Early Cretaceous Research Articles

Haliskia peterseni, a new anhanguerian pterosaur from the late Early Cretaceous of Australia

Pterosaur remains have been reported from every continent; however, pterosaur skeletons remain rare. A new pterosaur is presented here, Haliskia peterseni gen. et sp. nov., constituting the most complete specimen from Australia from the upper Albian Toolebuc Formation of the Eromanga Basin (Queensland, Australia). A combination of features, including the presence of a premaxillary crest and curved teeth, and the morphology of the scapulocoracoid, support its referral to Anhangueria. Haliskia can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the 4th and 5th tooth pairs are smaller than the 3rd and 6th, and the 2nd and 5th alveoli are smaller than 3–4 and 6–8. Moreover, the hyoid is 70% the total length of the mandible. The phylogenetic analyses presented here place Haliskia within Anhangueria. In one analysis, Haliskia and Ferrodraco are resolved as sister taxa, with Tropeognathus mesembrinus sister to that clade. The other resolves Haliskia, Mythunga and Ferrodraco in a polytomy within Tropeognathinae. The new Australian pterosaur attests to the success of Anhangueria during the latest Early Cretaceous and suggests that the Australian forms were more taxonomically diverse and palaeobiogeographically complex than previously recognized.

In situ U–Pb dating of garnet, vesuvianite, and scheelite from the Nanyangtian tungsten deposit reveals an Early Cretaceous W mineralization event in Southeast Yunnan, China

The Nanyangtian W deposit, located in the Laojunshan district, is the largest W deposit in southeastern Yunnan, China. However, before that, the mineralization age of this deposit is still controversial, since the absence of suitable dating minerals and methods. In this study, garnet and vesuvianite, the typical skarn minerals, and scheelite, the dominant ore mineral at Nanyangtian, were selected for LA–ICP–MS U–Pb dating to directly constrain the ages of skarn and W mineralization. As a result, two layered garnet samples together yield a Tera–Wasserburg lower intercept age of 203.2 ± 8.7 Ma, whereas two vein-type vesuvianite samples yield ages of 144.4 ± 3.7 Ma and 145.9 ± 3.1 Ma, identical within error to the ages of 141.5 ± 7.2–145.5 ± 2.9 Ma obtained from micro-disseminated and veinlet-like scheelite. The above dating results and the geological observations that ore-barren layered garnet cut by later quartz–scheelite–(garnet)–(vesuvianite) hydrothermal veins suggest two stages of skarnization in the Nanyangtian deposit (ca. 203 Ma and ca. 141–146 Ma, respectively), whereas the W mineralization occurred during ca. 141–146 Ma. It is inferred that the age of ∼203 Ma is related to Indosinian regional metamorphism and associated migmatization-hydrothermal activity. Nevertheless, the ages of 141–146 Ma, obviously older than those of the adjacent Laojunshan granitic pluton (∼83–97 Ma) and its associated Dulong Sn–Zn polymetallic deposit (∼82–96 Ma), are possibly attributable to another unrevealed magmatic-hydrothermal system at depth, as a result of Paleo-Pacific subduction during the Early Cretaceous period. A two-period superimposed mineralization model is thus proposed at Nanyangtian. Based on all reported age data, four major magmatic-metallogenic episodes ranging from ca. 445–410 Ma, 215–203 Ma, 152–140 Ma to 100–75 Ma have been determined in the Laojunshan district.

A taxonomic note on the tapejarid pterosaurs from the Pterosaur Graveyard site (Caiuá Group, ?Early Cretaceous of Southern Brazil): evidence for the presence of two species

ABSTRACT The Caiuá Group (Cretaceous of Southern Brazil) is famous for the Pterosaur Graveyard site, a location that has yielded hundreds of tapejarid specimens, among other taxa. Previous works had already presented various specimens of Pterosaur Graveyard (PG) tapejarids, reporting on several cranial elements showing substantial anatomical variations. These variations have been interpreted as intraspecific in nature, with all tapejarid specimens having been attributed to a single species, Caiuajara dobruskii. The present contribution reassesses the morphological diversity found in PG tapejarid specimens. Evidence is provided for the interpretation of several variations as interspecific in nature, particularly regarding rostral, palatal, occipital, and third cervical morphology. The present data indicate a segregation of the PG tapejarid specimens between two consistent morphotypes, which are interpreted here as two distinct, coexisting species: Caiuajara dobruskii and Torukjara bandeirae gen. et sp. nov.

