Podocarpus from the eocene of north america

A few leafy gymnosperm shoots were found in Eocene deposits of southeastern North America. Similar fossil material from Tertiary deposits in North America has been identified as Taxodium, Taxites, and Sequoia. This new fossil material is not related to these genera but belongs to Podocarpus section Stachycarpus. This is the first fossil record of this section in North America.     

An ictidosaur fossil from north america

Teeth of a North American ictidosaur, Pachygenelus milleri, n. sp., found in the Upper Triassic Dockum Group of Texas, indicate that it is very similar to Pachygenelus monus of South Africa and Chaliminia musteloides of South America. The presence of a Gondwana element in the Northern Hemisphere attests to the ease of dispersal of the Late Triassic vertebrates through Pangea. Ictidosaurs are small, highly advanced, carnivorous cynodonts that display a mosaic of reptilian and mammalian features in the masticatory apparatus. They were contemporaneous with early mammals and probably closely related to them.     

A fish from the upper cambrian of north america

Phosphatic dermal fragments of Anatolepis, interpreted as a heterostracan fish (class Agnatha), have been discovered in the Deadwood Formation of Late Cambrian age in northeastern Wyoming. This discovery extends back the age of the earliest known vertebrate fossils by approximately 40 million years. Other occurrences of Anatolepis in North America, Greenland, and Spitzbergen show that these fish had a widespread geographic distribution in Late Cambrian and Early Ordovician marine environments.     

Mammalian evolution and the great american interchange

A reciprocal and apparently symmetrical interchange of land mammals between North and South America began about 3 million years ago, after the appearance of the Panamanian land bridge. The number of families of land mammals in South America rose from 32 before the interchange to 39 after it began, and then back to 35 at present. An equivalent number of families experienced a comparable rise and decline in North America during the same interval. These changes in diversity are predicted by the MacArthur-Wilson species equilibrium theory. The greater number of North American genera (24) initially entering South America than the reverse (12) is predicted by the proportions of reservoir genera on the two continents. However, a later imbalance caused by secondary immigrants (those which evolved from initial immigrants) is not expected from equilibrium theory.     

First record of giant anteater (xenarthra, myrmecophagidae) in north america

A right metacarpal III represents the first North American record of the giant anteater (Myrmecophaga tridactyla). Recovered in northwestern Sonora, Mexico, with a rich vertebrate fauna of early Pleistocene (Irvingtonian) age, it belongs to a cohort of large mammals that dispersed from South America to North America along a savanna corridor. Presumably habitat and climatic changes have subsequently driven this mammalian family more than 3000 kilometers back into Central America from its former expansion into temperate North America.     

Global assessment of organic contaminants in farmed salmon

The annual global production of farmed salmon has increased by a factor of 40 during the past two decades. Salmon from farms in northern Europe, North America, and Chile are now available widely year-round at relatively low prices. Salmon farms have been criticized for their ecological effects, but the potential human health risks of farmed salmon consumption have not been examined rigorously. Having analyzed over 2 metric tons of farmed and wild salmon from around the world for organochlorine contaminants, we show that concentrations of these contaminants are significantly higher in farmed salmon than in wild. European-raised salmon have significantly greater contaminant loads than those raised in North and South America, indicating the need for further investigation into the sources of contamination. Risk analysis indicates that consumption of farmed Atlantic salmon may pose health risks that detract from the beneficial effects of fish consumption.     

Specification of jaw subdivisions by Dlx genes

The success of vertebrates was due in part to the acquisition and modification of jaws. Jaws are principally derived from the branchial arches, embryonic structures that exhibit proximodistal polarity. To investigate the mechanisms that specify the identity of skeletal elements within the arches, we examined mice lacking expression of Dlx5 and Dlx6, linked homeobox genes expressed distally but not proximally within the arches. Dlx5/6-/- mutants exhibit a homeotic transformation of lower jaws to upper jaws. We suggest that nested Dlx expression in the arches patterns their proximodistal axes. Evolutionary acquisition and subsequent refinement of jaws may have been dependent on modification of Dlx expression.     

从庭院种植的趋势展望梅花在加拿大西海岸的引种开发

梅花是中国人所熟悉且历史悠久的传统名花。其少数品种尽管在北美市场流传已久,但却从未受到西方人重视,因而迄今知之者甚少。本文从影响加拿大民众总体花卉消费的4种重要因素(文化传统和市政立法、住宅可绿化面积、经济环境状况、节日花卉消费)入手,分析了在诸因素的制约下,加拿大园林植物消费出现的新动向,即由纯观赏性植物向食用性植物转变、从中大型植物向矮生型植物转变、由常规型植物向独特型植物转变。在以上转变中,梅花本身的特点和习性,奠定了其在加拿大花卉消费市场中潜在的地位和前景。通过各种革新栽培和推广技术,希望加拿大西海岸地区能在不久的将来成为梅花生根开花的第二故乡。     

Management of Colorado potato beetle in invasive frontier areas

Colorado potato beetle(CPB) is one of the most devastating invasive insects and it is native to North America. It feeds on several wild species of the genus Solamum, such as S. elaeagnifolium and S. rostratum Dunal, and is one of the major pests of potato and eggplant. Beginning in the early 19 th century, CPB has rapidly spread across North America, Europe, and Central Asia. CPB was first reported to invade Xinjiang of China in 1993 and it was effectively controlled in Mori County. Since 2013, CPB has also been found in Jilin and Heilongjiang in Northeast China, and it likely migrated to these provinces from Russia. Thus, China has become the frontier for the global CPB spread, and risk management and monitoring systems for this pest are urgently needed. Here, we summarize pest management methods that are used in areas at the frontier of the CPB invasion, and put forward frameworks for further preventing and controlling of the spread of CPB. The management methods for CPB can also serve as an example for the control of invasive species mitigation in frontier areas.     

