Overview of the Late Cretaceous Biota of the western São Paulo State,Brazil, Bauru Group     

Carlos Roberto A. Candeiro  Thomas Rich 《Journal of South American Earth Sciences》2010,29(2):346-353

The Turonian–Maastrichtian beds of the Bauru Group, western São Paulo State (Brazil), have yielded a diverse biota. The nine species of mesoecrocodilians are all mesosuchians. There is a single frog, a Neubatrachia. The vertebrates include, four types of fishes, a neobatrachian frog, an anilioid snake, two lizard, six species of podocnemid turtles, nine species of mesosuchian mesoecrocodilians three theropods, two birds, five titanosaurid sauropods, and one mammalian. The invertebrates include one cyclo, one cyclophoroid and eight pulmonates. Plants are represented by only two carophyte species. The biota from western São Paulo State is one the most diverse of the Late Cretaceous in Brazil. The biota from this area confirms that Bauru Group was connected to Patagonia and other Gondwanan areas during the Late Cretaceous.  相似文献   

On the diversity of diversity; is there still a poace for small area classification?     

Rich Harris 《Area》2001,33(3):329-336

  相似文献   

The M 4 Core Project with HST: I. Overview and first epoch     

L.R. Bedin  J. Anderson  D.C. Heggie  G. Piotto  A.P. Milone  M. Giersz  V. Nascimbeni  A. Bellini  R.M. Rich  M. van den Berg  D. Pooley  K. Brogaard  S. Ortolani  L. Malavolta  L. Ubeda  A.F. Marino 《Astronomische Nachrichten》2013,334(10):1062-1085

We present an overview of the ongoing Hubble Space Telescope large program GO‐12911. The program is focused on the core of M 4, the nearest Galactic globular cluster, and the observations are designed to constrain the number of binaries with massive companions (black holes, neutron stars, or white dwarfs) by measuring the “wobble” of the luminous (mainsequence) companion around the center of mass of the pair, with an astrometric precision of ∼50 µas. The high spatial resolution and stable medium‐band PSFs of WFC3/UVIS will make these measurements possible. In this work we describe (i) the motivation behind this study, (ii) our observing strategy, (iii) the many other investigations enabled by this unique data set, and which of those our team is conducting, and (iv) a preliminary reduction of the first‐epoch dataset collected on 2012 October 10. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora     

Barbara A. Emery  Ian G. Richardson  David S. Evans  Frederick J. Rich  Gordon R. Wilson 《Solar physics》2011,274(1-2):399-425

The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from 5 to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005?–?2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (～?1980, ～?1990, and ～?2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995?–?1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27-day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the >?2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods, showing that processes in the magnetosphere act as a low-pass filter between the solar wind and the radiation belt. The A _p/K _p magnetic currents observed at subauroral latitudes are sensitive to proton auroral precipitation, especially for 9-day and shorter periods, while the A _p/K _p currents are governed by electron auroral precipitation for 13.5- and 27-day periodicities.  相似文献   

An Upper Cretaceous (Campanian-Maastrichtian) actinopterygian fish assemblage from the marginal marine Adaffa Formation of Saudi Arabia     

Benjamin P. Kear  Thomas H. Rich  Mohammed A. Ali  Yahya A. Al-Mufarrih  Adel H. Matiri  Abdu M. Al-Masary  Yousry Attia 《Cretaceous Research》2009,30(5):1164-1168

Actinopterygian remains have been recovered from Upper Cretaceous (lower Campanian to lower Maastrichtian) marginal marine deposits of the Adaffa Formation in northwestern Saudi Arabia. The fossils comprise gars (Lepisosteidae), pachycormids (cf. Protosphyraena sp.), indeterminate pycnodontiforms, enchodontid teleosts (cf. Enchodus sp.) and other indeterminate Teleostei. This assemblage is significant because it includes a novel occurrence for the Middle East (Pachycormidae) together with taxa (Lepisosteidae, Pycnodontiformes, Enchodontidae) that have been previously recorded from Late Cretaceous faunas elsewhere in the Mediterranean Tethyan region.  相似文献   

Connecting the Distant Universe with the Local Fossil Record     

R. Michael Rich 《Astrophysics and Space Science》1999,265(1-4):453-460

This review considers implications regarding galaxy formationand evolution that can be drawn from study of the ages,abundances, and kinematics of stellar populations in the LocalUniverse. The wide abundance range in the Galactic bulge and in thehalo of M31 is consistent with chemical evolution in a starburstwith wind outflow. We question the notionthat the Galactic halo population is assembled fromdisrupted dwarf spheroidal galaxies, based on the presenceof metal rich stars in Local Group halos.The alpha-element enhancements of bulge giants are those expected from a system forming on a timescale of less than 1 Gyr. Direct measurement of the star formationhistory from turnoff photometry in Local Group galaxiesis not in complete agreement with the universal star formation rateinferred from high redshift studies. We argue that the properties of the Local Universe constrain galaxyformation theory just as strongly as the findings gleaned fromhigh redshift galaxies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