A turtle from northeastern Spain reveals that the dispersal of Pelomedusoides from Gondwana to Laurasia probably occurred in the Early Cretaceous

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.

Evidence of theropod dinosaurs in the upper hauterivian–lower barremian of Jebel Kebar (central Tunisia): Paleobiogeographic implications

The fossil record of Mesozoic dinosaurs in Tunisia has long been thought to be restricted exclusively to the southern part of the country. Although tidal and continental environments have been recognized within Cretaceous formations in central Tunisia based on sedimentological analyses, no skeletal remains ascribable to dinosaurs have been found in these deposits. The hypothesis of a possible land connection between central and southern Tunisia during the Early Cretaceous has not been previously explored due to notable lateral variations in facies, marked by the recurrent occurrence of shallow marine deposits separating these domains. The vertebrate ichnological record in the Central Tunisian Atlas was limited to isolated tridactyl footprints exclusively observed in the Albian Kebar Formation. Here, we report the first dinosaur tracks from the pre-Albian Cretaceous (upper Hauterivian–lower Barremian) of central Tunisia. These tracks consist of large tridactyl footprints left behind by medium to large-sized non-avian theropods. They occur within an extensively fractured dolostone bed and exhibit poor morphological preservation. Besides their dimensions, some tracks show morphological features, including broad digit impressions with some terminating in sharp claw traces, low to moderate mesaxony, and a wide divarication angle of the outer digits, reminiscent of the ichnogenus Megalosauripus. However, due to their poor state of preservation and limited number, we refrain from assigning these tracks to the ichnogeneric level and refer to them as indeterminate eubrontid footprints. The occurrence of theropod tracks in the Lower Cretaceous of central Tunisia confirms the sedimentology-based hypotheses about a temporal emergence of parts of this area, which was probably related to tectonic events. We compile previous biostratigraphic, sedimentological, and paleoichnological data to suggest possible periodic connections between the mainland in the south and the tidal flat environments within the central basins. Additionally, two possible scenarios regarding the biogeographic implications of the Jebel Kebar tracks are discussed. The first scenario suggests that a Gondwanan theropod fauna would have been exploring and residing in newly emerged regions of higher latitudes, whereas the alternative scenario posits the existence of a paleogeographic link between the northern margin of Gondwana and Adria, which would have allowed an interchange of theropod faunas between the two landmasses at least in the early Barremian.

Understanding the burial history and the hydrocarbon potential of the late Paleozoic Claromecó foreland Basin (Southwestern Gondwana, Argentina) by combining organic geochemistry, organic petrology, and thermal modeling

The Claromecó foreland Basin (Carboniferous–Permian; southern Buenos Aires province, Argentina) is key to understanding the paleotectonic evolution of the southwestern Gondwana margin and is relevant to energy resource exploration. This study reconstructs the thermal and burial history of the Claromecó Basin by integrating geochemical data, organic petrology, and thermal modeling techniques. Cores samples of the Tunas Formation (Pillahuincó Group, Early Permian) were studied. A 1D thermal model was constructed, calibrated with vitrinite reflectance measurements (VRo %), and corroborated with fluid inclusion and apatite fission track data from previous studies. Rock-Eval pyrolysis results show TOC% values ranging from 0.13 to 60.35 wt%. The Hydrogen index (HI < 50 mg HC/g TOC) and Oxygen index (OI < 50 mg CO2/g TOC) indicate the dominance of Type III and Type IV kerogens, most likely resulting from the thermal maturation of an original Type III kerogen. Petrologic observations confirm the presence of macerals from the inertinite group, as well as minor amounts of vitrinite and liptinite. The Tmax displays a temperature range mostly from 460 to 610 °C. The VRo % values range from 1.5 to 2.0%. Geochemical data combined with VRo % measurements confirm a late catagenesis to metagenesis stage within the wet to dry gas window for coals and organic-rich strata.In order to constrain the thermal evolution of the basin infill, different scenarios were tested by varying the heat flow and the missing section thickness associated with the uplift and erosion of the basin (Permian–Cenozoic unconformity). The best calibration results were obtained with an erosion thickness of 3000 up to 4200 m and paleo heat flow peaks of either 60 or 80 mW/m2 during the Lower Permian–Lower Cretaceous. The Tunas Formation was deposited and buried during the Permian–Triassic (Gondwanides Orogeny phase), reaching a maximum temperature of 180 °C. The results obtained by combining geochemical analysis, organic petrology, and thermal modeling techniques indicate that the coal beds of the Tunas Formation could have a current potential as gas-prone source rocks. Despite that, the hydrocarbon generation capacity of coal levels is currently low due to the high percentage of residual (Type IV) kerogen. Further research could help clarify if the hydrocarbons potentially expelled by these source rocks have been lost due to migration or could be trapped somewhere in the basin.

