Cretaceous Research最新文献

The Dipsocoromorpha is a small modern heteropteran infraorder, with some fossils documented in Mesozoic amber in recent years. We herein report a new remarkable specimen trapped in mid-Cretaceous Kachin amber, which can be attributed to Dipsocoromorpha: Schizopteridae. Kuanzuia cavanii gen. et sp. nov. is erected for the new specimen on the basis of the following unique autapomorphic characteristics amongst known dipsocoromorphans: pronotal second and third lobes completely fused together and embowed, metafemora nearly triangular in lateral view and with one row of c. 20 strong ventral spines, and metatibiae greatly curved at about its 2/3 length. Mesozoic dipsocoromorphan fossils reported in America, Lebanon, France and Myanmar provide paleontological evidences that this ancient heteropteran insect lineage had probably been distributed worldwide at latest in the Early to mid-Cretaceous. Our new finding further indicates that compared to their modern descendants, early dipsocoromorphans in the late Mesozoic were flourishing and also likely with high morphological disparity.

Stromatolites are organo-sedimentary structures, internally laminated, which grow attached to the substrate. This lamination mirrors the dynamic interaction of environmental and biological factors where its formation takes place. However, some stromatolites from the Yacoraite Formation, from Amblayo locality, in northwestern Argentina, present an unconventional internal structure characterized by bilateral symmetry, where the development of lamination extends towards both sides of an imaginary plane.

This contribution reports a multi-scale analysis of these particular stromatolites, with the aim of determining the extent to which environmental factors have influenced their internal structure. In addition to this, a sequence of stages that gave rise to these organo-sedimentary structures will be proposed.

Results suggest a microbialitic growth by in-situ biologically induced, carbonate precipitation, which was carried out in a shallow intertidal environment with good luminosity and significant sedimentary input. However, the stromatolitic growth occurred over two stages, interrupted by a stochastic event that generated a overturning of the structure, providing a new colonizing surface for growth of microorganisms and resulting in a bilateral internal structure.

The characterization of these stages, including the overturning of the structure, not only provides a highly accurate proxy for reconstructing punctual environmental conditions of the Yacoraite Formation, but also opens up a field of discussion focused on the resilience and recolonization capacity of stromatolite-producing microorganisms after stochastic events.

Chilinia is an extinct genus of cycads, established by Li and Ye in 1964 based on leaf fossils from the Lower Cretaceous in Jilin Province, China. Morphologically, the genus Chilinia closely resembles Ctenis, another cycad foliage genus, in having pinnately divided leaves with laterally inserted pinnae on the rachis and reticulate venation but differs mainly from the latter in having toothed or irregularly lobed rather than entire-margined pinnae. Fossil records show that up to now, nine species of Chilinia have been reported worldwide, representing an index fossil plant in the Jurassic to Early Cretaceous. In this study, we present a comprehensive overview of all reported Chilinia fossils from a systematic palaeobotanical perspective. Fossil records indicate that Chilinia mainly occurred in the middle–high latitudes of the northern and southern hemispheres in Pangea from the Middle Jurassic to Middle Cretaceous. Combined evidence from the morphology of Chilinia and its floral patterns suggests that the genus probably lived in humid warm-temperate palaeoclimatic conditions with brief seasonal variations.

The jaws of cephalopods, ammonites and especially coleoids, are rarely met in fossil state. The localities with diversified jaws, belonging to various groups of fossil cephalopods are even less common. We describe a diversified complex of cephalopod jaws from the upper Cenomanian–middle Turonian of Northern Siberia, which include the upper and lower jaws of Placenticeras ammonites (the oldest placenticeratid jaws known to date) and large-sized jaws of octobrachian coleoids. Although the lower jaws of Placenticeras belong to the aptychus type of ammonoid jaw apparatuses, they are characterized by the thickening of an inner organic layer in their anterior part, with a shape resembling a calcified conchorhynch known in the anterior portion of the lower jaws of Mesozoic nautilids and lytoceratid and phylloceratid ammonoids. The presence a conchorhynch-like structure supports the assumption that the feeding function in placenticeratid lower jaws most likely prevailed over the protective one. The upper jaws of Placenticeras show structure, typical for the jaws of aptychophoran ammonites: an inner lamella, divided into two wings, and a pointed outer lamella. Large-sized upper jaws of octobrachian coleoids demonstrate close affinities with the jaws of Octopoda suggesting that they could have belonged to representatives of this order, probably to large-sized gladius-bearing teudopseins. Judging by the jaws' size, both ammonites and octobrachians, which inhabited the marine basin in the Northern Siberia, were characterized by large body size. The cephalopod assemblage remained unchanged throughout the end of the Cenomanian and the first half of the Turonian.

