A new marsilealean fern species from the Early Cretaceous of Jordan

Leaflets of Marsileaceae are described from the Albian (Early Cretaceous) strata of Jordan. The fossils are from the Jarash Formation (Kurnub Group) and are found in fluvial sediments along with water lily leaves. The small wedge-shaped leaves have dichotomous veins that anastomose and form a marginal vein. Based on comparisons to living genera, Marsileaceaephyllum mahisensis Hu, Taylor, Brenner et Basha, n. sp., is most similar to Marsilea, in particular, with terrestrial leaflet forms; yet, it is distinct from living and fossil species by its small size and the few dichotomously branched middle veins that have a monopodial course. In addition, a single similar-veined smaller leaf with a retuse apex is thought to be a juvenile leaf of the same species. This is the first megafossil evidence of the family from Africa/Arabian Peninsula.     

Theropod dinosaurs from the Albian–Cenomanian Wayan Formation of eastern Idaho

The record of terrestrial vertebrates in the upper Albian to Cenomanian Wayan Formation of Idaho is sparse, with most fossils recovered belonging to the small orodromine neornithischian Oryctodromeus cubicularis and the maniraptoran ootaxon Macroelongatoolithus carlylei. Here we report on a diversity of theropod forms now recognised from various isolated teeth, vertebrae, eggs and eggshell. Theropods recognised from isolated teeth include a large possible tyrannosauroid, a small tyrannosauroid, dromaeosaurids, and indeterminate theropods. A possible neovenatorid and indeterminate theropods are recognised from isolated vertebrae. A giant oviraptorosaur is indicated by the presence of rare eggs and common eggshell accumulations referred to Macroelongatoolithus. While these remains are admittedly meager, their presence indicates that a substantial diversity of theropods existed in the Albian to Cenomanian environments of southeastern Idaho. The Wayan theropod assemblage is among the most diverse reported for this time period in North America, and represents a transitional assemblage resembling that of the later Late Cretaceous.     

Comptoniaster adamsi nov. sp. (Echinodermata, Asteroidea) from the middle Cretaceous of Texas and its phylogenetic position

Comptoniaster adamsi nov. sp. (Asteroidea, Valvatida, Goniasteridae) is described from the middle Cretaceous (Cenomanian-Turonian) Britton Formation of northcentral Texas, USA. The new species provides the focus for an exploratory cladistic analysis of Mesozoic asteroids of the Comptoniaster-Tylasteria Group sensu G. Breton. The systematics of Mesozoic goniasterids has relied heavily on the morphology of marginal ossicles, which generally are the best-preserved elements of the skeleton. Unfortunately, marginal ossicular data are scanty for most species because ossicles tend to be morphologically simple yet varied even within individuals, and few even partially articulated specimens are available to provide more comprehensive information. Further, both plesiomorphy and homeomorphy have been important. Because of limited available data, phylogenetic reconstruction here is preliminary. Nevertheless, a number of taxon groupings recognized in the literature are recovered, and stratigraphic distribution provides some support for results. Data unfortunately are particularly incomplete for species of Comptoniaster, the focus of the study. Comptoniaster adamsi nov. sp. clustered with three other species assigned to the genus, including the type, all Cretaceous in age. Jurassic species of Comptoniaster are more widely distributed in the analysis, perhaps reflecting an early stage in diversification or perhaps suggesting the need for species assignment reassessment, but also reflecting the limited available data.     

Les gastéropodes et le bivalve Pinna (Pinna) cretacea cretacea (Schlotheim) des dépôts albiens des Rides sud-rifaines (région de Moulay Idriss Zerhoun,nord Maroc)

The « Marnes et calcaires lumachelles à huîtres » Formation (late Albian–early Cenomanian) of the South Riffian Ridges, rich in bivalves, yielded in levels of upper Albian some gastropod specimens including: Ampullina aff. uchauxiensis Cossmann, Ampullina indet., Aporrhaidae indet., Calliomphalus cf. orientalis (Douvillé), Cerithioidea indet., Mrhilaia indet.,?Neogastropoda indet., Pleurotomaria indet., Pseudamaura subbulbiformis (d’Orbigny), Tylostoma aff. globosum Sharpe, and a rare bivalve, Pinna (Pinna) cretacea cretacea (Schlotheim). The two underlying formations « Conglomérat et marnes sableuses » and « Calcaires gréseux » (early to middle Albian?), poor in macrofauna, yielded rare Nerineopsis aff. excavata (Brongniart) and Turritella indet. These species are reported for the first time in the Moroccan Cretaceous deposits.     

