The first aeshnoid dragonfly (Odonata: Anisoptera: Telephlebiidae) from mid-Cretaceous Burmese amber     

《Cretaceous Research》2017

A new true dragonfly, Cretaeshna lini gen. et sp. nov., is described based on a forewing from mid-Cretaceous Burmese amber. Cretaeshna is probably a member of Telephlebiidae: Telephlebiinae, but differs from the latter in having a weakly-defined IR1 and a short pterostigma. Cretaeshna lini is the first aeshnid dragonfly to be found as an amber inclusion and the third Cretaceous true dragonfly recorded in amber. Our find augments the diversity of Mesozoic true dragonflies, and enhances our understanding of the palaeogeographic distribution of aeshnid dragonflies.  相似文献   

Micropaleontological evidence for redox changes in the OAE3 interval of the US Western Interior: Global vs. local processes     

《Cretaceous Research》2017

The Coniacian-Santonian interval has been proposed as the youngest of the Cretaceous ocean anoxic events (OAE3), but this designation has long been debated. OAE3 is associated with a long-lasting (∼3 myr) succession of black shales from the central and South Atlantic, Caribbean region, and the North American Western Interior; in the Western Interior it is characterized by an abrupt increase in total organic carbon (TOC) and corresponding trace metal indicators for anoxia. However, the modern concept of OAEs is predicated on detection of global carbon cycle perturbations as recorded by substantial carbon isotope excursions (CIE), and the protracted Coniacian-Santonian black shale interval does not have a large CIE. A more conservative definition of OAE3 might limit the event to the modest positive carbon isotope excursion restricted to the upper Coniacian Scaphites depressus Ammonite Zone. Trace metal proxies suggest that oxygen levels abruptly declined prior to the onset of this CIE in the Western Interior Sea (WIS), but it is unknown whether regional anoxic conditions were confined to sediments/pore waters, or how anoxia may have affected the biota. In an effort to characterize the oxygenation history of the WIS and to better understand the nature of the hypothesized OAE3, we present micropaleontological evidence of declining oxygen in bottom waters prior to the event using benthic foraminifera, which are sensitive to dissolved oxygen. Changes in benthic foraminiferal abundances suggest a decline in oxygen at least 1-myr prior to the CIE (including a nadir immediately below the start of the excursion), improving bottom water oxygen during the CIE, and re-establishment of persistent anoxia following the isotope excursion. Anoxia endured for nearly 3 myr in the central seaway, showing some signs of recovery toward the top of the Niobrara Formation. Our findings suggest that declining oxygen concentrations in the seaway eventually reached a tipping point, after which dissolved oxygen quickly dropped to zero.The late Coniacian CIE is an exception to the trend of declining oxygen in the WIS, and part of a larger pattern in the oxygenation history of the Niobrara Formation which suggests that it does not adhere to standard black shale models. Transgressive periods, including the Fort Hays Limestone and the lower limestone unit of the Smoky Hill Shale (which corresponds to the CIE) are relatively oxic, while periods of highstand (i.e., most of the Smoky Hill) correspond to deteriorating oxygen conditions. This contrasts with the standard black shale model for sea level and oxygen, where transgressions typically correlate with maximum TOC enrichment, interpreted to result from both sediment condensation and oxygen deficiency. The association of global carbon burial/anoxia (as indicated by carbon isotopes) with a regional increase in oxygen and decrease in organic matter preservation is reminiscent of the Cenomanian-Turonian Greenhorn Limestone, which contains OAE2. In both cases, the facies are not typical black shales, but instead have appreciable carbonate content. Western Interior redox trends support the rejection of the original concept of a protracted Coniacian-Santonian OAE3 because it is not a distinct “event.” Increasing local oxygen during the late Coniacian CIE also argues against a narrower OAE designation for this event, because the excursion can't be tied to anoxia here or anywhere else it has been described. Nevertheless, the Late Coniacian Event (as we prefer to call this CIE) still represents an important perturbation of the global carbon cycle. This is emblematic of the shift away from widespread, discrete anoxic events during the ongoing paleoceanographic reorganization of the Late Cretaceous, even as large carbon cycle perturbations continued.  相似文献   

First occurrence of tyrannosaurid theropods from the Corral de Enmedio Formation (Upper Cretaceous) Sonora,México     