The Wasps (Hymenoptera) from Lower Cretaceous Lebanese and Spanish Ambers

Hymenoptera is the fourth-most diverse insect order today, including wasps, bees, bumblebees, and ants. They show a wide panoply of modes of life, such as herbivory, predation, parasitoidism, pollination, and eusociality. This group also includes a great number of extinct species from both amber and compression outcrops. Hymenopterans probably originated in the Paleozoic, although their oldest record is from the Middle or Late Triassic, and their diversity expanded since the Cretaceous. Here, we present a review of the Hymenoptera in Lower Cretaceous ambers from Lebanon (Barremian) and Spain (Albian), which is pivotal for the study of hymenopteran evolution. Hymenoptera in Lebanese ambers are represented by 32 species in 22 genera within 15 families, while in Spanish ambers, they correspond to 49 species in 40 genera within 18 families. Most of these species belong to the ‘Parasitica’, and only a few species have been assigned to the Aculeata. The group ‘Symphyta’ is represented by one species in Spanish amber. The paleobiogeography and possible paleobiologies of the species in these ambers are reviewed. Furthermore, checklists for all Hymenoptera species in Lebanese and Spanish ambers are provided.

A seismic ambient noise data classification method based on waveform and frequency-wavenumber analysis: Application to reliable geological interpretation adjacent to Well Songke-2, Northeast China

Passive seismic interferometry techniques enable the retrieval of virtual shot gathers at receiver locations. However, it is difficult to distinguish body waves from surface waves in seismic ambient noise data, which leads to failed dispersion measurements, artificial deep reflections, and misleading geologic interpretations. We develop a new method that uses the waveforms and their corresponding f- k spectra to identify body waves and surface waves. Our technique functions as a data classification procedure before wavefield retrieval and subsequent imaging. A field data example is conducted to test the feasibility of this technique. The field data results demonstrate that our technique can reconstruct satisfactory high signal-to-noise-ratio wavefields for reliable imaging and interpretation purposes. The method can also serve as a validation tool for identifying surface wave-related artificial events in the obtained virtual source reflection image. The marker boundaries of the Songliao Basin in Northeast China are interpreted in the obtained profile and are in agreement with the well-logging data. In addition, two normal faults are detected, which correspond to the extensional rift environment during the early Cretaceous.

Flower Buds Confirmed in the Early Cretaceous of China.

The Yixian Formation (Lower Cretaceous) in China is famous worldwide for its fossils of early angiosperms, but there has been only one record of flower buds (Archaebuda lingyuanensis) hitherto, in which only the surface of the flower bud was documented while no internal details were known. Such a partial knowledge of flower buds hinders our understanding of the evolution of flowers, and this knowledge lacuna needs to be filled. Our new specimen was collected from an outcrop of the Yixian Formation (Barremian-Aptian, Lower Cretaceous) near Dawangzhangzi, Lingyuan, Liaoning, China. Our observations reveal a new fossil flower bud, Archaebuda cretaceae sp. nov., from the Lower Cretaceous of China. This new record of Archaebuda in the Yixian Formation not only confirms the truthful existence of the expected gynoecium (plus possible androecium) in a flower bud but also underscores the occurrence of typical flowers in the Early Cretaceous. This new information adds first-hand data to flower sexuality, pollination, and evolution.

