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Oolitic ironstones in Lower (Toarcian) and Middle (Bajocian) Jurassic strata of the Indus Basin, Pakistan, were deposited in the eastern part of Tethys and are similar to those from India. Both units are represented by shallow-marine iron ooidal-siliciclastic wacke-packstone carbonates with sedimentary structures including ripple marks, cross lamination and trace fossils. Both the Toarcian and Bajocian iron ooids are mainly composed of goethite, the Toarcian ones have a higher Fe content than those in the Bajocian but the older unit has fewer silicate grains and lower contents of Si, Al, K and Sr. Thin to thick carbonate laminae occur between the Fe-rich laminae in the Bajocian iron ooids. The iron ooids in the Toarcian unit are related to phases of relative sea-level fall and represent deposition in a nearshore lagoonal setting whereas the Bajocian unit was deposited in a relatively broad spectrum of environments. The Fe itself was sourced from weathering of ferruginous soils and higher contents of K, Na, Ti and Ti/Al indicate a continental source. The cortical growth of the iron ooids in the Toarcian unit mainly took place under oxic conditions whereas conditions were more oxic to suboxic and anoxic in the Bajocian unit. The occurrence of spastoliths indicates the former presence of berthierine and the alternation of Fe-rich and carbonate-rich laminae within the Bajocian iron ooids suggests frequent burial and reworking of ooids in the near subsurface sub-oxic to anoxic environment. The subsequent exposure to oxic conditions on the seafloor likely altered the berthierine to goethite, which is stable in oxidizing conditions. [ABSTRACT FROM AUTHOR]

This paper presents, for the Queensland portion of the Rhaetian – Early Cretaceous Surat Basin, the results of a taxonomic-descriptive study of 89 palynological samples collected from three boreholes that intersected the succession containing the Gubberamunda Sandstone and the succeeding Orallo Formation, as well as the upper Westbourne Formation and the lower Mooga Sandstone, which respectively underlie and overlie this succession. This upper Westbourne Formation – lower Mooga Sandstone interval represents the most complete Late Jurassic – Early Cretaceous sedimentary succession in Queensland. It was sampled from: GSQ DRD 26, GSQ Roma 2 and GSQ Dalby 1, respectively located in the western, central, and eastern parts of the basin. The samples yielded a diverse palynoflora in which 212 taxa were identified, embracing both in-situ and reworked (latest Carboniferous – Early Jurassic) spores and pollen, as well as palynomorphs of algal, fungal, acritarch and unknown affinities. Formally included in this work is the previously unpublished taxonomy of McKellar, largely from the immediately preceding part of the Surat Basin succession, as its taxonomic nomenclature is critical to the current compilation. Herewith proposed (from both the current work and that of McKellar) are 27 new species, two new genera, 22 new combinations, ten emendations, the elevation of one subgenus to generic status, and the renaming of one species. From a biostratigraphic perspective, palynofloras from the upper Westbourne Formation and the lower Gubberamunda Sandstone are assigned to the informally defined 'Retitriletes watherooensis association zone', and palynofloras from the upper Gubberamunda Sandstone, Orallo Formation and lower Mooga Sandstone, to the Ruffordiaspora australiensis Interval Zone. The upper Westbourne Formation – lower Mooga Sandstone interval was deposited in lacustrine, floodplain and backswamp facies, with a flora that remained relatively stable, there being no major floristic turnover; it consisted of diverse ferns, conifers, lycopods, bryophytes, seed ferns, and a variety of ginkgoes, cycads, and/or gnetales. Humid, warm-temperate conditions are indicated by the flora's climatic signature. [ABSTRACT FROM AUTHOR]

This is an exclusively systematic background study reviewing 85 Mesozoic (latest Jurassic and Cretaceous) cockroaches and praying mantises from northern palaeo-polar (i.e. deposited within polar circles) deposits in Yakutia, Taimyr, Khabarovsk, Magadan and Chukotka (Russia), revealing 15 new species, which are herein characterised using systematic two-way analysis. The taphonomic conditions within these 'Arctic' paleo- polar sites were strongly influenced by long periods of pre-depositional transport. [ABSTRACT FROM AUTHOR]

The results of studying the Jurassic microfauna of the eastern shore of Anabar Bay are presented. Bajocian-Oxfordian microbenthic communities were reconstructed, characterizing two stages of foraminiferal development. The bionomic zones of the Anabar-Lena Sea in the area of the studied section are recognized. [ABSTRACT FROM AUTHOR]

Carbonates formed by anaerobic oxidation of methane at localized seeps have been recognized in the rock record based on a list of criteria, including anomalous deposition within detrital facies, complex petrofabrics, seep‐endemic macrofauna and 13C‐depleted isotopic signatures. While much emphasis has been placed on the latter, it is only one of several tools used for identification. This study reports on two different and rare limestone units in the forearc deposits of the Jurassic Bedford Canyon Formation in the Santa Ana Mountains, California (USA). Isolated, metre‐scale limestone pods were found to host abundant endemic Anarhynchia dimerelloid brachiopods and display diverse petrofabrics, including multiple generations of cements. However, the δ13C values of the petrofabrics ranged from −14.5 to 4.52‰ Vienna PeeDee Belemnite. These values are only slightly 13C‐depleted relative to contemporaneous seawater, thus likely recording a stronger component of oceanic dissolved inorganic carbon than hydrocarbons. Additionally, although the petrofabrics are common for seeps (primary micrite, microbialite, pelsparite, intraclastic micrite; early isopachous and botryoidal cements and yellow calcite; late‐stage void‐filling spar), the isotopic values did not follow a predicted trend of increasing δ13C with paragenetic sequence. Pelsparite δ13C values ranged from −10.65 to −7.09‰ Vienna PeeDee Belemnite while coarse spar and vein cements ranged from −11.42 to −2.44‰ Vienna PeeDee Belemnite. Olistostromes composed of brecciated pelmicrite sourced from shallow fringing‐arc environments are typical of forearc settings. Olistostromes in the Bedford Canyon Formation contain much lower δ13C values than the more classically characterized seep deposits, ranging from −21.77 to −10.78‰ Vienna PeeDee Belemnite. While the original shallow‐water source may not have a been a confined seep, the low δ13C values require the incorporation of carbon sourced from the oxidation of localized hydrocarbons. Together, these findings recommend a reconsideration of the weight placed on δ13C values as the key criterion for distinguishing seeps in the rock record. [ABSTRACT FROM AUTHOR]

