Erinaceinae and Brachyericinae

116 p. : ill., maps ; 26 cm.Thesis (Ph. D.)--Columbia University.Includes bibliographical references (p. [111]-116)."Modern Erinaceidae include the familiar hedgehog, Erinaceus europaeus, the archetypical primitive placental mammal in the minds of many biologists. Now restricted to the Old World, the family flourished in North America during the Miocene when three subfamilies were present there. Restricted to North America, the Brachyericinae seem to have originated on that continent. Both North American genera of Amphechinini (new tribe of the Erinaceinae) are well known in the Old World in earlier Oligocene deposits and hence appear to have immigrated into North America just before their first appearance there in the early Miocene. Area of origin of the Erinaceini may be interpreted as (1) unspecified within Holarctica plus the Ethiopian Region or (2) as external to Holarctica, depending on how the evidence is weighed. The sudden appearance of the tribe over the extent of Holarctica plus the Ethiopian Region at the beginning of the Miocene and the existence of an adequate structural ancestor in North America immediately prior to the time of initial appearance suggests the first interpretation. Counter to this, the presence in the Oligocene of a derived sister group of the Erinaceini (i.e., the Amphechinini) suggests that the tribe existed by that time, probably in an area where adequate collections from that epoch have not been made, e.g., Africa. Van Couvering (1972) has suggested that many forms which suddenly appear in the Miocene record of Europe without known precursors may have existed in Africa during the Oligocene and migrated only after the two continental blocks met in the mid-Cenozoic. Because the African Oligocene record of small mammals is so pitifully poor and a plausible reason exists for expecting that the Erinaceini existed there during that epoch, the second hypothesis appears more probable at this time. Once established in North America in the early Miocene, both the Erinaceinae and Brachyericinae had relatively uneventful histories. Least eventful was that of the Amphechinini, one species (Parvericius montanus) appearing to be conspecific with forms known in the Oligocene of Asia and the other species (Amphechinus horncloudi) differing only slightly from its Old World predecessors and contemporaries in that genus. Although A. horncloudi did not survive the Arikareean when it first appeared, P. montanus persisted with little noticeable change from that age through the Barstovian. Only one species of Erinaceini is recognized, Untermannerix copiosus (new), which appeared in the Barstovian and persisted until the Clarendonian with no noticeable change. More complex was the history of the Brachyericinae. Both genera have two species of markedly different size. In each, the smaller species appears to suddenly replace the larger. In the case of Metechinus, the evidence for this abruptness is equivocal but for Brachyerix it is highly compelling. Most useful in the analysis of the data has been the cladistic method as outlined by Hennig in his 1966 work. It was a fundamental tool in the development of the more plausible second hypothesis of the history of the Erinaceini outlined above. Determination of primitive and derived states or polarity of a given character, a fundamental problem of the cladistic method, was made by analyzing the distribution of the different states among the several groups recognized in an initial, credible higher phylogenetic hypothesis. Character states widely scattered in a haphazard pattern among the groups were regarded as primitive; ones found in only a few groups, particularly when thought to be closely related, were regarded as derived. In cases where the pattern was ambiguous, by restricting the sample examined to forms known prior to an arbitrary geologic epoch, it was often possible to determine polarity in this subset. Because in this procedure one is examining the forms that would have been available had one lived at that earlier, arbitrary date, the methodological pitfalls are no different from examining the total sample including modern forms"--P. 5

Description of the tympanic regions of Paraechinus and Podogymnura

58 p. : ill. ; 24 cm.Includes bibliographical references (p. 56-58)."Although living hedgehogs have long been regarded [as] the archetypes of the primitive placental mammal, they have nonetheless had a complex Cenozoic history that is reflected in the recognition of three extinct and two living erinaceid subfamilies. Members of one extinct subfamily, the Brachyericinae, underwent a remarkable shortening of the skull and a reduction in the number of teeth during the Oligocene, Miocene, and early Pliocene. This trend culminated in the two North American genera, Brachyerix and Metechinus, in which only three teeth were retained anterior to P[subscript]4. Dimylechinus, a European form from the early Miocene, and Exallerix from the medial Oligocene of Asia both retained at least four teeth anterior to P[subscript]4. None of the four genera had an M[subscript]3. Brachyerix and Metechinus occur from the Great Plains to the Pacific coast of North America. Brachyerix is temporally restricted to the Miocene; Metechinus occurs in late Miocene and early Pliocene sediments. Although both genera are known from several localities, they are never found together, which may reflect an ecological separation of these two forms during temporal overlap. Both are known only from cranial osteology. During the past 40 years, the differences between these two North American genera have not been well defined, and only now with the availability of several specimens of each can the generic boundaries be adequately reviewed. Two species of Brachyerix are recognized in the present paper. Brachyerix macrotis, restricted to the early and medial Miocene, is the larger of the two and differs from B. incertis, new combination (late Miocene), in having a stronger lingual cingulum on P[superscript]3 and in entirely lacking a P[superscript]3 protocone. Metechinus marslandensis can now be synonymized with B. macrotis, whereas Talpa incerta and Metechinus fergusoni are both junior synonyms of B. incertis. Only Metechinus nevadensis still requires generic separation owing to its unique basicranium, small auditory bullae, nature of the sagittal crest, and relatively anteroposteriorly compressed M[subscript]1 trigonid. Dimylechinus bernoullii is an adequate structural ancestor for Brachyerix macrotis and its descendents. However, as both Dimylechinus and Exallerix are known only from single specimens, their relationship to the North American brachyericines as well as to one another is not well understood and will not be until further specimens are found. An appendix describing the ear regions of two living hedgehog genera, Paraechinus and Podogymnura, is included to supplement Butler's (1948) paper on the erinaceid ear region. Paraechinus is the only living erinaceid that has bony tubes covering part of the blood vessels contained in the tympanic cavity, a condition developed to the extreme in the Miocene Brachyerix"--P. [1]-2

