Earliest known marsupials

The infraclass Metatheria has not been reported from deposits predating the mid-Cretaceous. Fossil material just recovered from Albian deposits in northcentral Texas has definite characteristics of the family Didelphidae and is submitted as being from the oldest known marsupials. The same locality has also produced remains referable to Eutheria, demonstrating a somewhat earlier divergence of these two important groups than was known before.     

Ages of fossil penguins in new zealand

The age of a New Zealand specimen generally believed to represent the oldest known penguin, hitherto considered early Eocene (Heretaungan), has been restudied by the New Zealand Geological Survey and is early Miocene. The oldest known penguins are from the late Eocene. The reported great range of a single species, Palaeeudyptes antarcticus, from late Eocene to late Oligocene or early Miocene (Kaiatan to Waitakian) is not acceptable. Dating of some other specimens is less precise than previously reported.     

South american geochronology: radiometric time scale for middle to late tertiary mammal-bearing horizons in patagonia

Radiometric (potassium-argon) age determinations for basalts and tuffs associated with middle to late Tertiary mammal-bearing horizons in Patagonia, southern Argentina, permit refinement of boundaries and hiatuses between beds of Deseadan (early Oligocene) through Friasian (middle to late Miocene) age. At two localities beds of Deseadan age are overlain by basalts, which gave dates of 33.6 and 35.4 million years ago; 34.0 million years ago is tentatively accepted as a terminal date for known Deseadan. At several localities beds of Colhuehuapian age are underlain by basalts, which gave dates ranging from 28.8 to 24.3 million years ago; 25.0 million years is tentatively taken as a basal age for known Colhuehuapian. The paleontological hiatus between known Deseadan and known Colhuehuapian is thus in the order of 9.0 million years. Two tuffs from the Santa Cruz Formation (Santacrucian) gave ages of 21.7 and 18.5 million years. Plagioclase and biotite concentrates of an ignimbrite from the Collón Curá Formation (Friasian) gave ages ranging from 15.4 to 14.0 million years.     

Paleontology. New feathered dino firms up bird links

Last week, Chinese scientists presented evidence from a new specimen dug up in Liaoning Province that they say strengthens the case for the bird-dinosaur link. The finding, one of several fossils displayed at a meeting here, is the third known specimen of a strange creature known as Caudipteryx which, unlike any other known dinosaur fossil, shows the unmistakable imprints of feathers. The researcher who described the new specimen at the meeting has identified 16 characteristics of the new fossil that are more similar to dinosaurs than to early birds, reinforcing the views of most Western scientists.     

Fossil mammals from baja california: new evidence on early tertiary migrations

Ungulates belonging to the family Barylambdidae were found in the same geologic unit with, but stratigraphically above, a specimen assigned to the Tillodontia and above several molars of the perissodactyl cf. Hyracotherium sp. This arrangement is unusual, as in the well-documented faunas from the Rocky Mountain Region Barylambdidae are known only from the Paleocene, Tillodontia from the Paleocene and Eocene, while Hyracotherium is known only from the Eocene. The expected stratigraphic order would be, from lowest to highest, Barylambdidae, Tillodontia, and Hyracotherium. It is suggested that the Baja California assemblage is late Paleocene on the basis of the generalized molars of cf. Hyracotherium sp. and the characters of cf. Esthonyx sp.     

作物杂种优势遗传研究进展

杂种优势已经在许多作物上广泛应用,但对杂种遗传基础的认识仍显不足。显性和超显性假说是传播最广的两种学术观点,也得到一些DNA分子标记研究结果的支持。现在已经明确杂种优势是由多个基因共同控制的,基因位点间的上位性互作发挥了重要作用,存在控制杂种优势的遗传网络。这些研究将为有效预测杂种优势和利用分子设计更好地利用杂种优势奠定了良好基础。     

Humoral agent from calf lung producing pulmonary arterial vasoconstriction

Saline washings obtained in vivo from the lung of young calves produce pulmonary hypertension upon intrayascular (systemic or pulmonary) injection into either the dog or the calf. This pulmonary hypertension is produced by vasoconstriction of small, precapillary pulmonary vessels. The active agent, pulmonary arterial constrictor substance, differs chemically and physiologically from other substances which have been investigated with respect to vasomotor activity in the pulmonary circulation. Although the chemical nature of the active agent is not known it appears to have a relatively large molecular weight. Whether this agent plays a role in the physiological regulation of the pulmonary circulation is not known.     