Hydrogen sulphide (H2S) concentrations across three adjacent gas condensate fields in Southwestern Gissar produced from fractured Middle-Upper Jurassic reef-carbonates with anhydrite-bearing beds have been analysed. Wellsite testing measurements followed by iodometric titration showed concentrations of H2S below 0.2 mole%. Statistical analyses and cross plots of H2S vs. depth, reservoir temperature, porosity, anhydrite content, well tests and water saturation did not reveal linear correlations. Uniform gas condensate compositions and constant souring levels through time rule out secondary bacterial or/and technogenic processes, while temperatures bellow 90–110°С are against thermochemical sources. Low H2S values could result from mineral-fluid interactions within the host rock. However, low abundance of H2S and carbon dioxide (CO2) (<0.2 and <1 mole%) is also typical for thermogenic gases. Sour gas could be sourced from the deeply subsided up to 8–10 km axes of the Afghan-Tajik petroleum system. H2S concentrations here are generally around 1–2%. Diminished H2S concentrations in the fields are explainable by long distance migration losses from the source area 50 km apart. TSR is unlikely to be important contributor from the downdip part due to replacement of lagoonal anhydrites by distal carbonates. Interpreted logs, calibrated against XRD in the fields reveal anhydrite drop basinward from 30–100% to 0%. [ABSTRACT FROM AUTHOR]

Obayied sub-basin provides one-third of the annual natural gas production in the Egyptian Western Desert. The origin of the Obayied hydrocarbons are however poorly constrained. In this study, the molecular biomarkers of the Obayied hydrocarbon blend were studied to infer on their origin and generation mechanism. The API values are in the range of (41.3°–53.7°) reflecting post-mature hydrocarbons. The molecular biomarkers suggest a generation of Obayied crude from clay-rich fluvio-deltaic source rocks. Age- and maturity-relevant biomarkers (e. g., Ts/Tm trisnorhopanes and methylphenanthrene indices) reflect a successive expulsion of the Obayied crudes from mature Jurassic rocks (>1%Ro). Biological markers correlate perfectly with those of the Jurassic Khatatba shale and coal extracts attesting. Additionally, the Obayied gases are wet, thermogenic and have been derived from a mature type III kerogen (1.3%Ro–2%Ro). The studied gases display compositional characteristics of mixed coal- and oil-type gases, and were therefore derived via primary cracking of the Khatatba coal as well as secondary cracking of the light liquid crudes. The present study clarifies the controls on the geochemical processes responsible for the accumulation of liquid and gas hydrocarbon mix in the deep as well as shallow inverted rift basins of the north Western Desert, Egypt. [ABSTRACT FROM AUTHOR]

The geochemical characteristics and origin of Lower Jurassic dolomites from the Sarki and Sehkaniyan formations in the Imbricated Zone of Northern Iraq were investigated through analysis of major, trace, and rare earth elements, as well as stable isotopes (carbon and oxygen). The consistent CaO and MgO contents, their positive correlation, and elevated Mg/Ca values suggest an early penecontemporaneous sedimentary origin for dolomitization. These dolomites exhibit low Fe, Mn, and Sr contents, along with moderately low Na levels. Furthermore, they display low total rare earth element (ΣREE) contents, indicating low formation temperatures and a lack of light rare earth element (LREE) enrichment, while relatively negative δ18O values dismiss the influence of hydrothermal fluids on dolomitization. The patterns of rare earth elements normalized to the Post-Archean Australian Shale (PAAS) standard reveal a depletion of LREE compared to heavy rare earth elements (HREE), along with distinct negative Ce and positive Eu anomalies in most dolomites. The δ13C and δ18O values of the dolomites exhibit lower values than the contemporaneous seawater of the Lower Jurassic, which suggest the role of organic matter degradation and influence of meteoric water, respectively. Based on the petrographic and geochemical characteristics, the dolomite of the Lower Jurassic formations was mainly formed in the near-surface penecontemporaneous stage with late diagenetic recrystallization especially for Sehkaniyan dolomite. [ABSTRACT FROM AUTHOR]

The taxonomic histories of Pterodactylus antiquus and other pterodactyloids from the Upper Jurassic plattenkalks of southern Germany are long and complex, reflecting centuries of intricate and often contentious research. Among the most debated issues in pterosaur taxonomy is the relationship between Pterodactylus antiquus and Diopecephalus (Pterodactylus) kochi. Three distinct interpretations of their relationship have been proposed: (1) P. antiquus and D. kochi are conspecific and part of an ontogenetic sequence; (2) P. antiquus and D. kochi are sister taxa; (3) P. antiquus and D. kochi are distinct taxa and are not each other's closest relatives. Through an analysis of key anatomical features, including skull morphology, dentition and autopodial anatomy, we demonstrate that P. antiquus and D. kochi are distinct taxa that do not share close affinities. Phylogenetic analysis recovered D. kochi as the most basal member of Pterodactyloidea, retaining autopodial features comparable with those of non-pterodactyloids. Set within a temporal framework, this analysis challenges traditional assumptions regarding the pattern and timing of pterodactyloid evolution in the Jurassic, hinting at a longer and more complex history than previously realized. [ABSTRACT FROM AUTHOR]

The Jurassic record of South American theropods is scarce, being represented by only seven nominal species. Four of these species (Eoabelisaurus mefi, Asfaltovenator vialidadi, Condorraptor currumili and Piatnitzkysaurus floresi) have been found in Toarcian-aged localities in the Cañadón Asfalto Formation (Chubut Province, Argentina) and, as a result, this unit has the highest known diversity of Jurassic theropods on the continent. A dentary with teeth in situ (MPEF-PV 6775) was found close to the base of this formation and differs from the other species from the unit with overlapping morphology. MPEF-PV 6775 resembles the dentary of the Late Jurassic North American theropod Ceratosaurus in being a robust bone, with a strong dorsal curvature in lateral view, and having relatively tall tooth crowns. MPEF-PV 6775 was scored in two matrices that have a broad taxonomic sample focused on Theropoda and the new specimen was recovered in large polytomies with other early neotheropods. A third analysis was conducted scoring MPEF-PV 6775 into a matrix focused in ceratosaurs because of its morphological similarities to Ceratosaurus. In this analysis, MPEF-PV 6775 was recovered as the sister taxon to Ceratosaurus, sharing with the later a ventral margin of the dentary that is strongly convex anteroposteriorly. These results suggest that MPEF-PV 6775 is a ceratosaurian and probably a ceratosaurid. Thus, our results indicate a higher taxonomic diversity of theropods and, in particular, ceratosaurs in the Cañadón Asfalto Formation. MPEF-PV 6775 seems to provide more evidence for the presence of ceratosaurids in the Jurassic of South America, together with isolated teeth described from the Late Jurassic of Uruguay and some analyses that recovered Eoabelisaurus and Berberosaurus within this clade. [ABSTRACT FROM AUTHOR]

