2023年12月2日发(作者：称赞的近义词是什么)
第43卷 第2期古脊椎动物学报 pp.85～99 figs.1～52005年4月VERTEBRATAPALASIATICA蒙古新发现的渐新世山河狸和松鼠类化石1)王伴月1 D.达什泽维格2(1中国科学院古脊椎动物与古人类研究所 北京 100044)(2蒙古科学院古生物中心 乌兰巴托)摘要:蒙古中部地区的三达河组(HsandaGolFormation)是亚洲渐新世陆相地层的经典地层之一。三达河组的沉积岩层现被分成两个岩性段:上部早渐新世晚期-?晚渐新世山地段(ShandMember)和下部早渐新世早期塔塔尔段(TatalMember);两岩段间有时夹有KharKhoroo玄武岩层(BryantandMcKenna,1995;MengandMcKenna,1998)。该玄武岩层的时代用40Ar/39Ar法被确定为距今31.5Ma(Hcketal.,1999,他们称其为BasaltI)。三达河组中产有丰富的哺乳动物化石,特别是啮齿类化石(MatthewandGranger,1923;Kowalski,1974;RusllandZhai,1987;Hcketal.,1999)。近年来,本文的后一作者在三达河组中又采集到一批啮齿类化石,其中包括松鼠和山河狸2科的化石。本文是对这两类化石新材料的记述。现生的松鼠科分异很大,而且大多数都分布在亚洲。然而,松鼠科化石在古近纪时在北美和欧洲却很丰富。在北美出现于晚始新世,在渐新世时已明显分异;在欧洲出现于早渐新世,在中新世时分异很大。相反,亚洲古近纪的松鼠化石却发现得很少,标本也很破碎。已报道的只有3件标本。2件产自党河下游地区:Bohlin(1946)报道的晚渐新世的Sciurussp.,标本只是2枚单个臼齿(M3和m2);王伴月、邱占祥(2004)报道的早渐新世的党河鲜松鼠(Oligosciurusdangheensis),标本只是一段带m1～2的下颌骨。还有一件是Minjin(2004)报道的蒙古渐新世的三达河克热姆鼠(Kheremhsandgoliensis),标本也只是一段带m1～3的下颌骨。本文报道的松鼠化石产自蒙古国的巴彦洪戈尔省的塔石盖贝(TashgainBel)地点的三达河组上部山地段,时代为早渐新世晚期-?晚渐新世。这批松鼠化石标本包括1件具P3～M3的上颌骨(PC3629)和2段下颌骨(PC36210和PC36211)。这是亚洲古近纪目前已知的最好的一批松鼠化石标本,代表松鼠科Kherem属的一新种:亚洲克热姆鼠(.)。其主要特征是颊齿较大,较宽;下内尖的高度和下次尖的大小从m1到m3变化不大,彼此相近;下内脊较明显;下内尖较明显,与下后边脊间有浅沟分开等。ca的形态特征表明,Kherem属应归入北美的Cedromurinae亚科。新的发现表明,亚洲渐新世的松鼠已发生了分异,至少可分为3支。以Kherem为代表的一支,与北美早期的cedromurines有较近的系统关系。它可能是由类似于北美Oligospermophilus的种类演化并迁徙到亚洲来的。现生的山河狸只有一种(Aplodontiarufa),仅生活在北美西部沿海地区。但从始新世到中新世,山河狸却遍布全北区。它们在北美较繁盛,分异大,但在亚洲发现得很少。在亚洲渐新世地层中虽曾报道过3属4种山河狸化石,但材料都很少(Prosciurusordosicus和P.?shantun2gensis均只有一枚单个的牙)。山河狸化石在蒙古渐新世地层的新发现表明,亚洲渐新世的山河狸化石比已知的要丰富。1)国家自然科学基金重点项目(编号:40232023)资助。收稿日期:2004-08-1886古 脊 椎 动 物 学 报 43卷 本文描述的山河狸化石分别采自蒙古南戈壁省Shunkt地点的山地段和前杭爱省UlaanKhongil(=TatalGol)地点的塔塔尔段。它们代表原松鼠属的3类:蒙古原松鼠(新种)(.)、蒙古原松鼠(相似种)(iensis)和小原松鼠(新种)(.)。蒙古原松鼠的主要特征是下颊齿的下中附尖与下后附尖脊连,下中尖发育较弱,下外中脊弱或无;p4无下前边尖和下前齿带;m1具从下外脊伸向下次脊的小刺;m2和m3的下后脊II较发育;下次脊在p4和m1后弯,与下后边脊连,在m2和m3横向,伸达下外脊等。蒙古原松鼠(相似种)与蒙古原松鼠的区别是:颊齿尺寸较小,p4具明显的下外中脊,p4和m1的下次脊弯曲度较缓,m1缺从下外脊伸向下次脊的小刺,m2～3的下后脊II较短等。小原松鼠的主要特征是:个体较小;齿冠较低;下臼齿的下中附尖孤立;下颊齿的下次脊横向、较低,与下外脊连,下中尖和下外中脊均较明显,下次尖明显向前颊侧延伸,具明显的齿带等。蒙古渐新世啮齿类化石的新发现表明,亚洲渐新世的松鼠和山河狸与北美的关系要比与欧洲的近。