Observations of Lick Standard Stars Using the SCORPIO Multi-Slit Unit at the SAO 6-m Telescope

We present Lick line-index measurements of standard stars from the list of Worthey. The spectra were taken with the multi-slit unit of the SCORPIO spectrograph at the 6-m Special Astrophysical observatory telescope. We describe in detail our method of analysis and explain the importance of using the Lick index system for studying extragalactic globular clusters. Our results show that the calibration of our instrumental system to the standard Lick system can be performed with high confidence.Comment: 12 pages, 3 figure

New eucryptodiran turtle

35 p. : ill., maps ; 26 cm.Includes bibliographical references (p. 28-30).Chubutemys copelloi is the oldest nonmarine cryptodire from South America represented by a skull. The skull and associated postcranial fragments are from the Aptian Cerro CostaŠno Member of the Cerro Barcino Formation of Chubut, Argentina. Chubutemys has a processus trochlearis oticum, showing that it is a cryptodire, and an enclosed canalis caroticus internus extending to the posterior margin of the pterygoid, showing that it is a eucryptodire. The skull of Chubutemys is similar to that of other primitive eucryptodires, particularly Dracochelys, but also to Hangaiemys, Judithemys, Sinemys, and Ordosemys. Chubutemys differs from all these, however, in possessing a solidly roofed skull, formed by long, wide parietals, rather than a posterior emargination. Chubutemys also differs from these taxa in having no cheek emargination. A phylogenetic analysis using PAUP* analyzed 104 parsimony-informative characters resolving into one most parsimonious cladogram of 224 steps, a consistency index of 0.55, and a retention index of 0.74. The phylogenetic analysis weakly joins Chubutemys and meiolaniids on the basis of the prefrontal-postorbital contact. Chubutemys also has a fully roofed skull and slitlike posterior opening of the foramen caroticum laterale (foramen posterius canalis caroticus laterale), features to be expected in a meiolaniid sister taxon. Chubutemys provides further evidence that meiolaniids are related to 'basal' eucryptodires ('sinemydids/macrobaenids'), that is, eucryptodires outside the living Cryptodira, the Polycryptodira. The basicranial morphology of meiolaniids, with an intrapterygoid slit, rather than being a unique feature of the group is instead a modified state of the primitive eucryptodire condition, as seen in such forms as Chubutemys, Dracochelys, Ordosemys, and Sinemys. The intrapterygoid slit of meiolaniids is homologous with the pterygoid flange associated with the foramen caroticum laterale (foramen posterius canalis caroticus laterale of Sukhanov) in non-Polycryptodiran eucryptodires like Ordosemys. Chubutemys shows that nonmarine eucryptodires were present in South America in the Cretaceous, as they were in North America, central Asia, and Australia

Accessing bacterial dark matter for improved enzyme discovery and engineering

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Spectroscopic Observations and Analysis of the Unusual Type Ia SN 1999ac

We present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. Prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger SiII and CaII signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from SiII are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v_10, R(SiII), dv(SiII)/dt, and d_m15 further underlines the unique characteristics of SN 1999ac. We find convincing evidence of CII 6580 in the day -15 spectrum with ejection velocity v > 16,000 km/s, but this signature disappears by day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.Comment: 40 pages, 24 figures, accepted for publication in The Astronomical Journa

Measurement of the t-channel single top quark production cross section

The D0 collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb^-1 of ppbar collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14 +0.94 -0.80 pb for the t-channel and 1.05 +-0.81 pb for the s-channel. The measured t-channel result is found to have a significance of 4.8 standard deviations and is consistent with the standard model prediction.Comment: 7 pages, 6 figure

Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at sqrt{s}=1.96 TeV

We present cross section measurements for Z/gamma*+jets+X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron proton anti-proton collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb-1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.Comment: Published in PLB. 11 pages, 3 figure

Measurement of the W boson mass

We present a measurement of the W boson mass in W -> ev decays using 1 fb^-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W -> ev candidate events, we measure M_W = 80.401 +- 0.043 GeV. This is the most precise measurement from a single experiment.Comment: As published in PR

Measurement of the B0_s semileptonic branching ratio to an orbitally excited D_s** state, Br(B0_s -> Ds1(2536) mu nu)

In a data sample of approximately 1.3 fb-1 collected with the D0 detector between 2002 and 2006, the orbitally excited charm state D_s1(2536) has been observed with a measured mass of 2535.7 +/- 0.6 (stat) +/- 0.5 (syst) MeV via the decay mode B0_s -> D_s1(2536) mu nu X. A first measurement is made of the branching ratio product Br(b(bar) -> D_s1(2536) mu nu X).Br(D_s1(2536)->D* K0_S). Assuming that D_s1(2536) production in semileptonic decay is entirely from B0_s, an extraction of the semileptonic branching ratio Br(B0_s -> D_s1(2536) mu nu X) is made.Comment: 7 pages, 2 figures, LaTeX, version with minor changes as accepted by Phys. Rev. Let