Deep coalbed methane (CBM) resources are abundant in China, and in the last few years, the country's search for and extraction of CBM have intensified, progressively moving from shallow to deep strata and from high-rank coal to medium- and low-rank coal. On the other hand, little is known about the gas content features of deep coal reservoirs in the eastern Junggar Basin, especially with regard to the gas content and the factors that affect it. Based on data from CBM drilling, logging, and seismic surveys, this study focuses on the gas content of Baijiahai Uplift's primary Jurassic coal seams through experiments on the microscopic components of coal, industrial analysis, isothermal adsorption, low-temperature CO2, low-temperature N2, and high-pressure mercury injection. A systematic investigation of the controlling factors, including the depth, thickness, and quality of the coal seam and pore structure; tectonics; and lithology and thickness of the roof, was conducted. The results indicate that the Xishanyao Formation in the Baijiahai Uplift usually has a larger gas content than that in the Badaowan Formation, with the Xishanyao Formation showing that free gas and adsorbed gas coexist, while the Badaowan Formation primarily consists of adsorbed gas. The coal seams in the Baijiahai Uplift are generally deep and thick, and the coal samples from the Xishanyao and Badawan formations have a high vitrinite content, which contributes to their strong gas generation capacity. Additionally, low moisture and ash contents enhance the adsorption capacity of the coal seams, facilitating the storage of CBM. The pore-specific surface area of the coal samples is primarily provided by micropores, which is beneficial for CBM adsorption. Furthermore, a fault connecting the Carboniferous and Permian systems (C-P) developed in the northeastern part of the Baijiahai Uplift allows gas to migrate into the Xishanyao and Badaowan formations, resulting in a higher gas content in the coal seams. The roof lithology is predominantly mudstone with significant thickness, effectively reducing the dissipation of coalbed methane and promoting its accumulation. [ABSTRACT FROM AUTHOR]

Understanding the tectonic evolution of ancient orogens relies on reconstructing the primary architecture of suture zones that may be modified by post‐subduction events. Modifications in East Junggar, southern Altaids, have led to controversial interpretations about the Paleozoic tectonic evolution. To clarify these relationships, we report the Mesozoic thrust horizon in East Junggar that has displaced the Baishanbao Klippe, which contains siltstone, sandstone, conglomerate and biogeographical Tuva‐Mongolia Tuvaella fauna. This klippe is distinct from units in the footwall that contain Ordovician‐Early Devonian accretionary complexes with dismembered basalts, cherts and deep marine tuffaceous siltstones, Carboniferous volcanic rocks and granites, Middle‐Late Jurassic sediments, and Kazakhstan biogeographic Ordovician‐Late Devonian coral‐brachiopod‐ammonoid fauna. The thrust horizon and the aforementioned units are unconformably capped by Late Jurassic‐Early Cretaceous alluvial fan deposits; it constrains the thrust to a Mesozoic age. These two biogeographic domains were separated by the Paleo‐Asian Ocean until the Late Paleozoic, as evidenced by the 478 Ma Kujibai MOR‐type ophiolite that involved into subduction zone in the Carboniferous. This Mesozoic thrust transported the Baishanbao Klippe for over 100 km southwards from its root in the Altay‐Fuyun area and crossed a cryptic suture zone of the Paleo‐Asian Ocean as an allochthonous unit in East Junggar. It extensively disrupted the primary Paleozoic orogenic architecture of East Junggar that leads to misinterpretation of the regional tectonic evolution. A lesson from disruption of this Mesozoic thrusting is that care must be taken in studies of the architecture of paleo‐suture zones. Key Points: The Tuva‐Mongolia biogeographic block containing Tuvaella sp. is distinct from blocks of the Kazakhstan domain in East JunggarThe Tuvaella sp.‐bearing Baishanbao Klippe was thrust over rock units of the Kazakhstan domain during the Late Jurassic‐Early CretaceousThe paleo‐suture zone of the Paleo‐Asian Ocean was disrupted by Mesozoic thrusts to complicate the crustal architecture of southern Altaids [ABSTRACT FROM AUTHOR]

Abstract Pterosaurs were the first vertebrates to evolve active flight. The lack of many well-preserved pterosaur fossils limits our understanding of the functional anatomy and behavior of these flight pioneers, particularly from their early history (Triassic to Middle Jurassic). Here we describe in detail the osteology of an exceptionally preserved Middle Jurassic pterosaur, the holotype of Dearc sgiathanach from the Isle of Skye, Scotland. We identify new autapomorphies of the flight apparatus (humerus and sternum), which further support the distinctiveness of Dearc compared with other early-diverging pterosaurs and describe features, such as the vertebral morphology, shared with later-diverging pterosaurs that probably developed convergently to support a large body size or as a sign of modular evolution. We used extant phylogenetic bracketing to infer the principal cranial and antebrachial musculature, indicating that Dearc had large and anteriorly placed palatal musculature that compensated for weak temporal jaw adductors and wing musculature suggestive of flight style reliant on powerful adduction and protraction of the humerus. Comparisons with other pterosaurs revealed that non-pterodactyloids such as Dearc, despite their overall conservative bauplans, adapted various flight and feeding styles. The osteology and myology of Dearc are indicative of a large predator that flew and hunted above lagoons and nearshore environments of the Middle Jurassic.