关键词:蒙古,渐新世,松鼠科,山河狸科中图法分类号:Q915.873 文献标识码:A 文章编号:1000-3118(2005)02-0085-15NEWOLIGOCENESCIURIDSANDAPLODONTIDS(RODENTIA,MAMMALIA)FROMMONGOLIAWANGBan2Yue1 DemberelyinDASHZEVEG2(1InstituteofVertebratePaleontologyandPaleoanthropology,ChineAcademyofSciencesBeijing100044)(2PaleontologicalCenter,MongolianAcademyofSciencesUlaanbaatar)Abstract AnewspeciesofKherem,ca,andthreenewformsofProsciurus(.,.)asiatica,knownfromShandMember(lateearlyOligocene2?lateOligocene)ofMongolia,ischaracterizedby:oliensis;m1～3withsubequallyhighmetaconidandlargehypoconid,withmoredistincteegenerasofardescribedfromAsia(Sciurus,OligosciurusandKherem)mayreprentthreedifferentlineages,urusmongoliensisisknownfromShandandTatalMembersoftheHsandaGolFormation,Oligocene,nfeaturesare:brachydontcheekteethhavemesostylidconnectedwithmetastylidcrest,weakmesoconid,andweakornoectomesolophid;anteroconidandanteriorcingulumareabntonp4;anaccessorycrestextendsfromectolophidtohypolophidonm1;metalophidIIiswelldevelopedonm2～3;hypolophidbendsposteriorlytojoinwithposterolophidonp4～m1,butstraighttojoinwithectolophidonm2～iensisinhavingsmallercheekteethinsize,p4havingdistinctectomesolophid,p4andm1havinggentlycurvedhypolophid,m1lackingaccessorycrestfromectolophidtohypolophid,andm2～uruspisinnus,collectedfromTatalMember,alophidIIisshort,andthehypolophidistransver,low,oconidandectomesolophidarewelldeveloped,materialoftheMongolianAplodontidaenotonlyhasconfirmedtheearlyexistenceofProsciurusinAsia,butalsoshowsthatProsciuruxperiencedconsiderablediversityduringtheOligoceneinAsia.2期 王伴月等:蒙古新发现的渐新世山河狸和松鼠类化石87BoththesciuridsandaplodontidsfoundfromOligoceneofAds Mongolia,Oligocene,Sciuridae,Aplodontidae1 IntrodgoceneHsandaGolFormationinCentralMongoliaisoneoftheclassicstratabearingrichmammalianfossilsinAsia(MatthewandGranger,1923;Kowalski,1974;RusllandZhai,1987;Hcketal.,1999).Recentlyithasbeensubdividedintothreeparts(fromtoptobottom):lateearlyOligocene2?lateOligoceneShandMember,KharKhorooLava,andearlyearlyOligoceneTatalMember(BryantandMcKenna,1995;MengandMcKenna,1998).Hcketal.(1999)reporteda40Ar/39ArdateoftheKharKhoroolava(=theirBasaltI)ntyearsthelatterauthoroftheprentpapercollectedsomenewrodentspecimensfromtheHsandaGolFormationinCentralMongolia(Fig.1).ThenewmaterialoftheSciuridaeandAplodontidaearedescribedinthispaper.)andaplodontid(△)fossilsFig.1 