@article{JewittWeaverMutchleretal.2011, author = {Jewitt, David and Weaver, Harold and Mutchler, Max and Larson, Stephen and Agarwal, Jessica}, title = {Hubble space telescope observations of main-belt comet (596) scheila}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters}, volume = {733}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {2041-8205}, doi = {10.1088/2041-8205/733/1/L4}, pages = {5}, year = {2011}, abstract = {We present Hubble Space Telescope Observations of (596) Scheila during its recent dust outburst. The nucleus remained point-like with absolute magnitude H(V) = 8.85 +/- 0.02 in our data, equal to the pre-outburst value, with no secondary fragments of diameter >= 100m (for assumed albedos 0.04). We find a coma having a peak scattering cross section similar to 2.2x10(4) km(2), corresponding to a mass in micron-sized particles of similar to 4x10(7) kg. The particles are deflected by solar radiation pressure on projected spatial scales similar to 2x10(4) km, in the sunward direction, and swept from the vicinity of the nucleus on timescales of weeks. The coma fades by similar to 30\% between observations on UT 2010 December 27 and 2011 January 4. The observed mass loss is inconsistent with an origin either by rotational instability of the nucleus or by electrostatic ejection of regolith charged by sunlight. Dust ejection could be caused by the sudden but unexplained exposure of buried ice. However, the data are most simply explained by the impact, at similar to 5 km s(-1), of a previously unknown asteroid similar to 35m in diameter.}, language = {en} } @article{BarnettWestburySandovalVelascoetal.2020, author = {Barnett, Ross and Westbury, Michael V. and Sandoval-Velasco, Marcela and Vieira, Filipe Garrett and Jeon, Sungwon and Zazula, Grant and Martin, Michael D. and Ho, Simon Y. W. and Mather, Niklas and Gopalakrishnan, Shyam and Ramos-Madrigal, Jazmin and de Manuel, Marc and Zepeda-Mendoza, M. Lisandra and Antunes, Agostinho and Baez, Aldo Carmona and De Cahsan, Binia and Larson, Greger and O'Brien, Stephen J. and Eizirik, Eduardo and Johnson, Warren E. and Koepfli, Klaus-Peter and Wilting, Andreas and Fickel, J{\"o}rns and Dalen, Love and Lorenzen, Eline D. and Marques-Bonet, Tomas and Hansen, Anders J. and Zhang, Guojie and Bhak, Jong and Yamaguchi, Nobuyuki and Gilbert, M. Thomas P.}, title = {Genomic adaptations and evolutionary history of the extinct scimitar-toothed cat}, series = {Current biology}, volume = {30}, journal = {Current biology}, number = {24}, publisher = {Cell Press}, address = {Cambridge}, issn = {0960-9822}, doi = {10.1016/j.cub.2020.09.051}, pages = {14}, year = {2020}, abstract = {Homotherium was a genus of large-bodied scimitar-toothed cats, morphologically distinct from any extant felid species, that went extinct at the end of the Pleistocene [1-4]. They possessed large, saber-form serrated canine teeth, powerful forelimbs, a sloping back, and an enlarged optic bulb, all of which were key characteristics for predation on Pleistocene megafauna [5]. Previous mitochondrial DNA phylogenies suggested that it was a highly divergent sister lineage to all extant cat species [6-8]. However, mitochondrial phylogenies can be misled by hybridization [9], incomplete lineage sorting (ILS), or sex-biased dispersal patterns [10], which might be especially relevant for Homotherium since widespread mito-nuclear discrepancies have been uncovered in modern cats [10]. To examine the evolutionary history of Homotherium, we generated a -7x nuclear genome and a similar to 38x exome from H. latidens using shotgun and target-capture sequencing approaches. Phylogenetic analyses reveal Homotherium as highly divergent (similar to 22.5 Ma) from living cat species, with no detectable signs of gene flow. Comparative genomic analyses found signatures of positive selection in several genes, including those involved in vision, cognitive function, and energy consumption, putatively consistent with diurnal activity, well-developed social behavior, and cursorial hunting [5]. Finally, we uncover relatively high levels of genetic diversity, suggesting that Homotherium may have been more abundant than the limited fossil record suggests [3, 4, 11-14]. Our findings complement and extend previous inferences from both the fossil record and initial molecular studies, enhancing our understanding of the evolution and ecology of this remarkable lineage.}, language = {en} }