Foreland basins are rich in oil and gas resources, with most being concentrated in the foredeep zone. However, as breakthroughs in oil and gas exploration in post-uplift basins have been made, these types of basins gradually become a research hotspot. The hinterland of the Junggar Basin is a post-uplift basin, and the Jurassic Sangonghe Formation is an important oil and gas-bearing layer in this area. However, there is still a significant debate about the types of sedimentary facies in this formation. With the progress of exploration and the continuous enrichment of geological data, the types and evolution of the sedimentary facies in the Sangonghe Formation have gradually become clearer. To clarify the sedimentary facies types, distribution, and the differences from the foredeep zone in the post-uplift basins of the foreland basin system, the study analyzed geological profiles, cores, well logging, seismic data, and analytical test results. It provided a detailed analysis of the sedimentary facies types, distribution characteristics, and controlling factors of the Sangonghe Formation. The sedimentary facies types of the Sangonghe Formation include braided river delta facies, sublacustrine fan facies, and lacustrine facies. The braided river delta facies are further subdivided into the plain and front subfacies, which are mainly distributed in the Shixi and Mobei areas. The sublacustrine fan facies are mainly distributed in the west sag of well 1 in the basin, characterized by Bouma sequences, with "A" and "B" segments being mostly common. The sediment source for these fans came from the braided river delta in the eastern part of the study area. During the sedimentary period of the Sangonghe Formation, there were three sources in the study area, instead of only two sources from the northwest and northeast as previously believed. Stable heavy mineral analysis showed that the W36 sublacustrine fan was affected by the northeastern sediment source, while the W46 sublacustrine fan was affected by the southeastern source. Sediments in the foredeep zone of the foreland basin were coarse, with simple sedimentary facies types and structural oil and gas reservoirs as the primary trap types. However, sediments in the post-uplift basin had finer grain sizes, with more varied sedimentary facies types, and were dominated by tectonic-lithologic and lithologic oil and gas reservoirs.

Although China has abundant lacustrine shale oil resources, their exploitation is challenging. Investigating the various occurrence states of shale oil in shale reservoirs provides value for the exploration and development of shale oil resources. With the shale in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation of the central Sichuan Basin (the Da2 submember) as the research object, the study reveals the occurrence modes of shale oil under different states in various medium pores, through the implementation of the multi-temperature pyrolysis experiment, the observation of pore development characteristics under the scanning electron microscope and the analysis of the pore size distribution before and after oil washing. In the Da2 submember, the shale oil is mainly in the free state (0.42 to 10.88 mg/g), followed by the adsorption state (0.30 to 1.95 mg/g), as revealed by thermal simulation recovery. The reservoir space of shale includes organic pores (pore size: 2 to 600 nm), pyrite intergranular pores (pore size: 10 to 700 nm), shell pores (pore size: 20 to 1 000 nm), quartz/feldspar intergranular pores (pore size: 4 to 500 nm) and clay mineral intergranular pores (pore size: 4 to 500 nm). After oil washing, the results of nitrogen adsorption and high pressure mercury injection demonstrated a significant increase in pores with sizes of 2 to 30 nm and 60 to 1 000 nm, where most of shale oil is stored. Meanwhile, it was demonstrated that the shale oil in the Da2 submember mainly occurs in organic matter and pyrite by establishing a heat map of the relationship between the occurrence state of shale oil and the medium in the rock. Lastly, by fitting the content of shale oil in different occurrence states with the oil volume obtained before and after oil washing, the pore size range for shale oil accumulation in the study area was determined. The free state of shale oil in the Da2 submember primarily accumulates in pores of organic matter and pyrite with pore size of 60 to 700 nm, and the adsorbed state of shale oil mainly accumulates in the organic matter pores with pore size of 2 to 6 nm. In conclusion, this study presents a thorough examination of the occurrence characteristics of shale oil in Da2 submember, and it will support shale oil exploitation efforts in the area.

To further reveal the development characteristics of Jurassic source rocks in the southwest depression of the Tarim Basin and their paleoenvironments, with the aim of guiding future shale oil exploration and development, the study integrated rock pyrolysis, maceral analysis, inorganic geochemistry, biomarker compounds, and carbon isotope analyzes.It explored the development characteristics and organic matter enrichment patterns of coal-bearing mudstones from the Lower Jurassic Kangsu Formation and mudstones and silty mudstones from the Middle Jurassic Yangye Formation in the Kekeya area of the southwest depression, Tarim Basin. The results showed that the total organic carbon (TOC) content in the source rocks of the Kangsu and Yangye formations was relatively higher, ranging from 1.7% to 63.5% (with an average of 24.4%), and 0.6% to 6.9% (with an average of 2.1%), respectively, indicating source rocks of good to excellent quality. Source rocks from both formations exhibited low maturity, being in the low-maturity to mature stage.In addition, carbon isotope analysis of kerogen, thin section observations, and biomarker compound analysis indicated that the parent material of the organic matter in the coal-bearing mudstones of the Kangsu Formation and the lower section of the Yangye Formation mainly derived from higher terrestrial plants, while the silty mudstones of the upper section of the Yangye Formation contained abundant planktonic algae. During the depositional period of the Kangsu Formation, the paleoclimate was warm and humid, and the water environment was freshwater, with suboxic and slightly oxidizing conditions. In the early depositional stages of the Yangye Formation, the paleoclimate was also hot and humid, and the depositional environment was similar to that of the Kangsu Formation, characterized by freshwater and suboxic conditions. With the gradual rise in lake level in the late depositional period of the Yangye Formation, the paleoenvironment transitioned to a brackish and suboxic environment. The hot and humid climate, coupled with increased salinity, was conducive to the reproduction of planktonic algae and other aquatic organisms, thereby affecting the organic matter supply in silty mudstones of the upper section of the Yangye Formation. Furthermore, the enhancement of water reducibility during this period was also beneficial for the preservation of organic matter. In summary, paleoclimate, paleosalinity, and depositional environment are important factors influencing the organic matter enrichment in the Jurassic lacustrine source rocks of the Kekeya area.

China's tight sandstone reservoirs possess immense hydrocarbon reserves with substantial development potential. Hydraulic fracturing in horizontal wells is a crucial enhancement method for developing these reservoirs. In tight sandstone reservoirs of the Jurassic Shaximiao Formation of the J gas field in the transitional zone between central and western Sichuan, differences in rock mechanical properties and geomechanical characteristics result in significant variations in fracturing effectiveness across wells despite similar fracturing processes. To enhance the effectiveness and specificity of fracturing, this study examined the impact of three geological factors—brittleness index, minimum horizontal principal stress, and differences between two horizontal principal stresses—on fracturing effectiveness. Based on the difference in horizontal principal stress, the geological conditions in the study area were classified into two categories, type Ⅰ and type Ⅱ, from favorable to less favorable. The influence of various engineering factors on fracturing effectiveness under these two types of geological conditions was analyzed, and optimal ranges for engineering parameters under these conditions were proposed. The Analytic Hierarchy Process (AHP) and Grey Relational Analysis (GRA) were employed to calculate the influence weight of each geological and engineering parameter on fracturing effectiveness, and then a quantitative evaluation model was established. Based on the correlation with fracturing effectiveness, the AHP-based model was selected as the optimal method to evaluate the fracturing effectiveness in the study area. It was also used to verify the rationality of the proposed ranges for engineering parameters outlined in the study and the applicability of the comprehensive evaluation model for fracturing effectiveness. This paper revealed significant differences in the suggested parameter ranges for horizontal well fracturing engineering under different geological conditions, with notably broader ranges for wells in more favorable conditions than those in less favorable ones. The AHP-based model was identified as the optimal geological and engineering comprehensive evaluation model for assessing the fracturing effectiveness in the study area.

