remagnetization. The youngest overprint, residing in goethite, sometimes carrying up to 90 % of natural remanent magnetization, was probably received after 18 Ma. The remagnetization residing in hematite and magnetite, attributed to the late Early Cretaceous collision, was obtained during long normal polarity Chron C34 (118–82 Ma). The mean direction implies a clockwise post-remagnetization rotation by about 57°. The normal (D_n) and reverse (E_r) polarity components, heavily affected by the chemo-remanent magnetization overprint, can be tentatively interpreted in terms of polarity zones. Thus, the obtained data enabled a preliminary identification of M17r to M19n.2n magnetochrons. The correlation of magnetostratigraphy with biostratigraphy of the Dedina section contributes to the stratigraphic framework necessary for the definition of the Berriasian Global Boundary Stratotype Section and Point.

Non-avian maniraptoran eggs are abundant in the Upper Cretaceous of China. Previous studies mainly focused on oviraptorosaur and troodontid eggs which can be classified into the oofamilies Elongatoolithidae and Prismatoolithidae, respectively. Here we report a new possible ootype of dromaeosaurid dinosaur recovered from the Lianhe Formation of the Ganzhou Basin. The new ootaxon, Gannanoolithus yingliangi oogen. et oosp. nov., is remarkable for its symmetrically elliptic shape and two structural layers with an abrupt and straight boundary. It shares a similar elongated shape, interlocked eggshell units, and an angusticanaliculate pore system with those of Deinonychus eggshell-like maniraptoran ootaxa reported from North America, Europe, and East Asia. The new phylogenetic analysis suggests the monophyly of dromaeosaurid and oviraptorosaurian eggs, and troodontid eggs are closely related to bird eggs. Paired eggs of Gannanoolithus might indicate that dromaeosaurid dinosaurs also have paired functional oviducts like oviraptorosaurs and troodontids. In addition, the porosity and EBSD analyses support that these eggs in the mound nests are buried.

The fossil-rich Romualdo Formation (late Aptian/early Albian), Araripe Basin, northeastern Brazil, contains world-renowned Fossillagerstätten characterized by exceptionally preserved fossils. Macroinvertebrates in this formation are primarily represented by mollusks, echinoids, and decapod crustaceans. Mollusk shells are abundant in certain stratigraphic intervals, forming coquinas or shell pavements. Despite recent advances in our understanding of the taxonomy of certain groups, comprehensive taxonomic studies are lacking for almost the entire bivalve fauna. Therefore, a detailed taxonomic analysis is presented here. The described bivalves include four new genera (Araripenomia, Ciceromya, Inversatella, Australoeocallista), and six new species (Araripenomia infirma, Inversatella cearensis, Ciceromya edentulosa, Australoeocallista juazeiroi, Legumen kaririense, and Corbulomima delicata), in addition to Musculus maroimensis, Crassatella maroimensis, “Myrtea” sp. and “Tellina” sp. This bivalve fauna mainly consists of cosmopolitan and endemic brackish/marine genera, with Tethyan affinities. The fauna is not homogeneously distributed in the sedimentary succession of the Romualdo Formation, but is constrained to the third order highstand systems tract. Bivalves recorded from muddy facies are strongly dominated by infaunal and semi-infaunal suspension feeders. Assemblages of the sand-dominated facies, with dense shell accumulations of semi-infaunal to epifaunal byssate and infaunal suspension feeders, were formed under shallow, higher energy conditions. Despite the degree of generic endemicity, the mytilids, anomiids, crassateliids, astartids, tellinids, and corbulids are related to the bivalve fauna of the Early Cretaceous Riachuelo Formation of the Sergipe-Alagoas Basin, as previously demonstrated for the bakevelliids and echinoids. Indeed, the Romualdo bivalve fauna is, in part, a modified and impoverished brackish/marine fauna of the Riachuelo Formation.