Tectonic and sedimentary evolution of the Northern Cameroon Cretaceous rift basins: A study of the Babouri-Figuil and Mayo Oulo-Lere basins

The Babouri-Figuil and Mayo Oulo-Lere basins located in Northern Cameroon are small elongated sedimentary asymmetric half-grabens associated with the development of the West and Central African Rift System (WCARS). The evolution of these basins began during the Precambrian pre-rift period and continued through the Late Jurassic - Early Cretaceous periods, although details of their development remain unclear. The aim of this study is to understand the evolution and development of the border faults and their control on syn-rift geometry, accommodation space, and the resulting stratigraphic architecture. Using a combination of multiples surface and subsurface well logs data, we demonstrate the relationship and evolution of various stages of rifting and the associated sedimentary architecture. The basin is composed of an alluvial to lacustrine succession that developed during its tectonic evolution. A 3-stage tectonic model is proposed for the evolution of the basin that uses fault propagation analysis to describe the sedimentary architecture and evolution of basin geometry. The three stages of the model are the early rift, rift climax, and late rift; here, the early rifting phase is marked by the reactivation of faults in the Lower Cretaceous. The rift climax phase resulted in the interconnection of small segmented border faults leading to the high rate of activation of major border faults and to the development of the half graben structure of the basins. The late rift stage is marked by a decrease in border fault activity and accommodation. Sediment distribution and the facies architecture are controlled by tectonic subsidence created throughout the rifting phases. The stratigraphic signature of the Babouri-Figuil and Mayo Oulo-Lere basins are punctuated by the lacustrine water transgression-regression cycles, and controlled by the balance between the rate of sediment supply and tectonic accommodation. The progressive change between overfilled to starved sedimentary architecture is illustrated by this stratigraphic succession. Additional age assessment and sub-surface data in future work could help confirm the structures identified on the surface.

Flat‐footed Females and Missing Males: A New Genus and Species of Pleciofungivoridae (Diptera: Bibionomorpha) Represents the First Record of the Family from Mid‐Cretaceous Kachin Amber

AbstractA new genus and species, Cretopleciofungivora simpsoni gen. et sp. nov., from the extinct family Pleciofungivoridae (Diptera: Bibionomorpha), is discovered in mid‐Cretaceous Kachin amber. Previously, this family was known only from imprints in sedimentary rocks of the Jurassic and the Lower Cretaceous. Discovery of a representative of Pleciofungivoridae in Kachin amber confirms the presence of the family in the Upper Cretaceous. The new species has a unique structure of fore tarsus, with lobed and extended tarsal segments II to IV, a feature hitherto known only in a few species of extant Sciaroidea. Although not particularly rare, the new species is currently known only from female specimens. Possible reasons for this phenomenon, very unusual in Sciaroidea, are briefly discussed, including parthenogenesis as a potentially plausible hypothesis.

An exceptionally well-preserved Jurassic plateau-top to marginal escarpment in the Northern Apennines (Central Italy): sedimentological, palaeontological and palaeostructural features

Submarine palaeo-escarpment tracts at the basin margins commonly border isolated drowned carbonate platforms in the Jurassic rifted margins of the Western Tethys and bear fundamental structural and palaeogeographic significance. These tectonically generated escarpments, rooted in late Hettangian-early Sinemurian master faults, provide key information on the regional architecture of the rift, and on the nature and timespan of activity of the faults which define them. An isolated drowned carbonate platform (the Sabina Plateau) in the Northern Apennines of Central Italy exhibits a wealth of peculiar details on the Jurassic submarine topography. The deposits covering this escarpment host multiple unconformities related to a margin-failure episode, documented by breccias resting on a submarine-scar surface, perched with respect to the basin bottom and draped discontinuously by condensed ammonite-rich pelagites. Thin lenses of graded and laminated oolitic limestones in the condensed pelagic succession of the Sabina Plateau are interpreted as likely produced by the overbanking of turbidity currents, which were shed into the basin by a neighbouring productive carbonate platform. The final leveling of the submarine rift bathymetry occurred in the earliest Cretaceous, as documented by the onlap of the aggrading basinal succession against the palaeo-escarpment, and the burial of the plateau-top condensed succession. This complex onlap surface exhibits a distinctive overprint, such as diffuse silicification driven by the transit of silica-rich diagenetic fluids sourced by the radiolarian-rich basinal units.