Prediction and theory evaluation: the case of light bending

Is a theory that makes successful predictions of new facts better than one that does not? Does a fact provide better evidence for a theory if it was not known before being deduced from the theory? These questions can be answered by analyzing historical cases. Einstein's successful prediction of gravitational light bending from his general theory of relativity has been presented as an important example of how "real" science works (in contrast to alleged pseudosciences like psychoanalysis). But, while this success gained favorable publicity for the theory, most scientists did not give it any more weight than the deduction of the advance of Mercury's perihelion (a phenomenon known for several decades). The fact that scientists often use the word "prediction" to describe the deduction of such previously known facts suggests that novelty may be of little importance in evaluating theories. It may even detract from the evidential value of a fact, until it is clear that competing theories cannot account for the new fact.     

The works of living social insects as pseudofossils and the age of the oldest known metazoa

Living organisms are known to create structures in ancient rocks that are indigenous but not primary and that have been mistaken for fossils. Examination of burrows recently reported as fossils from 10(9)-year-old sedimentary rocks indicates that they are not the same age as the rocks but were probably made by termites working down after water. The burrows are partially filled with material from a modern lateritic surface from which they descend into steeply dipping, decomposed silt-stones of the Zambian Copperbelt. In fact, no authentic record of Metazoa that are demonstrably coeval with rocks older than 680 million years is known.     

Heat flux anomalies in Antarctica revealed by satellite magnetic data

The geothermal heat flux is an important factor in the dynamics of ice sheets; it affects the occurrence of subglacial lakes, the onset of ice streams, and mass losses from the ice sheet base. Because direct heat flux measurements in ice-covered regions are difficult to obtain, we developed a method that uses satellite magnetic data to estimate the heat flux underneath the Antarctic ice sheet. We found that the heat flux underneath the ice sheet varies from 40 to 185 megawatts per square meter and that areas of high heat flux coincide with known current volcanism and some areas known to have ice streams.     

崂山奶山羊分子系谱的构建及家系遗传特征分析

 【目的】通过微卫星DNA标记技术对已知系谱记录的试验群体构建分子系谱,验证崂山奶山羊与原有系谱记录的一致性,探讨影响亲权鉴定的因素,摸清家系的遗传特征,为群体的保种和遗传管理提供科学依据。【方法】从25个微卫星DNA标记中筛选出12个高多态性的遗传标记,对已知系谱记录的212只崂山奶山羊,利用Cervus vs 2.0软件进行亲权分析,利用Pedigraph vs 2.2软件构建试验群体的分子系谱,利用Molkin vs 3.0、MEGA4和GeneClass2软件对所构建家系的遗传特征及系统发育关系进行分析。用SPSS vs 16软件对每个位点的排除概率（EP）与多态信息含量（PIC）、期望杂合度（He）、观察杂合度（Ho）、等位基因数（K）等多态性参数的相关性进行分析,分析不同位点数及信息来源对亲权鉴定准确性的影响。【结果】12个微卫星DNA遗传标记的多态信息含量均为高度多态（PIC≥0.5）,平均为0.687,平均等位基因数为5.75个,期望杂合度平均为0.730;在父本已知的基础上进行母子亲权鉴定,置信度在95%以上的累积排除概率为0.9998,最终从80个候选母亲、祖母中找出了115个后裔的母亲、祖母,发现3个个体与原有系谱记录不相符,符合度达到98.58%,构建了2个以父系为基础的家系及群体分子系谱图。排除概率与PIC相关系数最大（0.99以上）,与K相关系数最小（0.67）。使用8个位点可使CEP2达到99.73%以上。【结论】所选12个微卫星标记可用于崂山奶山羊试验群体的亲权鉴定及分子系谱构建;所构建家系具有较好的遗传基础,家系间及家系内具有较高的遗传变异。     

从土壤中分离的410株苏云金芽孢杆菌的鉴定

对从中国２０个省（区）采集的１５４２个土壤样品中分离的４１０株苏云金芽孢杆菌进行了血清学鉴定。结果表明，２１８株（５３．２％）属于已知３０个标准Ｈ－血清中的１５个Ｈ－血清型，即Ｈ１、Ｈ２、Ｈ３、Ｈ４、Ｈ５、Ｈ６、Ｈ７、Ｈ８、Ｈ１３、Ｈ１４、Ｈ１５、Ｈ１６、Ｈ１７、Ｈ２２和Ｈ２６。其余的１９２株中，除１７５株为无鞭毛或自凝菌株无法进行血清学鉴定外，１６株（３．９％）的Ｈ－抗原不与已知２７个标准Ｈ－抗     