The imbibition law of the Jurassic continental shale in Fuxing area is not clear， which brings great challenges to the production test after well shut-in. In addition， studies on the imbibition law and influencing factors of continental shale are insufficient. Therefore， the experiment on the imbibition law of the Jurassic continental shale in Fuxing area was conducted based on the low-field nuclear magnetic resonance （NMR）. First， the differences in physical properties of shale of Lianggaoshan Formation and Dongyuemiao Member in Ziliujing Formation were tested and analyzed. Then， the changes in permeability and porosity before and after the imbibition were set as the evaluation indexes， and the influences of lithology， fluid， fluid pressure， and clay content on the imbibition law of the continental shale were analyzed. Besides， the wettability of the continental shale was evaluated. The experimental results show that compared with that of Dongyuemiao Member， the average porosity of shale of Lianggaoshan Formation is smaller， and the average permeability is larger； the average brittle mineral content is higher， and the average clay mineral content is lower. During the imbibition process of the Jurassic continental shale in Fuxing area， micro-fractures are induced by clay hydration， which provides additional imbibition channels. However， the imbibition ability of limestone is weaker than that of shale， and there are no micro-fractures during the imbibition； in addition， the shell limestone interlayer in the reservoir may inhibit the imbibition and micro-fracture propagation in the shale. The oil phase will enhance the micro-fracture propagation after the shale induces micro-fractures in the aqueous phase， and the complicated oil-water phase imbibition may be beneficial to the permeability improvement in the shale reservoir. Compared with atmospheric imbibition， pressureed imbibition has a limited effect on inducing micro-fractures and improving permeability， and the imbibition rate is larger； the imbibition equilibrium is earlier， but the imbibition amount is smaller. The influence of confining pressure on imbibition should be considered during well shut-in. The micro-fractures induced by hydration in shale with high clay mineral content are more significant， and the effect of improving permeability is more obvious. The imbibition rate and imbibition amount of shale in the oil phase are smaller than those in the aqueous phase， and the wettability of shale is hydrophilic. The experiment reveals the imbibition law and the characteristics of micro-fractures induced by the hydration of the Jurassic continental shale in Fuxing area， which provides a theoretical basis for the well shut-in and production test of continental shale during flowback.

Abstract Switzerland is an ichthyosaur country: it has a rich record of marine reptile fossils, particularly the fish-shaped ichthyosaurs, and the according research. Here, we provide an overview over the 12 or more genera and at least 13 species plus numerous fragmentary remains of ichthyosaurs from the Triassic to the Cretaceous that have been discovered in twelve cantons thus far, of which four species are based on Swiss holotypes. This wealth of ichthyosaur species can be explained by their abundance in the Middle Triassic conservation deposits (Konservat Lagerstätte) of Monte San Giorgio, as well as occasional discoveries in strata of Middle Triassic to Early Cretaceous age. The moderate abundance of outcrops in reasonable conditions in combination with the long history of palaeontological research in Switzerland explains this good fossil record. In addition to this unique overview, we provide more data for further studies and update the knowledge of these taxa.

The Middle–Upper Jurassic strata in the eastern part of the Alborz, North of Iran (Dalichai Formation) were studied based on ammonite fauna to correlate with zonation of other West Tethyan areas (Sub-Mediterranean province). In this section, like other studied sections in North and northeast of Iran, the ammonite assemblages such as Parkinsoniidae, Morphoceratidae, Sphaeroceratidae, Macrocephalitidae and Reineckeiidae mainly show the characteristics of etyan groups. Abundant ammonite fauna in some levels has enabled an accurate chronostratigraphy. The presence of this ammonite fauna that is seen in the epicontinental seas, bordering the northern margins of the western Thetys, led to the identification of some zones in accordance with the standard of Sub-Mediterranean province zonation. The Garantiana and Parkinsoni Zones of the Late Bajocian, the Zigzag and Aurigerus Zones of the Early Bathonian, the Retrocostatum and Discus Zones of the Late Bathonian, the Bullatus and Gracilis Zones of the Early Callovian, the Anceps and Coronatum Zones of the Middle Callovian and the Athleta and Lamberti Zones of the Late Callovian have been recognised and characterised. These assemblages show a relation between these regions with the Sub-Mediterranean province during the Jurassic. Low percentage of Phylloceratidae in this section is an indicative of Sub-Mediterranean affinity. Based on the ammonite fauna, the Dalichai Formation is Late Bajocian-Late Oxfordian in age. [ABSTRACT FROM AUTHOR]

The Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic) is marked by widespread marine deoxygenation and deposition of organic carbon (OC)-rich strata. The genesis of the T-OAE is thought to be associated with environmental changes caused by the emission of 12C-enriched greenhouse gasses (CO2, CH4), manifested in a negative Toarcian carbon isotope excursion (nT-CIE). The nT-CIE is commonly used to stratigraphically define the T-OAE, and despite the complex interrelationship of the different environmental phenomena, both terms (nT-CIE and T-OAE) are commonly used interchangeable. We here demonstrate that occurrence of OC-rich strata is diachronous and not restricted to the nT-CIE, reflecting the interaction of global- and regional-scale processes. Thus, the interchangeable use of T-OAE and nT-CIE should be discarded. The nT-CIE, however, hosts the T-OAE climax, marked by the widest extent of OC-rich strata. Early Toarcian environmental changes, particularly sea level rise and rising temperatures, may have made marine areas more susceptible to develop oxygen deficient conditions, favoring OC-accumulation. [ABSTRACT FROM AUTHOR]

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Copyright of Petroleum Geology & Experiment is the property of Petroleum Geology & Experiment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Experiment is the property of Petroleum Geology & Experiment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Uranium Geology is the property of Uranium Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An assemblage of Middle Jurassic (Bajocian) hybodonts is described from the Hamira and Joyan members of Jaisalmer Formation, Rajasthan state, western India. Four hybodont species are recognised based on isolated teeth – Strophodus jaisalmerensis, S. magnus, ?S. indicus and Planohybodus aff. grossiconus. The new assemblage, recovered from near-shore marine strata, represents one of the oldest records of Jurassic hybodonts in the entire Gondwana. Paleobiogeograhic considerations suggest a pathway for the migration of the genus Strophodus from Europe to Jaisalmer and Kutch basins in western India during the initial phases of the formation of these basins. [ABSTRACT FROM AUTHOR]