Multiple transatlantic introductions of the western corn rootworm

The invasion of Europe by the western corn rootworm, North America's most destructive corn pest, is ongoing and represents a serious threat to European agriculture. Because this pest was initially introduced in Central Europe, it was believed that subsequent outbreaks in Western Europe originated from this area. Using model-based Bayesian analyses of the genetic variability of the western corn rootworm, we demonstrate that this belief is false: There have been at least three independent introductions from North America during the past two decades. This result raises questions about changing circumstances that have enabled a sudden burst of transatlantic introductions.     

The archeology of alaska and the peopling of america

The proposed existence of a biotically productive tundra-steppe on the exposed Bering Land Bridge of the late Pleistocene aids conceptualization of the migrations of early Asian hunters. But clear knowledge of the human occupants of north-westernmost America before 11,000 years ago is elusive. Evidence indicates that at that time the Alaskan peoples had a culture generally based on microliths that, while obviously derived from Asia, were not sufficiently similar to the tools of the earliest widely distributed hunters of more southerly North America to support any direct and close relation between the two cultures.     

北美农业合作社发展新动向及其启示王

在对国内外关于北美农业合作社的资料进行系统梳理、总结和分析的基础上,对北美农业合作社发展的新动向、新一代合作社和有限合作组织进行研究。结果表明：北美农业合作社通过一系列组织制度创新,延长了产业链条,增强了市场竞争力;合作社对基本原则进行了修正,允许外部投资者加入,并通过完善相关制度维护了惠顾者的利益。借鉴其经验,我国农民合作社应积极吸纳外部投资者加入合作社,增强合作社竞争力;向产业链下游延伸,提升合作社农产品增值能力;完善合作社的治理结构和盈余分配制度,协调好投资成员与惠顾成员间的关系。     

Orbitolina, a cretaceous larger foraminifer, from flemish cap: paleoceanographic implications

The Tethyan larger foraminiferal genus Orbitolina has been found in the easternmost part of the western North Atlantic continental shelf at 46 degrees 30'N. All other known occurrences of the genus in North America are south of 33 degrees N. The species is Orbitolina conoidea Gras; its abundance in a grainsupported limestone indicates a tropical neritic environment and precludes the influence of Arctic waters in the Flemish Cap region in Early or Middle Cretaceous times.     

Invasive plants versus their new and old neighbors: a mechanism for exotic invasion

Invading exotic plants are thought to succeed primarily because they have escaped their natural enemies, not because of novel interactions with their new neighbors. However, we find that Centaurea diffusa, a noxious weed in North America, has much stronger negative effects on grass species from North America than on closely related grass species from communities to which Centaurea is native. Centaurea's advantage against North American species appears to be due to differences in the effects of its root exudates and how these root exudates affect competition for resources. Our results may help to explain why some exotic species so successfully invade natural plant communities.     

Mammalian dispersal at the Paleocene/Eocene boundary

A profound faunal reorganization occurred near the Paleocene/Eocene boundary, when several groups of mammals abruptly appeared on the Holarctic continents. To test the hypothesis that this event featured the dispersal of groups from Asia to North America and Europe, we used isotope stratigraphy, magnetostratigraphy, and quantitative biochronology to constrain the relative age of important Asian faunas. The extinct family Hyaenodontidae appeared in Asia before it did so in North America, and the modern orders Primates, Artiodactyla, and Perissodactyla first appeared in Asia at or before the Paleocene/Eocene boundary. These results are consistent with Asia being a center for early mammalian origination.     

Locomotion in moles (insectivora, proscalopidae) from the middle tertiary of north america

The locomotion of proscalopid moles, an extinct group restricted to North America, differed from that of other animals. Analysis of a newly discovered and relatively complete and articulated skeleton shows that the digging technique of proscalopids involved a combination of motions that has not been observed in modern fossorial insectivores. The many anatomical peculiarities of proscalopids are related to their specialized digging technique and justify their assignment to a new family of insectivores, the Proscalopidae.     

Strontium-90 and cesium-137 in North American milk

The strontium-90 and cesium-137 concentrations in powdered milk in North America vary roughly with the specific activity of rain. The Sr(90)/Cs(137). ratios in over 800 powdered milk samples taken from 60 stations in North America from 1957-60 have a standard deviation of only 44 percent.     

Diamonds in an upper mantle peridotite nodule from kimberlite in southern wyoming

Diamonds in a serpentinized garnet peridotite nodule from a diatreme in southern Wyoming are the first known occurrence in an upper mantle peridotite xenolith from a kimberlite intrusion in North America as well as the second authenticated occurrence of diamonds from kimberlite pipes in North America. The nodule is believed to have come from a section of depleted (partially melted) lherzolite at a depth of 130 to 180 kilometers.     

Confirmation of the Carolina slate belt as an exotic terrane

An assemblage of Middle Cambrian Atlantic faunal province trilobites has been found in the rocks of the Carolina slate belt near Batesburg, South Carolina. Geologic and paleomagnetic data suggest that the Carolina slate belt and the adjacent Charlotte belt constitute an exotic terrane that was accreted to North America in early to middle Paleozoic time.     

Schopf, maclure, werner, and the earliest work on american geology

Sch?pf produced the first substantial report on the geology of North America, a work that has long suffered unjustified oblivion. In at least one feature this treatise is superior to that of Maclure (the"Father of American Geology")- Sch?pf attempted interpretation whereas Maclure did not. The suggestion is here offered that MacLure, who adopted Werner's classification of the stratigraphic succession, was simply shying away from Wernerian interpretation because he did not like the looks of it.