Compaction Phases and Pore Collapse in Lower Cretaceous Chalk: Insight from Biot’s Coefficient

Compaction Phases and Pore Collapse in Lower Cretaceous Chalk: Insight from Biot’s Coefficient

Mеsozoic Tectonothermal Evolution of the Zagan Metamorphic Core Complex in Western Transbaikalia: 40Ar/39Ar and FTA Dating

Abstract A model of tectonothermal evolution of the Zagan metamorphic core complex (MCC) based on the new data from 40Ar/39Ar dating of amphibole, mica, and apatite fission-track dating is discussed. A relationship with the long-range impact of processes from the collision of the North China (Amurian–North China) block with the Siberian continent in the Mesozoic era is proposed. The Zagan MСС was formed in the Cretaceous period on the southern flank of a high mountain uplift of Western Transbaikalia, composed of late Paleozoic granitoids of the Angara–Vitim batholith. According to 40Ar/39Ar dating of amphiboles and micas from the mylonite zone, the active development time of the Zagan MCC corresponds to the early Cretaceous epoch (131, 114 Ma). The tectonic exposure of the core from about 15 km to the depths of about 10 km occurred at a rate of tectonic erosion of 0.4–0.3 mm/year as a result of post-collisional extension of the Mongol–Okhotsk orogen. Apatite fission-track dating shows that further exhumation and cooling of the rocks to about 3 km occurred in the lower-upper Cretaceous epoch (112, 87 Ma). The erosional denudation rate was about 0.3 mm/year.MCC- metamorphic core complexes, AFT- apatite fission-track

Chemical constraints and tectonic setting of the Ginebra ophiolite complex

The occurrence and types of ophiolites in the Central Cordillera of the Colombian Andes have not been identified in terms of their tectonic settings and geochemical features. Therefore, the study of the tectonic setting and subduction zones in the ophiolites’ magmatic evolution becomes a significant issue. The Ginebra Ophiolitic Complex (GOC) is located on the western flank of the Central Cordillera in the Valle del Cauca Department, southwest of Colombia, assigned to the Lower Cretaceous period, as indicated by the contact of the GOC with the Buga Batholith. The GOC is formed by three main lithologies: amphibolite, gabbro, and ultramafic rocks (pyroxenite and peridotite), according to Ossa (2007). The rocks in the Puente Piedra section, located in the northeast of Ginebra municipality, are part of the gabbroic cumulates within the ophiolitic sequence. This sequence comprises interspersed layers of gabbroic cumulates, gabbrodiorites, and diorites; interpreted as a result of crystal accumulation and fractional crystallization processes. The mafic rocks of the GOC are sub-alkaline and correspond to the low potassium (K2O wt% 0.03-0.06) tholeiitic series. Geochemically, they have SiO2 wt% ranging from 49 to 61 and an aluminum oxide saturation index of approximately ~0.4 and ~0.8, indicating a metaluminous type. The geochemistry of the studied rocks from Puente Piedra section indicates that the GOC formed through fractional crystallization and accumulation processes from a single magma source. Cluster analysis, used to compare the geochemistry of GOC rocks and the Amaime Complex basalts, suggests a similar magma source, possibly linked to multiple recharge events that underwent fractional crystallization, melt extraction, and accumulation processes. The geochemical parameters are indicative of a suprasubduction zone ophiolite, characterized by a low potassium tholeiitic series affinity, TiO2 values typically &lt;1.2 wt%, Th enrichment typical of subduction zones, high Pb content, and low values of Ti, Y, Yb, Ta, Nb, Zr, and Hf.