The Pliensbachian (Lower Jurassic) age-based Lower Marly Limestone Formation of the Moulay Idriss Zerhoun area (Morocco) and the Ain Ouarka Formation of the Ksour Mountains (Algeria) have yielded rare crinoids. Although crinoids have previously been described from the Jurassic of Algeria, their Pliensbachian occurrence is being reported here for the first time. On the other hand, one isocrinid taxa [Terocrinus subsulcatus (Münster in Goldfuss)] was also recorded from the Pliensbachian strata of Morocco. Additionally, now, from both Morocco and Algeria, Seirocrinus subangularis (Miller), belonging to the family Pentacrinitidae, is documented. This is a cosmopolitan and pseudoplaktonic crinoid species that is well-known from Asia, Europe, and North America. The taxonomic evaluation of the genus Seirocrinus is provided. The present records from Algeria and Morocco are the first finds of Seirocrinus from the African continent. Ticinocrinus moroccoensis sp. nov. represented by a cup of a rare cyrtocrinid (Cyrtocrinida) is associated with S. subangularis from Morocco. Globally, this is the second record of the genus; the first Ticinocrinus being described from the Pliensbachian of Switzerland. Thus, the present records from Morocco and Algeria are also the oldest cyrtocrinids from the southern margin of the Tethys. [ABSTRACT FROM AUTHOR]

The Toarcian (upper Lower Jurassic) strata of the world-renowned Posidonia Shale of Central Europe have yielded diverse assemblages of marine vertebrates. Some of them, such as those of the Holzmaden area in southwestern Germany, are among the best-preserved specimens of Lower Jurassic vertebrate taxa. Here, we provide a reassessment of 'Plesiosaurus' bavaricus, a long-overlooked plesiosaur taxon from the Posidonia Shale of northern Bavaria (southern Germany), established based upon two isolated cervical centra and a caudal vertebra. The cervical material exhibits an intriguing character combination, providing evidence for the presence of a distinct plesiosaur taxon in the upper Lower Jurassic of the Posidonia Shale of Germany. Additionally, we report another isolated cervical vertebra, likewise from the Posidonia Shale of Bavaria, that shows striking similarities to the type cervicals of 'P'. bavaricus. Following our study of the Bavarian specimens, we hypothesise that, despite their substantial incompleteness, it seems likely that the material belonged to the same taxon, either species or a group of species, distinct from other plesiosaurs known from the Posidonia Shale. [ABSTRACT FROM AUTHOR]

Virtual palaeontology is a growing field, leading palaeontologists to better understand the microanatomy of many extinct species. The application of techniques such as CT and μCT-scanning allows the researchers to study micro-anatomical features in a non-invasive way and make inferences on the palaeobiology of animals. Dinosaurs have been extensively studied using these techniques, with particular focus on the microanatomy of the cranium, whereas relatively little is known of other cranial elements, such as the lower jaw. Here, we aim to fill this gap, describing the microanatomy of the specimen ML 768, an isolated dentary belonging to a dryosaurid iguanodontian dinosaur from the Upper Jurassic of Lourinhã Fm. The dentary ML 768 was subjected to μCT-scanning, and subsequently the data were segmented in Avizo and rendered in Blender. We identified functional and replacement teeth, recognising remnants of old replacement cycles. Furthermore, we mapped a rich neurovascular network present in the dentary and compared it with reference literature. We found that the high vascularisation is shared with other cerapodan dinosaurs with high tooth replacement rates, although homoeostasis may have also played a role in the development of this condition. Further evidence is needed to appreciate the macroevolutionary significance of these findings. [ABSTRACT FROM AUTHOR]

In order to study the hydrocarbon generation (HCGE) characteristics of coal‐bearing basins, the coal‐measure source rocks of the Middle Jurassic–Lower Jurassic (MLJ) of the piedmont thrust belt in the southern margin of the Junggar Basin in Northwest China are taken as research objects. More than 60 MLJ samples were collected from outcrops and wells. Total organic carbon (TOC), rock pyrolysis (Rock–Eval), organic petrological, vitrinite reflectance (%Ro), and hydrous pyrolysis were performed to analyze the relevant samples. The pyrolysis gases and liquid products were measured, and then the chemical composition, as well as carbon isotopes of the gases, were analyzed. The results indicate that the MLJ source rocks have the capacity for large‐scale gas generation. In addition, for coal‐measure source rocks, the heavier the carbon isotope of kerogen (δ13Ckerogen), the lower the liquid hydrocarbon and hydrocarbon gas yield, and the easier it is to produce non‐hydrocarbon gas. It is worth noting that when the δ13Ckerogen in organic matter (OM) is relatively heavier, the fractionation of its products may become weaker in the evolutionary process. The vital contribution of the MLJ source rock to natural gas resources in the study area was further confirmed by comparing it with the Jurassic source gas. [ABSTRACT FROM AUTHOR]

Data from over 80 boreholes have been used together with the surface geology to interpret the subsurface structure and stratigraphy of the Corallian to Gault (Upper Jurassic to Lower Cretaceous) sediments in the Vale of the White Horse, between Faringdon and Wantage in West Oxfordshire. The gentle regional dip to the SSE of the sediments in this area is interrupted by two major features. The first is the Faringdon Fault, first defined at outcrop just east of Faringdon. This has been traced SE from the outcrop extent for at least 8 km in the subsurface towards Wantage. It has an estimated maximum downthrow to the SW of ca 40 m. Contrary to previous interpretations, this fault was probably active during Kimmeridge Clay deposition. The second feature is the Faringdon Trough, an erosional palaeovalley filled with at least 50 m of marine Lower Greensand sediments. The Trough trends SSE from Faringdon and cuts deeply through the Kimmeridge Clay to reach the underlying Corallian. A subtle structural feature, here named the Baulking Fault, has a throw of < 10 m and its movement was probably pre-Cretaceous, but it seems to have influenced the path and geometry of the Faringdon Trough, dividing it into two segments. Contrary to previous interpretations, subsurface mapping suggests that the main Trough has a broad U-shape in cross-section with a planar base where it rests on resistive Corallian limestone. Along its margins depositional dips of up to 9° have been widely recorded in the Lower Greensand sediments. [ABSTRACT FROM AUTHOR]