《Cretaceous Research》2017

The Cabullona Basin in the state of Sonora, Mexico is becoming recognized due to its diversity of southern Laramidian continental vertebrates, especially dinosaurs. In this study we describe and analyze three theropod teeth (ERNO specimens) that were found isolated and surface collected in the Corral de Enmedio Formation (Cabullona Group, Upper Cretaceous). The three specimens possess similar morphological characteristics that match the ones present in Late Cretaceous Laramidian tyrannosaurids, so they were referred to the Tyrannosauridae, probably belonging to a new unknown taxon. The implementation of statistical and cladistic analyses corroborated their taxonomical assignment. ERNO specimens correspond to the first record of tyrannosaurid dinosaurs in the basal Corral de Enmedio Formation, extending the stratigraphic distribution of these dinosaurs in the Cabullona Basin. Although tyrannosaurids have been previously described in the Cabullona Basin, the ERNO specimens of the Corral de Enmedio Formation seem to be different, because they possess more labiolingually compressed teeth. This new evidence could indicate a higher taxonomic diversity of the tyrannosaurid theropods that were present in the Cabullona Basin, adding more information to the Tyrannosauridae diversification on one of the most southern Laramidian regions during the Late Cretaceous.  相似文献   

New records of coleoid cephalopod jaws from the Upper Cretaceous of Hokkaido,Japan, and their paleobiogeographic and evolutionary implications     

《Cretaceous Research》2017

Seven coleoid jaws recovered from Santonian to lower Campanian (Upper Cretaceous) strata in Hokkaido, Japan were taxonomically studied. Based on the comparison with the jaws of modern and fossil coleoids, six of the seven jaw fossils are referred to the following two genera and three species, including one possible new species: Nanaimoteuthis jeletzkyi and N. yokotai of the order Vampyromorpha, and Paleocirroteuthis sp. nov. (?) of the order Cirroctopodida. The other single lower jaw is seemingly similar to those of modern octopods and teuthids with respect to the shape of the inner lamella, but its order-level assignment could not be determined because of its imperfect preservation. N. jeletzkyi has been described in the Upper Cretaceous fore-arc basin deposits in Hokkaido (Yezo Group) and Vancouver Island, Canada (Nanaimo Group), whereas N. yokotai occurs only in the Yezo Group. These findings, complemented by previous reports of coleoid jaws, gladii, and phragmocones from the Yezo and Nanaimo Groups, demonstrate that a highly diversified, non-belemnitid coleoid fauna including large teuthids had already appeared during the post-Albian Late Cretaceous, in the North Pacific region.  相似文献   

Sulcusina iberica n. ichnogen., n. ichnosp., a new crustacean microcoprolite from the Upper Cretaceous of Spain     

《Cretaceous Research》2017

The new crustacean microcoprolite Sulcusina iberica n. ichnogen., n. ichnosp., is described from the Upper Cretaceous Alarcón Formation (?uppermost Cenomanian to ?lower Coniacian) of the Southern Iberian range. The new ichnogenus is characterized by rod-shaped bodies with parallel-running longitudinal canals (without interconnecting lines) of rounded transverse sections within the symmetry plane. Characteristic is the presence of a central longitudinal furrow (or canal) that extends to the middle of the microcoprolite, without any connection to the laterally grouped canals of usually lower diameter. The latter display a circular outline in transverse sections. Sulcusina n. ichnogen. can be compared to some extant with both Helicerina Brönnimann & Masse and Lercarina Senowbari-Daryan. The new microcoprolite occurs in monotypic grainstones together with some thin-walled miliolids and ostracods ascribed to a peritidal facies.  相似文献   

Early Campanian Corallistidae (lithistid Demospongiae) from the Miechów and Mogilno-Łódź synclinoria,southern and central Poland     

《Cretaceous Research》2017

  相似文献   

New taxa of unusual Dilaridae (Neuroptera) with siphonate mouthparts from the mid-Cretaceous Burmese amber     

《Cretaceous Research》2017

Cretadilar olei gen. et sp. nov. and Burmopsychops groehni sp. nov. (Neuroptera: Dilaridae) are described from the Late Cretaceous (earliest Cenomanian/late Albian) Burmese amber. Their dilarid affinities are supported by two autapomorphies of the family: the reduction of the ligula and the presence of pectinate antennae in males. They are considered to belong to two new subfamilies, Cretanallachiinae subfam. nov. and Cretadilarinae subfam. nov., respectively. These subfamilies are easily distinguished from other dilarids (Dilarinae, Nallachiinae, and Berothellinae) by possessing siphonate mouthparts; however they strongly differ from each other. In particular, the broad gonocoxites 9 of Cretanallachiinae females are not fused to form a distinct ovipositor, and bear long gonostyli, whereas a distinct saber-like ovipositor (short, lacking gonostyli) is present in Cretadilarinae. It is assumed that Cretanallachiinae primarily fed on pollen and Cretadilarinae on the nectar of flowers.  相似文献   