Geological characteristics of early cretaceous volcanic rocks and analysis of metallogenic potential of uranium mineralization in Moganshan basin, northern Zhejiang province, China

The Moganshan Volcanic Basin is located in the northeastern section of the Ganhang volcanic-tectonic-uranium polymetallic metallogenic belt. To explore the uranium mineralization potential of these volcanic rocks, petrographic, elemental geochemical, zircon U-Pb chronology, and Sr-Nd-Pb isotope analyses were performed on the volcanic rocks in the Moganshan Basin. The results showed that the volcanic rocks within the Moganshan Basin were formed at 130.8 ± 2.0 Ma; In addition, they are Si-rich (SiO2 content of 72.98%–77.32%), alkali-rich (Na2O+ K2O, with ALK values of =7.15–9.74), and potassium-rich (K2O/Na2O content of 1.41–4.34), with light rare earth elements (Rb, Th Nd, Zr, and Hf). Further more, the volcanic rocks within the Moganshan Basin are deficient in Ba, Ta, Nb, and Sr, with a negative europium anomaly (δEu of 0.10–0.17), high ISr (0.71028–0.71160), low εNd(t) values (−6.43–5.77), and other characteristics. The geological characteristics of the volcanic rocks in the Moganshan Basin are the same as those of the volcanic rocks in eastern China, and the formation age is Early Cretaceous. The formation environment is intra-land extensional and tensional. The rock-forming material primarily originates from the upper crust and has a higher average uranium content than that in the Ganhang volcanic belt. Additionally, it is speculated that the Moganshan Volcanic Basin has good potential for uranium mineralization.

Characteristics and long-runout mechanisms of the coarse-grained debris avalanche deposit in the ancient continental rift basin

Debris avalanche deposits are developed on slopes in various environments, including submarine volcanoes, continental volcanoes, continental slopes, and mountain ranges. In contrast, research is relatively scarce on the coarse-grained subaqueous debris avalanche deposits formed by the collapse of steep basin margins in continental small rift basins, which are controlled by tectonics. Through the interpretation of satellite imagery, field investigations, and the study of the morphological characteristics and internal structures of sediments, a massive debris avalanche event during the Early Cretaceous, Xiguayuan Formation of the Luanping Basin at the northern edge of the Yanshan tectonic belt on the North China Block, named the Wangying Debris Avalanche Deposit (WYDAD), has been identified and analyzed for its kinematics, dynamics, and long-runout mechanisms. The study reveals that based on sedimentology, internal structures, and basal characteristics, five different types of sedimentary morphologies can be identified from the source zone to the distal zone: convergent ridges and grooves (longitudinal expansion and lateral compression), transverse ridges and grooves (compression), longitudinal ridges and grooves (shearing and stretching), arcuate ridges and grooves (compression), and mixed sediments (radial extension). The grain size of coarse-grained debris avalanche deposits decreases with increasing transport distance and fragmentation due to jigsaw cracking, while matrix content increases. Additionally, the entrainment of fine-grained substrate and the mixing of lake waters during the transport of debris avalanches often evolve into secondary debris flows or high-density turbidity currents. Debris avalanches are likely primarily controlled by regional tectonic activity and volcanic action. Compared to subaerial debris avalanche deposits, the subaqueous WYDAD exhibits characteristics such as low fragmentation, smooth underwater terrain due to water resistance and buoyancy, and higher fluidity. The mechanism for the long-distance, high-speed transport of the WYDAD is explained by “hydroplaning” and high pore pressure generated by non-draining shear. This study provides insights into the transport processes of coarse-grained subaqueous debris avalanche deposits in continental rift basins. It verifies whether such sediments can serve as a primary sedimentary system for CCUS or potential resource storage.

A new abelisaurid dinosaur from the end Cretaceous of Patagonia and evolutionary rates among the Ceratosauria.