Stromatolites in the essentially non-marine Purbeck Formation (Tithonian, Upper Jurassic) west of Aylesbury (Buckinghamshire, UK) cap an erosion surface truncating lacustrine–palustrine carbonates, previously documented from an exposure close to the site of the former Bugle Pit, Hartwell. The stromatolite occurrences in this area follow a regional northwest–southeast structural grain, evidenced by local normal faults, some demonstrably active during Late Jurassic–Early Cretaceous time. Observations from associated lithofacies and biota suggest a littoral lacustrine setting for the stromatolite 'belt'. We hypothesise that the present-day stromatolite distribution reflects a fault-controlled palaeo-shoreline, and that growth of the stromatolites was linked to lacustrine transgression driven by syn-sedimentary movement on these faults. Littoral sand associated with the stromatolites was possibly reworked from older marine sediments undergoing erosion on a nearby fault footwall, or distally, on the western margin of the Anglo-Brabant Massif. [ABSTRACT FROM AUTHOR]

Background: The superorder Forcipulatacea is a major clade of sea stars with approximately 400 extant species across three orders (Forcipulatida, Brisingida, Zorocallida). Over the past century, the systematics of Forcipulatacea have undergone multiple revisions by various authors, with some considering numerous families such as Asteriidae, Zoroasteridae, Pedicellasteridae, Stichasteridae, Heliasteridae, Labidiasteridae, and Neomorphasteridae, while others recognized only two families (i.e., Asteriidae and Zoroasteridae). Recent molecular analyses have shown the artificial nature of some of these groupings. Notably, four well-supported clades (Zorocallida, Brisingida, Stichasteridae, and Asteriidae) emerged from a synthesis of morphological and molecular evidence. The majority of extinct forcipulatacean species have been placed in modern families. However, many of these fossil species are in need of revision, especially those species placed within the Asteriidae, the largest of all forcipulatacean families. Methods: In light of recent advancements in forcipulatacean systematics, we comprehensively reassess six well-preserved Jurassic forcipulatacean taxa, including the earliest crown-group members from the Hettangian (∼201.4 Ma), and also describe two new Jurassic genera, Forbesasterias gen. nov. and Marbleaster gen. nov. We assembled the largest and most comprehensive phylogenetic matrix for this group, sampling 42 fossil and extant forcipulatacean species for 120 morphological characters. To infer phylogenetic relationships and construct an evolutionary timeline for the diversification of major clades, we conducted a Bayesian tip-dating analysis incorporating the fossilized birth-death process. A total of 13 fossil species were sampled in our analysis, including six taxonomically revaluated herein, two recently reappraised species from the Jurassic, and five additional species from the Cretaceous and Miocene. Results: Contrary to prior assumptions, our results indicate that none of the Jurassic taxa investigated belong to Asteriidae or any other modern families, and instead represent stem-forcipulatids. Furthermore, our phylogenetic results suggest that Asteriidae likely originated during the late Cretaceous. Our findings highlight a greater early diversity within the Forcipulatacea than previously presumed, challenging existing perceptions of the evolutionary history of this significant clade of marine invertebrates. [ABSTRACT FROM AUTHOR]

A causal mechanism for the Volgian Isotopic Carbon Excursion (VOICE) remains enigmatic. Elemental geochemical profiles of the Deer Bay Formation, Sverdrup Basin, Arctic Canada that record the VOICE and contemporaneous strata are herein examined to provide insight into depositional environments during Late Jurassic‐Early Cretaceous time. Silver (Ag) and Cadmium (Cd) are enriched across the VOICE at localities on Axel Heiberg Island, and in Tithonian (∼Volgian) strata of Ellef Ringnes Island. Other redox‐sensitive trace elements do not exhibit spatially or temporally consistent patterns and indicate oxic conditions. A lack of relationship across the VOICE between Ag and the quality, quantity, and isotopic composition of organic matter suggests that the negative isotope excursion and interval of Ag enrichment are not merely functions of changes in organic matter source or amount, while a lack of spatially consistent change in geochemical indices of weathering similarly excludes climate change and/or sediment provenance as a driver. Therefore, in a ventilated setting and without marked changes in organic matter content, Ag enrichment may be due to hydrothermal activity. Contemporaneous Ag enrichment in strata from Svalbard suggests that a source of hot fluid sufficient to produce Ag‐rich seawater may have been related to rifting in the adjacent proto‐Amerasia Basin. Hydrothermal activity may also have been a widespread source of isotopically depleted carbon. This work develops new geochemical fingerprints that may be used to trace the spatial extent of hydrothermal events that do not leave an extinction pattern but may nonetheless have a far‐reaching influence on biogeochemical systems. Plain Language Summary: Silver (Ag) is enriched in marine sedimentary strata of Tithonian age, and in particular, across the Volgian Isotopic Carbon Excursion in Arctic Canada. However, other redox‐sensitive trace elements do not exhibit spatially or temporally consistent patterns, and collectively suggest oxygenated conditions near the seafloor during this time. Contemporaneous Ag enrichment in strata from Svalbard suggests that a source of hot fluid sufficient to produce Ag‐rich seawater may have been related to rifting in the adjacent proto‐Amerasia Basin. Hydrothermal activity may also have been a widespread source of isotopically depleted carbon. This work develops new geochemical fingerprints that may be used to trace the spatial extent of hydrothermal events that do not leave an extinction pattern but may nonetheless have a far‐reaching influence on biogeochemical systems. Key Points: Silver is enriched across the Volgian Isotopic Carbon Excursion (VOICE) in the Canadian ArcticOther redox‐sensitive trace elements do not exhibit spatially or temporally consistent patterns and indicate oxic conditionsRifting in the proto‐Amerasia Basin may have resulted in hydrothermal activity that caused the silver enrichment [ABSTRACT FROM AUTHOR]

Bolivia has an outstanding tetrapod ichnological record from the uppermost Cretaceous deposits plus a new Triassic locality recently reported. Here, we report a new ichnosite, the first for the Jurassic to earliest Cretaceous in the Castellón Formation (Tarija, Bolivia) bearing about 350 dinosaur tracks. With the exception of few tridactyl tracks, all exhibit sauropod characteristics. The exposed set consists of three mediumgauge, subparallel large quadrupedal trackways, with one trackway oriented in opposite direction to the other two. The best preserved trackway shows large pedes of about 95 cm and 75 cm in length and width, respectively. The trackmaker was about 3.80 m in height at the hip and walked at a speed under 5 km/h. Available evidence suggests that the producer of the more detailed trackway may be a member of non-Neosauropoda Eusauropoda, even if a titanosauriform producer cannot be discarded. Dozens of small-sized sauropod tracks, less than 15 cm in pes diameter, appear associated with two of the trackways. The distribution of these trackways provides elements to test gregariousness among trackmakers if a possible synchronism is accepted. Wanderings recognisable on the sediment surface suggest that they may collectively represent an ichnological example of herd behaviour. [ABSTRACT FROM AUTHOR]

