Terminal cretaceous extinctions in the hell creek area, montana: compatible with catastrophic extinction

Inaccurate stratigraphic correlations in the Hell Creek area, Montana, have led to the assumption that transitional vertebrate faunas (Bug Creek Anthills) exist in the latest Cretaceous, refuting a catastrophic turnover at the Cretaceous-Tertiary boundary. Establishment of the transitional faunas in Paleocene channels that cut down through the Cretaceous-Tertiary boundary renders the terrestrial faunal record compatible with the marine record and with catastrophic extinction.     

A theropod dinosaur embryo and the affinities of the flaming cliffs dinosaur eggs

An embryonic skeleton of a nonavian theropod dinosaur was found preserved in an egg from Upper Cretaceous rocks in the Gobi Desert of Mongolia. Cranial features identify the embryo as a member of Oviraptoridae. Two embryo-sized skulls of dromaeosaurids, similar to that of Velociraptor, were also recovered in the nest. The eggshell microstructure is similar to that of ratite birds and is of a type common in the Djadokhta Formation at the Flaming Cliffs (Bayn Dzak). Discovery of a nest of such eggs at the Flaming Cliffs in 1923, beneath the Oviraptor philoceratops holotype, suggests that this dinosaur may have been a brooding adult.     

A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea

Upper Triassic rocks in northwestern Argentina preserve the most complete record of dinosaurs before their rise to dominance in the Early Jurassic. Here, we describe a previously unidentified basal theropod, reassess its contemporary Eoraptor as a basal sauropodomorph, divide the faunal record of the Ischigualasto Formation with biozones, and bracket the formation with (40)Ar/(39)Ar ages. Some 230 million years ago in the Late Triassic (mid Carnian), the earliest dinosaurs were the dominant terrestrial carnivores and small herbivores in southwestern Pangaea. The extinction of nondinosaurian herbivores is sequential and is not linked to an increase in dinosaurian diversity, which weakens the predominant scenario for dinosaurian ascendancy as opportunistic replacement.     

Feather quill knobs in the dinosaur Velociraptor

Some nonavian theropod dinosaurs were at least partially covered in feathers or filamentous protofeathers. However, a complete understanding of feather distribution among theropod dinosaurs is limited because feathers are typically preserved only in lagerst?tten like that of Solnhofen, Germany or Liaoning, China. Such deposits possess clear taphonomic biases toward small-bodied animals, limiting our knowledge regarding feather presence in larger members of feathered clades. We present direct evidence of feathers in Velociraptor mongoliensis based on the presence of quill knobs on the posterior forearm. This report of secondaries in a larger-bodied, derived, and clearly flightless member of a nonavian theropod clade represented by feathered relatives is a substantial contribution to our knowledge of the evolution of feathers.     

Developmental plasticity in the life history of a prosauropod dinosaur

Long-bone histology indicates that the most common early dinosaur, the prosauropod Plateosaurus engelhardti from the Upper Triassic of Central Europe, had variable life histories. Although Plateosaurus grew at the fast rates typical for dinosaurs, as indicated by fibrolamellar bone, qualitative (growth stop) and quantitative (growth-mark counts) features of its histology are poorly correlated with body size. Individual life histories of P. engelhardti were influenced by environmental factors, as in modern ectothermic reptiles, but not in mammals, birds, or other dinosaurs.     

A long-snouted predatory dinosaur from africa and the evolution of spinosaurids

Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.     

长江口九段沙湿地潮沟鱼类组成及其多样性

长江口九段沙湿地潮沟鱼类组成有着典型的长江口鱼类区系特征,为了解该湿地尤其是湿地潮沟鱼类的组成和多样性,在2009至2010年间对九段沙湿地的上沙、中沙和下沙潮沟进行了5次调查,共捕获鱼类3 637尾,105 158.9 g,42种,分别隶属于11目、22科。其中种类和个体数均以鲈形目居多,有20种,3 433尾,其次是鲤形目7种,49尾和鲱形目5种,33尾;海水、河口、淡水、洄游4种生态类型的种类所占百分比分别为26.19%、40.48%、23.81%、9.52%,而河口性鱼类的个体数和总湿重占绝对优势,分别占总量的94.4%和96.3%。上沙、中沙和下沙的渔获量分别为21种742尾51 025.2 g、30种1 007尾29 427.5 g、20种1 888尾24 696.2 g,均是河口性鱼类占绝对优势;就相对多度、相对重要性指数来看斑尾刺虾虎鱼（Acanthogobius ommaturus）、（Liza haermatochiel）、四指马鲅（Eleutheronema tetradactylu）这3个种类为优势种,尤以斑尾刺虾虎鱼占绝对优势;就多样性来看,上沙的多样性水平较九段沙湿地的整体水平低,鱼类种类相对较少。     