Sedimentological and stratigraphical studies in the Cretaceous series of the Tendrara dome led to the discovery of fossiliferous levels in the pre-Cenomanian and Cenomanian deposits, providing significant biostratigraphic, paleoenvironmental, and paleogeographic results. In the SW part of the Tendrara dome, the predominantly terrigenous deposits at the base of the pre-Cenomanian (Dekkar 1 Formation) yielded dinosaur eggshell fragments and charophytes, in particular Clavatoraceans, pointing to the Barremian-Aptian. Above this unit, two beds with fish remains were discovered in the Dekkar 2 Formation and at the base of the Dekkar 3 Formation, respectively. To the NE of the Tendrara dome, a fossiliferous site with diversified benthic fauna and abundant fish remains was discovered in a thin marly unit unconformably overlying the Middle Jurassic basement. Elasmobranch micro-remains indicate a Cenomanian age for this unit. The SW-NE correlations indicate a marked thickness reduction and lateral facies variations, implying a strong asymmetry in the Cretaceous paleogeography of the dome. The first continental and lagoonal basins of the Barremian-Aptian and Albian?-Cenomanian are located in the southern part of the Tendrara dome. The Cenomanian transgression, initiated from the south, gradually covered the dome, depositing reduced coastal plain elasmobranch-rich facies in its northern part. The Tendrara dome constituted a paleogeographic barrier, limiting the first transgressions of the Cenomanian sea. This paleostructure is part of an emerged area (Idrissides High) located between the Tethyan Ocean and the Saharan epicontinental sea.

Cockroach Clypeblattula panda gen. et sp. n. is described from the Lower Cretaceous Laiyang Formation of Shandong Province, China based on a specimen with forewing and pronotum well-preserved. It is characterized by ovoid pronotum with two trapezoid dark stripes, forewing with intercalary space in R with colouration, A with six simple veins, and sparse cross-veins. It is closely related to the Early Cretaceous Pravdupovediac according to colouration of intercalary space in R, but they can be distinguished mainly based on the different wing shapes and the existence of dark macula. The differences between Clypeblattula gen. n., Ocelloblattula, Pseudomantina, Habroblattula and Laiyangia are also briefly discussed. The new genus is another indigenous cockroach of Blattulidae.

Lower Valanginian oyster mass occurrences (OMOs) from the Neuquén Basin of Argentina are analyzed using a multidisciplinary approach, including the description of their sedimentological signature and stratigraphic contacts, assessment of taphonomical attributes, and paleontological and paleoecological characteristics. These OMOs present a wide distribution in the study area, with lateral continuity for at least 2.5 km and up to 12 m thick. They occur within a single stratigraphic interval, constrained in terms of sequence stratigraphy and biostratigraphy. Three stacked tabular OMOs separated by mudstone levels were recorded in all the studied localities. The associated lithofacies point to a mainly outer ramp paleoenvironment, below storm wave base and occasionally disturbed by exceptional, distal storm flows. Internally, the OMOs share a common vertical trend characterized, from base to top, by a gradual increase in oyster abundance and a transition from mainly reclining, disarticulated oysters to articulated, cementing oysters conforming build-ups. Hence, a mainly biogenic origin is proposed, with autobiostromes grading vertically to bioherms. This vertical trend was interpreted in terms of development stages, namely, colonization, expansion, climax and extinction, which were in turn related to specific paleoenvironmental controls. Particularly, the OMOs establishment and development were associated to low sedimentation rates, salinity fluctuations and high nutrient input as a result of high primary productivity. At a larger scale, the overall paleoenvironmental conditions and subtropical geographical position of the basin were detrimental for most reef builders typical of the Cretaceous period (e.g., corals, sponges, rudists), and could have favored oyster proliferation and OMOs development instead.

A new genus with two new species of Micropterigidae, Terncladus lunatus Han, Zhang et Ren gen. et sp. nov. and Terncladus halonatus Han, Zhang et Ren sp. nov., are erected based on three well-preserved specimens in Late Cretaceous Kachin amber. The new genus can be identified by hind wing with veins Sc unforked, no trace of free R, and Rs three-branched. Furthermore, we applied Geometric Morphometric Analyses (GMA) to study 26 species with well-preserved forewings of Micropterigidae and presented the results for the first time. The GMA results confirmed the classification of the new genus and shed light on the differences and diagnoses of the five monophyletic lineages of Micropterigidae. By comparing the geographical distribution and climatic environment characteristics of Micropterigidae in different geological periods, Micropterigidae have a relatively conservative adaptability to the environment during the evolutionary process.