New Mesozoic (Kimmeridgian to Albian) corals from northern Mexico (Mexican states Coahuila, Durango and Sonora), that were established by Imlay and Wells between 1940 and 1946, are revised on the basis of the type material kept at the Museum of Paleontology of the University of Michigan in Ann Arbor (Mich., USA). From the six new species, only one may remain in use, and the other five species are considered to be synonyms of older taxa. [ABSTRACT FROM AUTHOR]

Our revision of the type material of Liodesmus led to significant adjustments in our understanding of the taxon when the original type specimen of Pholidophorus gracilis, which was later determined as the type species of the genus Liodesmus, was recently found in the collection in Berlin. It had been confused with a specimen that was described as the type specimen of the species Liodesmus gracilis in the collection in Munich. Moreover, the Munich specimen was mistakenly considered by all authors who have studied Liodesmus as a type specimen for the genus Liodesmus. However, the original holotype of Pholidophorus gracilis and this Munich specimen of Liodesmus gracilis belong to two different families. Caturus brevicostatus, whose holotype was recently found in Berlin as well, is described in detail here for the first time. Liodesmus sprattiformis is now described under the new genus Nasrinsotoudehichthys outside Caturidae but within the Caturoidea. Since all specimens that have been described so far under Liodesmus either belong to other, previously described genera, belong to new genera clearly outside the description of the genus Liodesmus, or are nomina dubia (including the type species Pholidophorus gracilis), the genus Liodesmus and the Liodesmidae are nomina dubia as well. [ABSTRACT FROM AUTHOR]

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Switzerland is an ichthyosaur country: it has a rich record of marine reptile fossils, particularly the fish-shaped ichthyosaurs, and the according research. Here, we provide an overview over the 12 or more genera and at least 13 species plus numerous fragmentary remains of ichthyosaurs from the Triassic to the Cretaceous that have been discovered in twelve cantons thus far, of which four species are based on Swiss holotypes. This wealth of ichthyosaur species can be explained by their abundance in the Middle Triassic conservation deposits (Konservat Lagerstätte) of Monte San Giorgio, as well as occasional discoveries in strata of Middle Triassic to Early Cretaceous age. The moderate abundance of outcrops in reasonable conditions in combination with the long history of palaeontological research in Switzerland explains this good fossil record. In addition to this unique overview, we provide more data for further studies and update the knowledge of these taxa. [ABSTRACT FROM AUTHOR]

Establishing the temporal sequence of the Middle-Late Jurassic Yanliao Biota is essential as it anchors the timing of many key evolutionary innovations in vertebrates. Lack of sufficiently reliable high-precision ages of fossil-bearing horizons hinders our ability to reconstruct the tempo and mode of vertebrate evolution. Here, we frame a temporal sequence of Yanliao Biota with precise age constraints for iconic vertebrates, proposing that the major vertebrate-bearing strata span from 164 Ma to 157 Ma in age. The increasing ecological diversity of mammaliaforms is well illustrated by the Middle-Late Jurassic Yanliao Biota and Early Cretaceous Jehol Biota. Incorporation of the updated temporal frameworks in Bayesian tip-dated mammaliaform phylogeny reveals that Triassic haramiyidans are separate from Jurassic taxa and unrelated to crown Mammalia. Tip-dated phylogeny supports a long-fuse model for mammal evolution, featured by a Late Triassic root and Middle-Late Jurassic interordinal diversification of crown Mammalia, showing consistency with molecular-based timetrees in divergence timing.

Yinlong downsi, the earliest known ceratopsian, is represented by dozens of specimens of different sizes collected from the Upper Jurassic of the Junggar Basin, northwestern China. Here, we present the first comprehensive study on the bone histology of Yinlong downsi based on ten specimens varying in size. Four ontogenetic stages are recognized: early juvenile, late juvenile, subadult, and adult. The reconstructed growth curve suggests that Yinlong may reach sexual maturity at 6 years old, which is earlier than that of the well-studied early-diverging ceratopsian Psittacosaurus (9 years old) but later than ceratopsids (about 3 to 5 years old). This may indicate that sexual maturity begins earlier during the evolution of ceratopsians, and that the giant size of ceratopsids is acquired by accelerating growth rates. The cortex of the tibia mainly consists of fibrolamellar bone tissues, but parallel-fibered bone and lines of arrested growth (LAGs) are very common throughout ontogeny, suggesting a moderate growth rate. Quantitative analysis indicates that Yinlong has a maximum growth rate similar to those of other small-sized dinosaurs such as Psittacosaurus, Dysalotosaurus, and Troodon, and their maximum growth rates are higher than those of extant squamates and crocodiles but lower than those of extant mammals and large dinosaurs. This suggests that body size plays a more important role in growth rate than other factors such as phylogenetic position and/or diet among non-avian dinosaurs.

As the first group of tetrapods to achieve powered flight, pterosaurs first appeared in the Late Triassic. They proliferated globally, and by the Late Jurassic through the Cretaceous, the majority of these taxa belonged to the clade Monofenestrata (which includes the well-known Pterodactyloidea as its major subclade), typified by their single undivided fenestra anterior to the orbit. Here, a new taxon Melkamter pateko gen. et sp. nov., represented by the specimen MPEF-PV 11530 (comprising a partial cranium and associated postcranial elements), is reported from the latest Early Jurassic (Toarcian) locality of Queso Rallado (Cañadón Asfalto Formation) and referred to the clade Monofenestrata, increasing our previously known taxonomic and geographic representations, and temporal range for this clade. This occurrence marks the oldest record of Monofenestrata globally and helps to shed critical light on the evolutionary processes undergone during the ‘non-pterodactyloid’-to-pterodactyloid transition within the Pterosauria. In addition, another single isolated tooth from the same locality shows ctenochasmatid affinities. These finds further elucidate the still-poor Gondwanan Jurassic pterosaur fossil record, underscoring that most of our current ideas about the timing and modes of pterosaur evolution during that period are largely based on (and biased by) the pterosaur fossil record of the Northern Hemisphere.