A new weevil,Aepyceratus hyperochus gen. et sp. nov., Aepyceratinae subfam. nov., (Coleoptera; Nemonychidae) in Burmese amber     

《Cretaceous Research》2017

A new weevil, Aepyceratus hyperochus gen. et sp. nov., Aepyceratinae subfam. nov., is described from mid-Cretaceous Burmese amber. The new subfamily differs from the previous Mesozoic subfamilies Brenthorrhininae, Eobelinae, Cretonemonychinae and Paleocartinae by the short lateral pronotal carina, stark convex eyes and basal antennal insertion. From the subfamilies Rhinorhynchinae and Cimberidinae, it is distinguished by the short lateral pronotal carina, exodontous mandibles and basal antennal insertion. The new subfamily differs from the subfamily Idiomacerinae by the distinct clypeolabral suture, elliptical protruding eyes, short antennomere 1, wide tarsi, short lateral carina on the pronotum, and exodontous mandibles.  相似文献   

安徽齐云山晚白垩世恐龙蛋矿物和元素组成及古环境分析   总被引：1，自引：0，他引：1  

姜琴  何情  郑刘根  胡毅 《岩矿测试》2017,36(4):340-349

安徽齐云山新发现的恐龙蛋化石保存完好,是研究该地区晚白垩世恐龙动物群生活环境及绝灭的关键。本文采用粉晶X射线衍射法(XRD)、电感耦合等离子体发射光谱/质谱法(ICP-OES/MS)分析齐云山恐龙蛋壳、蛋核及围岩的宏观矿物及主量、微量元素组成,以探讨齐云山晚白垩世古环境和古气候特征。结果表明:恐龙蛋壳主要矿物组成为方解石和石英,且蛋内外物质矿物组成相似,主要为石英和长石;而元素组成包括常量元素Ca、Na、Mg、K、Al和Fe及微量元素Sr、Zn、Ba、As、Ti、V、Cr、Co、Ni、Cu、Mn、Pb、La、U和Ir,其中Sr在蛋壳中含量的平均值为6199.3×10~(-6),高于河南西峡及广东南雄大部分恐龙蛋壳中的Sr含量,蛋壳中Ir含量的平均值为59.6×10~(-12),Sr和Ir与背景值相比均有明显异常,分析认为是恐龙与外界进行物质交换时吸收有害元素引起的。而As、Mn和Pb的富集及Zn的不足可能使恐龙机体中毒进而灭绝。围岩中Fe含量的增加表明齐云山地区晚白垩世为干旱炎热的气候条件,与Fe呈正相关性的Ir元素随Fe含量的增加而富集,且越靠近K/T界线,围岩中Sr和Ir元素含量越高,这是导致该地区恐龙动物群绝灭的原因之一。此结论为研究齐云山地区恐龙动物群的生活环境提供了依据。  相似文献   

Dinosaur footprint assemblage from the Lower Cretaceous Khok Kruat Formation,Khorat Group,northeastern Thailand     

Shohei Kozu  Apsorn Sardsud  Doungrutai Saesaengseerung  Cherdchan Pothichaiya  Sachiko Agematsu  Katsuo Sashida 《地学前缘(英文版)》2017,8(6):1479-1493

The Khok Kruat Formation is the upper part of the Khorat Group, which consists of upper Lower Cretaceous non-marine sedimentary rocks in northeastern Thailand. Many dinosaur footprints have been known from the upper Lower Cretaceous (Aptian–Albian) Khok Kruat Formation at the Huai Dam Chum (Tha Uthen) site, northeastern Thailand. Approximately 600 tracks occur in thin mudstone layer of the northern part of the outcrop at the Huai Dam Chum track site. Two types of footprints, small-sized theropod and crocodylomorph are imprinted with mud cracks and ripple marks on the thin mud layer. Most of footprints are referred to cf. Asianopodus, and are imprinted by small-sized theropoda, probably ornithomimosauria. Theropod tracks are mainly separated into two groups, Group A and Group B. From ichnological viewpoints, the small-sized theropod track assemblage indicates the herd behaviour and its idiosyncratic group composition. In particular, the histogram of size-frequency measurements of Group A shows the anomalous bimodal distribution. We consider that there are two hypotheses; the first one is due to the male-female difference, and the second is a result of the different growing stage.  相似文献