松辽盆地阿尔必期微体浮游植物新属种

该文描述了松辽盆地中白垩世阿尔必期泉头组三段的微体浮游植物化石1新属7新种,隶属于微咸水沟鞭藻类2属5新种(含4新亚种),淡水绿藻1属1种和疑源类1新属1新种。并对沟鞭藻 Ngktericysta Bint,1986进行了修订。     

新疆塔里木盆地早白垩世克孜勒苏群孢粉组合

基于新疆塔里木盆地西南区和东南区下白垩统克孜勒苏群发现的孢子花粉57属96种的研究,建立了克孜勒苏群下亚旋回和上亚旋回孢粉组合,并根据孢粉组合讨论了地层时代。克孜勒苏群孢粉组合以松杉目的优势、真蕨目海金沙科的显赫和原始被子植物的出现为特征。克孜勒苏群下亚旋回孢粉组合与欧洲韦尔登期(陆相尼欧克姆期)和北美巴列姆期孢粉组合可以对比,克孜勒苏群上亚旋回孢粉组合与欧亚大陆、北美和澳大利亚阿普第期至阿尔必期孢粉组合可以对比。根据孢粉学证据,克孜勒苏群下亚旋回应属于尼欧克姆期,或赫特里夫期至巴列姆期,克孜勒苏群上亚旋回应归于阿普第期至阿尔必期。     

粤西怀集盆地白垩系马屋组的介形类化石

依据闸岗剖面地表及钻井样品的分析鉴定,粤西怀集盆地白垩纪闸岗群马屋组产介形类化石10属17种,本文描述其中9属14种,包括1新种。介形类组合以Eucypris最繁盛,次为Ziziphocypris和Darwinula,称Eucypris hubeiensis-Ziziphocypris simakovi-Darwinula leguminella组合。马屋组与湖北贾店组的介形类组合面貌非常相似,可以进行对比,层位大体相当,其时代应属早白垩世最晚期(Albian)-晚白垩世早期(Cenomanian)。     

Facies of sunken early cretaceous atoll reefs and their capping Late Albian drowning succession (Northwestern Pacific)

Summary Since first described in detail byHamilton (1956), the causes and timing of the drowning of several hundred guyots in the northwestern Pacific is a puzzling question. Thus, the northwestern Pacific is one of the key areas in deciphering the demise of flat-topped platforms throughout the earth’s history. Based on older paleontological data and the newly found shallow-water benthic foraminifera, the atoll reefs probably had a major period of vertical aggradation during the Barremian and the Aptian into the Late Albian depending on the stage of atoll development (type of guyot). New sedimentologic and stratigraphic data suggest a strong fall in sea level, leading to karstification and the formation of lowstand fringing reefs, prior to an even rapid rise of greater amplitude in the Late AlbianRotalipora appenninica zone ultimately causing drowning. After climatic relaxation, a sea level rise led to the final formation of small barrier reefs, rimming the top of many guyots in the Japanese Group, the Wake Group and the Mid-Pacific Mountains. They can be interpreted as “give-up” structures indicating a final shallow-water carbonate production on top of the atolls during drowning. The facies of the syn- and post-drowning sediments on the guyot tops are strikingly similar even when vast distances apart. This and the biostratigraphic data suggest a synchronous drowning of many seamounts investigated up to now. Biotic composition and facies of the final Albian reefs are very similar to Albian caprinid-dominated reefs in the Caribbean region, indicating comparable environmental controls. In the case of the northwestern Pacific guyots, the simultaneous demise of reefs could be due to a short-term cooling event in the Late Albian, connected with a strong regressive-transgressive cycle with an amplitude of about 180 m. This event is also known from the Tethys and the Atlantic. Climatic disturbances triggering short-term cooling and inducing a high amplitude regressive-transgressive sea level cycle, might be responsible not only for the Late Albian event, but also perhaps for other reef drownings throughout the earth’s history.     

Early development of the anterior body region of the grey widow spider Latrodectus geometricus Koch, 1841 (Theridiidae, Araneae)

We document the early morphogenesis of Latrodectus geometricus, particularly of the anterior body region. Significant changes in the development of the external prosomal structures revealed with scanning electron microscopy (SEM) images include: (1) reorganisation of each pre-cheliceral lobe by subdivision and internalisation of its central area; (2) shortening of the ventro-median bridge connecting the pre-cheliceral lobes and its eventual disappearance; (3) appearance and expansion of a prospective mouth region between the pre-cheliceral lobes with a recessed median area surrounded by lip-like borders, the anterior lip-part developing into the hypostome; (4) reduction of the mouth region to an area around the hypostome and the lip-like latero-posterior border of the mouth opening; (5) change of the position of the mouth region from anterior to the insertions of the chelicerae to posterior to them; (6) eventual shortening of the mouth opening to a slit overhung by the hypostome; (7) origination of the prosomal shield from the anterior margin of the pre-cheliceral lobes and the tergal portions of the four posterior-most prosomal segments; and (8) expansion of a ‘ventral sulcus’ from the cheliceral to the fifth opisthosomal segment separating the sides of these segments. Embryonic features are compared across the Chelicerata and discussed briefly in a phylogenetic context.