A distant magmatic source for Cretaceous karst bauxites of Southern Apennines (Italy), revealed through SHRIMP zircon age dating     

Maria Boni  Steven M. Reddy  Nicola Mondillo  Giuseppina Balassone  Rich Taylor 《地学学报》2012,24(4):326-332

  相似文献   

Modeling IR spectral energy distributions: a?pilot study of?starburst parameters and silicate absorption curves for some GOALS galaxies     

Michael A. Dopita  Lee Armus  Lisa J. Kewley  Jeff A. Rich  Dave Sanders  Phillip N. Appleton  Ben H. P. Chan  Vassilis Charmandaris  Aaron S. Evans  David T. Frayer  Justin H. Howell  Hanae Inami  Joseph A. Mazzarella  Andreea Petric  Sabrina Stierwalt  Jason Surace 《Astrophysics and Space Science》2011,333(1):225-239

This paper describes a pilot study into the spectral energy distribution (SED) fitting and the derivation of physical parameters for 19 galaxies observed as part of the Great Observatories All-sky LIRG Survey (GOALS) survey as observed with the Spitzer Space Telescope. For this we have used the pan-spectral fitting tools developed in a series of papers by Dopita and his co-workers. We show that the standard Lee and Draine ??astronomical silicate?? model cannot provide a good fit to the silicate absorption features as observed in the heavily dust-extinguished (A _V??50 mag.) starbursts. We have derived an empirical fit to the ??starburst silicate?? absorption in these objects. This absorption curve is consistent with the silicate grains being systematically larger in starburst environments than in the local Galactic interstellar medium. We demonstrate the sensitivity of the SED fitting to each of the fitted parameters, and derive these parameters for those galaxies which do not have an embedded AGN. This technique is simple and provides reasonably robust and uniform parameters for the starburst, especially as far as the star formation rate, population of old stars, compactness of the starburst region and total foreground extinction are concerned. However, the chemical abundances and the optical extinction cannot be reliably determined by this analysis, and optical SEDs will also be required to provide a complete characterization of the starburst region and of the surrounding galaxy.  相似文献   

Radiocarbon dates and the genesis of phytogenic near-shore sediments on St. Catherines Island,Georgia, USA     

Fredrick J. Rich  Lee Newsom  Brian Meyer  R. Kelly Vance 《Environmental Earth Sciences》2014,72(8):2985-2997

St. Catherines Island consists of a complex association of Pleistocene and Holocene sediments. The geographic location of the island at the center of Georgia Bight, a prominent re-entrant in the coastline of the southeastern USA, has resulted in the development of a very complex depositional and erosional history. For over 40,000 years the island has experienced a variety of physical, biological, and anthropological changes brought about by climatic, biotic, depositional, and anthropogenic events. Sedimentary deposits have been studied using diverse research tracks including palynology, dendrology, sedimentology, geophysics, and radiocarbon chronology, as well as archaeological techniques. This research focused on the interpretation of environments of deposition of strata that are exposed within the present surf zone, yet which bear the distinct signatures of upland/inland environments of deposition. Data derived from Late Pleistocene and Holocene accumulations of peat and mollusc- and wood-bearing muddy strata of certain on-shore and near-shore origins reveal diverse events relating to shoreline dynamics, plant community changes, and net shoreward migration of this island during the Late Holocene.  相似文献   

New high‐resolution age data from the Ediacaran–Cambrian boundary indicate rapid,ecologically driven onset of the Cambrian explosion     

Ulf Linnemann  Maria Ovtcharova  Urs Schaltegger  Andreas Grtner  Michael Hautmann  Gerd Geyer  Patricia Vickers‐Rich  Tom Rich  Birgit Plessen  Mandy Hofmann  Johannes Zieger  Rita Krause  Les Kriesfeld  Jeff Smith 《地学学报》2019,31(1):49-58

The replacement of the late Precambrian Ediacaran biota by morphologically disparate animals at the beginning of the Phanerozoic was a key event in the history of life on Earth, the mechanisms and the time‐scales of which are not entirely understood. A composite section in Namibia providing biostratigraphic and chemostratigraphic data bracketed by radiometric dating constrains the Ediacaran–Cambrian boundary to 538.6–538.8 Ma, more than 2 Ma younger than previously assumed. The U–Pb‐CA‐ID TIMS zircon ages demonstrate an ultrashort time frame for the LAD of the Ediacaran biota to the FAD of a complex, burrowing Phanerozoic biota represented by trace fossils to a 410 ka time window of 538.99 ± 0.21 Ma to 538.58 ± 0.19 Ma. The extremely short duration of the faunal transition from Ediacaran to Cambrian biota within less than 410 ka supports models of ecological cascades that followed the evolutionary breakthrough of increased mobility at the beginning of the Phanerozoic.  相似文献