Late Cretaceous-Early Palaeocene geo-climatic events played an important role in the diversification of the modern ichthyofauna. Lepisosteiformes and Siluriformes are two diverse clades of freshwater fishes, poorly known from India in this time interval. Their fossil record documents their early diversification and can be used to reconstruct palaeobiogeographic relationships among the continental masses during the Late Mesozoic. Indeed, the Cretaceous-Palaeocene is an exceptional time span for the Indian plate as it underwent a primary spatial reorganisation and remarkable geologic and climatic changes with extensive outpouring of the Deccan basaltic magma. Field investigation in a Deccan sedimentary sequence at Kisalpuri, Central India has yielded new, rich, and taxonomically important fossil material of Lepisosteiformes (Lepisosteus indicus, Lepisosteidae) and Siluriformes (Siluriformes indet.), which significantly improves their Cretaceous-Palaeocene fossil record from the Indian subcontinent. These fish lived in freshwater environments such as large rivers, lakes, and coastal areas. Their presence along with other aquatic biotic elements suggests that the Kisalpuri was an abundant aquatic ecosystem rich in nutrients, which attracted a diverse range of organisms to live together with fish. Biostratigraphically, these fishes first emerged in the Late Cretaceous-Early Palaeocene on the Indian subcontinent, and later, they spread to other parts of subcontinent throughout the Cenozoic. Their earliest intra-continental distribution was controlled by the palaeodrainage network influenced by the volcanic flows of the Deccan traps. Their inter-continental palaeobiogeographic distribution was broadly controlled by the sequential break-up of Pangaea. There appear to be close palaeobiogeographic linkages between South America and India during the Cretaceous-Palaeocene era based on the similarity between the Lepisosteiformes and Siluriformes remnants from India and those reported from the Upper Cretaceous of the Bauru Group, Brazil.

The Gobi Desert of southern Mongolia is home to an incredibly rich record of dinosaurs and other vertebrate fossils from the latest Cretaceous Period. Together, more than a dozen sites in several basins have produced one of the richest palaeofaunas known from this interval anywhere in the world. Most of this diversity has been recovered from the fluvial deposits of the Nemegt Formation. Despite historic and ongoing research in southern Mongolia, accurate maps and geological data for the main fossil sites are still lacking, limiting our ability to investigate how local palaeoecological dynamics influenced Nemegt taxa, their geographic distribution, and their evolutionary patterns. One of these sites, Guriliin Tsav, has produced more than a hundred significant fossil specimens to date, but still remains one of the lesser known Nemegt localities. In part this is because many expeditions have instead focused on the nearby Bügiin Tsav, one of the largest and richest localities for the Nemegt Formation. To address this gap, a project was initiated in 2018 to produce a high-resolution topographic map of Guriliin Tsav using Unmanned Aerial Vehicles (UAV), and consequently, to plot the geographic and stratigraphic distributions of palaeontological resources on this map. In so doing, we also collected stratigraphic and taphonomic data from the area, allowing for the first detailed palaeoecological interpretation of Guriliin Tsav and a comparison with other localities of southern Mongolia. Here we present the results of this project, and also discuss new topographic and stratigraphic data from Bügiin Tsav. This sheds new light into the temporal and geographic distribution of vertebrate taxa in the latest Cretaceous of Mongolia.

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.