煅烧贝壳粉果蔬清洗剂对农药降解性能的研究

[目的]研究不同用量的煅烧贝壳粉水溶液对不同成分农药的降解效率,优化煅烧贝壳粉果蔬清洗剂的浓度配比并为不同农药降解效率的研究提供参考。[方法]采用气相色谱质谱法检测了煅烧贝壳粉水溶液对敌敌畏、久效磷、灭线磷等14种农药的降解情况,选取的贝壳粉水溶液浓度为0．5 g／L,降解时间为5 min,考察了0．5、1．0、3．05、．0 mL 4个不同用量的煅烧贝壳粉水溶液对于不同农药残留的降解效果。[结果]研究发现,降解效率随着贝壳粉水溶液用量的增加而提高,其中贝壳粉对有机磷类农药和氨基甲酸酯类农药的降解作用相对突出,尤其是对久效磷、敌敌畏和甲萘威的降解作用最为明显,仅加入0．5 mL浓度为0．5 g／L的贝壳粉水溶液就可降解50％以上,当加入5．0 mL时降解率超过80％,甚至对久效磷的降解率超过95％;而对菊酯类农药的降解能力较差,加入5．0 mL浓度为0．5 g／L的贝壳粉水溶液时,降解率在40％～60％。[结论]研究表明,煅烧贝壳粉果蔬清洗剂对大多数农药有较为明显的降解作用,可以用于去除水果蔬菜表面农药残留。     

Mammal population losses and the extinction crisis

The disappearance of populations is a prelude to species extinction. No geographically explicit estimates have been made of current population losses of major indicator taxa. Here we compare historic and present distributions of 173 declining mammal species from six continents. These species have collectively lost over 50% of their historic range area, mostly where human activities are intensive. This implies a serious loss of ecosystem services and goods. It also signals a substantial threat to species diversity.     

Geomagnetic polarity change and faunal extinction in the southern ocean

Paleomnlagnietic polarity changes have been detected in nine deep-sea sedimentary cores (from the Pacific-Antarctic Basin) in which an extinction horizon of a radiolarian assemblage was previously independently determined. The depths of the polarity change 0.7 million years ago and the faunal boundary are closely correlated, confirming that the faunal extinction was locally virtually synchronous. Although the reason for the faunal extinction is unknown. the possibility of causal relationships between faunal extinction and factors directly involved with sedimentation rate, sedimentation rate variation, and sediment type appears to be excluded.     

Nonrandom extinction and the loss of evolutionary history

The hierarchical nature of phylogenies means that random extinction of species affects a smaller fraction of higher taxa, and so the total amount of evolutionary history lost may be comparatively slight. However, current extinction risk is not phylogenetically random. We show the potentially severe implications of the clumped nature of threat for the loss of biodiversity. An additional 120 avian and mammalian genera are at risk compared with the number predicted under random extinction. We estimate that the prospective extra loss of mammalian evolutionary history alone would be equivalent to losing a monotypic phylum.     

Lancefield swamp and the extinction of the Australian megafauna

Excavations into the Australian swamp of Lancefield show that a bone bed dated at 26,000 years ago contains perhaps 10,000 giant extinct animals. Associated artifacts suggest that humans were in the area, but the direct cause of death of the animals is, on present evidence, not explicable. Such a recent date for the classic megafauna shows that it was living together with humans for at least 7000 years in southeast Australia. This enduring association argues against a catastrophic and rapid overkill in the Australian Pleistocene.     

Eyeball retraction: classical conditioning and extinction in the albino rabbit

A comparison of the percentage-performance curve of a classical conditioning group with those of three control groups provided unequivocal evidence of successful conditioning of the retractor bulbi response to an auditory conditioned stimulus.     

Geographic variation in the molluscan recovery from the end-cretaceous extinction

Biotic recovery patterns after the end-Cretaceous mass extinction differ among the molluscan faunas of the North American Gulf Coast, northern Europe, northern Africa, and Pakistan and northern India. In contrast to the Gulf Coast, the other three regions lack a rapid expansion and decline of "bloom taxa" and have lower proportions of invaders early in the recovery phase. The anomalous Gulf Coast patterns, distinct from extratropical Europe and the tropical regions, provide evidence for the biogeographic and macroevolutionary complexity of biotic recoveries and may have implications for present-day biotas.     

Nannoplankton extinction and origination across the Paleocene-Eocene Thermal Maximum

The Paleocene-Eocene Thermal Maximum (PETM, approximately 55 million years ago) was an interval of global warming and ocean acidification attributed to rapid release and oxidation of buried carbon. We show that the onset of the PETM coincided with a prominent increase in the origination and extinction of calcareous phytoplankton. Yet major perturbation of the surface-water saturation state across the PETM was not detrimental to the survival of most calcareous nannoplankton taxa and did not impart a calcification or ecological bias to the pattern of evolutionary turnover. Instead, the rate of environmental change appears to have driven turnover, preferentially affecting rare taxa living close to their viable limits.     

Decoupled plant and insect diversity after the end-Cretaceous extinction

Food web recovery from mass extinction is poorly understood. We analyzed insect-feeding damage on 14,999 angiosperm leaves from 14 latest Cretaceous, Paleocene, and early Eocene sites in the western interior United States. Most Paleocene floras have low richness of plants and of insect damage. However, a low-diversity 64.4-million-year-old flora from southeastern Montana shows extremely high insect damage richness, especially of leaf mining, whereas an anomalously diverse 63.8-million-year-old flora from the Denver Basin shows little damage and virtually no specialized feeding. These findings reveal severely unbalanced food webs 1 to 2 million years after the end-Cretaceous extinction 65.5 million years ago.