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1、1.FossilFeathers--NotJustFortheBirdsAtroveoffossilsshedslightontheevolutionoffeathers.THEfossilrecordis,famously,fullofholes.Onesuchlacunahasbeentheabsenceofwell-preservedfeathersfromtheCretaceous—theperiodbetween145mand65myearsagothatendedwiththemassextinctionthatwi
2、pedoutthedinosaurs.Now,thisgaphasbeenpartlyfilled.Inthisweek’sScience,ateamledbyRyanMcKellarfromtheUniversityofAlbertareportthediscoveryofelevenfeatherspreservedinamberfromthelatterpartoftheCretaceous,about70m-85myearsago.Intriguingly,notallofthemseemtocomefrombirds.
3、Theoriginoffeathersisamystery.Theearliestknownbird,Archaeopteryx,livedduringtheJurassic,theperiodbeforetheCretaceous.ButfossilsfromChinasuggesttheprecursorsoffeathers—simple,filament-likestructurespossiblyusedforinsulation—evolvedinlandlubbingdinosaursandwereonlylate
4、radaptedforflight.ThetoppictureshowssimilarfilamentsdiscoveredbyDrMcKellarandhisteam,suggestingflightlessdinosaurssportingsuchprotofeatherswerestillaroundinthelateCretaceous.NotallthefeathersfoundbyDrMcKellarweresoprimitive,though.Thesecondpictureshowsonesimilarinsha
5、petothosesportedbymodernbirds.Modernfeathersconsistofthousandsoffibresheldtogetherbytinyhooks.Thedetailsofthatdesigncanbetweakedtochangeafeather’scharacteristics,offeringwaterproofing,insulation,streamliningandsoon.Thethirdpictureshowsfeathersthathavejustsuchaspecial
6、ization:coilingreminiscentofthatseeninthefeathersofmoderndivers.Suchcoilingallowsafeathertoabsorbwater,whichstreamlinesandinsulatestheowner.Thesefeathers,then,presumablyadornedadivingbird—perhapsHesperornis,aflightlessNorthAmericandiverfrompreciselythisperiod.Thefina
7、lpictureshowspigmentationpreservedinafossilfeather.Differentfeathershavedifferentpatternsofcolor,suggestingthatCretaceousdinosaurs—flyingorotherwise—usedtheirfeathersfordisplay.CharlesDarwinoncesaidthatcontemplatingapeacock’stailmadehimsick,suchwasthedifficultyofexpl
8、ainingitscomplexity.DrMcKellar’sfindssuggest,atleast,thatthatcomplexitybegantoevolvealongtimeago.2.HumanEvolution--YouLookFamiliarA
