Cretaceous Research最新文献

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.

Proraphidia anisomorpha sp. nov., a new species of snakefly (Insecta: Raphidioptera: Mesoraphidiidae), is described from the Lower Cretaceous Laiyang Formation, Shandong, China. This is the first discovery of Proraphidia from the Laiyang Formation, thus extending the geographical range of this genus. P. anisomorpha sp. nov. is different from other species of Proraphidia according to its unique branching structure and small wing size. The palaeogeographic distribution of Proraphidia is also summarized.

The Bauru Group (Campanian–Maastrichtian) has one of the richest fossil records of Cretaceous in South America. All dinosaur fossils from this unit were assigned to Saurischia, most of them poorly preserved. We present the histological and taphonomic analysis of a dinosaur dorsal rib fragment from the Marília Formation in the western state of Minas Gerais. Thin sections were prepared to describe the microstructures of the bone tissue and the fossilization processes involved in preserving the specimen. An elemental analysis was also performed to verify the chemical composition of the fossil and rock matrix. Haversian bone was identified in the rib cortex, and no growth marks or an external fundamental system were found. The rib probably belonged to a saurischian dinosaur because of its plank shape and elliptical cross-section. Hypotheses regarding taphonomic processes were inferred. An extended period of subaerial exposure, followed by high-energy transport, was interpreted due to extensive fractures and signs of abrasion on the outer surface of the bone. Pyrite pseudomorphs (framboids) indicate that the bone was deposited in a reductive environment. After burial, the rapid precipitation of calcite and alkaline stability allowed the preservation of apatite during the recrystallization phase. The manganese hydroxides were deposited on apatite crystals during early diagenesis. We concluded that the fossil rib presented a common taphonomic bias identified among vertebrate fossils of the Bauru Group, which is associated with the exposure of the bones to arid and semiarid climates, their transport into the depositional environments and pedogenetic influence during fossil diagenesis.

The family Osmylidae is an archaic group of Neuroptera and has rich fossil records. Here we present a review of Osmylidae from the mid-Cretaceous amber of northern Myanmar. We describe a new species: Nuddsia simplex sp. nov., and a new genus with one new species: Myanmarosmylus wintertoni gen. et sp. nov. Supplementary description of Nuddsia magnifica (Myskowiak et al., 2016) is also provided, with the male genitalia described for the first time. Myanmarosmylus wintertoni gen. et sp. nov. represents the first record of the subfamily Protosmylinae from the Cretaceous amber. Our new findings provide important evidence for understanding the palaeodiversity and morphology of the Cretaceous lance lacewings.

The oldest salpingid beetle is discovered from the mid-Cretaceous Myanmar amber: Cretoprostominia myanmarensis Jiang, Liu and Chen gen. et. sp. nov. The new genus is most similar to the extant genus Prostominia Reitter, 1889 and differs from the latter by the narrowly separated procoxae. The new discovery enriches our knowledge of the evolutionary history of the family Salpingidae.