Gondwanan dinosaur faunae during the 20 Myr preceding the Cretaceous-Palaeogene (K/Pg) extinction included several lineages that were absent or poorly represented in Laurasian landmasses. Among these, the South American fossil record contains diverse abelisaurids, arguably the most successful groups of carnivorous dinosaurs from Gondwana in the Cretaceous, reaching their highest diversity towards the end of this period. Here we describe Koleken inakayali gen. et sp. n., a new abelisaurid from the La Colonia Formation (Maastrichtian, Upper Cretaceous) of Patagonia. Koleken inakayali is known from several skull bones, an almost complete dorsal series, complete sacrum, several caudal vertebrae, pelvic girdle and almost complete hind limbs. The new abelisaurid shows a unique set of features in the skull and several anatomical differences from Carnotaurus sastrei (the only other abelisaurid known from the La Colonia Formation). Koleken inakayali is retrieved as a brachyrostran abelisaurid, clustered with other South American abelisaurids from the latest Cretaceous (Campanian-Maastrichtian), such as Aucasaurus, Niebla and Carnotaurus. Leveraging our phylogeny estimates, we explore rates of morphological evolution across ceratosaurian lineages, finding them to be particularly high for elaphrosaurine noasaurids and around the base of Abelisauridae, before the Early Cretaceous radiation of the latter clade. The Noasauridae and their sister clade show contrasting patterns of morphological evolution, with noasaurids undergoing an early phase of accelerated evolution of the axial and hind limb skeleton in the Jurassic, and the abelisaurids exhibiting sustained high rates of cranial evolution during the Early Cretaceous. These results provide much needed context for the evolutionary dynamics of ceratosaurian theropods, contributing to broader understanding of macroevolutionary patterns across dinosaurs.

Two periods of magmatism in the Weishancheng ore concentration area, Henan Province: Evidences from zircon U‐Pb chronology, Hf isotopes and petrogeochemistry

The Weishancheng area of Tongbai County, Henan Province, is an important Au‐Ag polymetallic ore concentration area in China, characterized by a widespread distribution of plutons and frequent magmatic activities. To investigate the genetic relationship between magmatism and the mineralization of gold and silver polymetallic deposits in the area, this study focuses on the porphyritic monzogranite of the Liangwan pluton and the biotite granite of the Taoyuan pluton in detail. The zircon U‐Pb age of the Liangwan pluton is 128.5 ± 0.7 Ma, placing its intrusion age in the Early Cretaceous. Similarly, the zircon U‐Pb age of the Taoyuan pluton is 431.3 ± 2.7 Ma, indicating an intrusion age in the Early Silurian. Petrogeochemical analysis reveals that both the Liangwan and Taoyuan plutons exhibit high SiO2, Na2O and Al2O3 contents, along with low MgO, Fe2O3 and CaO contents, indicating a (high‐K) calc‐alkaline series, and have the properties of peraluminous I‐type granite. The total rare earth elements (REE) concentrations are low, with noticeable fractionation between light and heavy REE, and a negative Eu anomaly. High‐field‐strength elements (such as Nb, Ta, P, Ti) are depleted, while the large‐ion lithophile elements (such as Rb, K, Pb) are enriched. The εHf(t) values of the Liangwan and Taoyuan plutons range from −16.1 to −18.8 and from 11.0 to 14.6, respectively. The mean values of Hf two‐stage model ages (TDM2) are 603 Ma and 2230 Ma, respectively. These results suggest that the Liangwan pluton may have formed through partial melting of ancient crustal materials in the Palaeoproterozoic, during extensional tectonic events following the subduction of Izanagi Plate. It appears closely linked to Au‐Ag mineralization in the ore concentration area. The Taoyuan pluton likely originated from the depleted mantle and experienced some degree of crustal contamination. However, it is unrelated to regional mineralization.

Cretaceous palaeoceanographic events of the northern South Atlantic: an overview

Abstract The break-up of Gondwana in the latest Jurassic and earliest Cretaceous and the subsequent opening and evolution of the South Atlantic Ocean as a new widening seaway linking northern and southern high latitudes, was the single most significant palaeoceanographic event during the Cretaceous with global consequences for the climate and the biotic evolution, both on land and at sea. Its main evolutionary stages are now becoming well known but, despite that, their global impact has been widely underestimated. Aiming to shed light on some of these unanswered questions, this work presents an overview of research carried out during the past decades in the Sergipe Basin in northeastern Brazil, integrating foraminiferal and ammonite biostratigraphic data, coupled with an assessment of their biogeographic patterns. Three main topics are discussed, and the key findings presented and set against their possible global impact: the opening of the Equatorial Atlantic Gateway in the late early to mid Aptian ( c. 118–119 Ma); the mid-Cretaceous dysoxic–anoxic events recorded in the northern South Atlantic (maxima in the late Aptian–earliest Albian, early Cenomanian and at the Cenomanian–Turonian boundary); and the timing of the North Atlantic–South Atlantic oceanic connection in the late Coniacian to early Santonian ( c. 85–87 Ma).