Nothomyrmecia macrops: A Living-Fossil Ant Rediscovered

The Australian Nothomyrmecia macrops is the most primitive living ant. Until recently rediscovered, it was known only from two 46-year-old specimens, both workers. All developmental stages and adult castes are now known. Adults have stridulatory organs placed ventrally, between abdominal sternites III (with plectrum) and IV (with stridulitrum), differing from all other Hymenoptera, where these organs are dorsal. The chromosome number is the highest recorded for Hymenoptera (2n = 92). Virgin queens are brachypterous. Other anatomical and behavioral features are reviewed. Most are primitive for ants, many being shared with Myrmecia, another primitive Australian genus. Fundamental differences in abdominal structure place Myrmecia near the base of the poneroid phylad of ant subfamilies, while Nothomyrmecia is a primitive formicoid.     

Detection of CN Emission from (2060) Chiron

In the past decade there has been a gradual, but substantial change in our understanding of the physical nature of (2060) Chiron. Once thought to be the first known member of a population of asteroids orbiting between Saturn and Uranus, Chiron is now generally regarded as the largest known comet. The detection of CN emission in the spectrum of Chiron is reported. Not only do these observations underscore the cometary nature of Chiron, but, at a heliocentric distance exceeding 11 astronomical units, represent the most distant detection yet of a neutral gas species common in comets. These results are consistent with the outgassing from Chiron being primarily driven by isolated outbursts of CO(2) from a very small fraction of Chiron's surface. These may be indicative of primordial inhomogeneities.     

Origin and evolution of outer solar system atmospheres

The atmospheres of bodies in the outer solar system are distinct in composition from those of the inner planets and provide a complementary set of clues to the origin of the solar system. This article reviews current understanding of the origin and evolution of these atmospheres on the basis of abundances of key molecular species. The systematic enrichment of methane and deuterated species from Jupiter to Neptune is consistent with formation models in which significant infall of icy and rocky planetesimals accompanies the formation of giant planets. The atmosphere of the Saturnian satellite Titan has been strongly modified by photochemistry and interaction with the surface over 4.5 billion years; the combined knowledge of this moon's bulk density and estimates of the composition of the surface and atmosphere provide some constraints on this body's formation. Neptune's satellite Triton is a poorly known object for which it is hoped that substantial information will be gleaned from the Voyager 2 encounter in August 1989. The mean density of the Pluto-Charon system is well known and suggests an origin in the rather water-poor solar nebula. The recent occultation of a star by Pluto provides evidence that carbon monoxide, in addition to methane, may be present in its atmosphere.     

Quantitation of RNA tumor viruses and viruslike particles in human milk by hybridization to polyadenylic acid sequences

RNA tumor viruses and viruslike particles from human milk are quantitated by hybridization of the polyadenylic acid regions in their 60S to 70S RNA to radioactive polyribouridylic acid of known specific activity. The length of the polyadenylic acid region in the 60S to 70S RNA of the human milk particle is identical to that of the known oncogenic RNA viruses.     

云南省植绥螨属一新种(蜱螨亚纲：植绥螨科)

 本文对采自云南省西双版纳地区的植绥螨属一新种——云南植绥螨Phytoseius yunnanensis sp.nov.进行详细描记,并附形态特征图。模式标本保存于沈阳农业大学植保系。     

Mesosiderite clasts with the most extreme positive europium anomalies among solar system rocks

Pigeonite-plagioclase gabbros that occur as clasts in mesosiderites (brecciated stony-iron meteorites) show extreme fractionations of the rare-earth elements (REEs) with larger positive europium anomalies than any previously known for igneous rocks from the Earth, moon, or meteorite parent bodies and greater depletions of light REEs relative to heavy REEs than known for comparable cumulate gabbros. The REE pattern for merrillite in one of these clasts is depleted in light REEs and has a large positive europium anomaly as a result of metamorphic equilibration with the silicates. The extreme REE ratios exhibited by the mesosiderite clasts demonstrate that multistage igneous processes must have occurred on some asteroids in the early solar system. Melting of the crust by large-scale impacts or electrical induction from an early T-Tauri-phase sun may be responsible for these processes.     

Homolanthionine excretion in homocystinuria

Patients with homocystinuria excrete in their urine small amounts of an amino acid indistinguishable from authentic L-homolanthionine. This compound could be formed from homocysteine and homoserine by a condensation analogous to that normally leading to cystathionine. The only other known occurrence of homolanthionine in nature is in a methionine-requiring mutant strain of Escherichia coli.