MapofMongoliashowingthelocalitiesbearingthesciurid(○inBel;hongil;Theextantsciuridsareabundantandwidelydiversified,ogene,however,theywereratherdiversifiedonlyinNorthAmericaandEurope,agmentteOligoceneandOligosciurusdangheensisfromearlyOligoceneinDangheareaofGansu,China(Bohlin,1946;WangandQiu,2004),andKheremhsandgoliensisfromOligoceneinMongolia(Minjin,2004).Thesciuridspecimensdescribedhereincludeoneupperjawandtwomandibles,findnotonlyindicatesthatthesciuridswerealreadysomewhatdiversifiedduringOligoceneinAsia,butalsothroantAplodontidaeisrer,theirfossilswerlytothesciurids,theywereconsiderablydiversifiedduringOligoceneinNorthAmerica,wfivespeciesoffourgenera(Plesispermophilussp.,Haplomysarboraptus,Promeniscomyssinensis,Prosciurusordosicus,and88古 脊 椎 动 物 学 报 43卷P.?shantungensis)havebeenreportedfromOligoceneinAsia(Argyropulo,1939;RensbergerandLi,1986;Wang,1987).,bothProsciurusordosicusandP.?shantungensisarereprentedbyasingleisolatedtooth).ThenewspecimensfromMongoliareprentthreenewtaxaoftheAplodontidae,indicatingthatduringtheOligminologyforsciuridsudherefollowsQiu(1996),andthatforaplodontidsfollowsWang(1987).Abbreviation:MAE,ThejointMongolianAcademyofSciencesandAmericanMuumofNaturalHistoryPaleontologicalExpedition;PC,PaleontologicalCenterofMongolianAcademyofSciences;SG,ShandGol.2 SystmaticsSciuridaeFischerdeWaldheim,1817 CedromurinaeKorthetEmry,1991 KheremMinjin,2004 Typespecies KheremhsandgoliensisMinjin,edspecies ddiagnosis eethbrachydont;P4～M2withincompleteectoloph,singlebutwell2developedmetaconulejoiningwithposteroloph,withoutdistincthypocone;lowercheekteethwithsmalltrigonidbasin,rathernarrowmesostylid,poorlydevelopedmesoconid,.(Fig.2;Table1) Holotype Apartialleftmandibularramuswithi2,p4～m3(PC36210).Paratype AfragmentaryleftupperjawwithP3～M3(PC3629).Referredspecimen Apartialleftmandibularramuswithi2,p4～m2(PC36211).Localityandhorizon TashgainBel(45°27′47″N,101°12′11″E),Bayanhongor,Mongolia;LateearlyOligocene2?sis oliensis;m1～3withsubequallyhighmetaconidandlargehypoconid,moredistinctentolophid,ogy Asiatica,Latin,ption Theanteriorteriorpalatefstemabetweeni2andp4isshorterthandformulais1023/nc4istransverlywidetrapezoidinocclusalview,withthebuccalborderlongerthanthe2期 王伴月等:蒙古新发现的渐新世山河狸和松鼠类化石eriorandposteriorarmsotinctmesostyleisparatedbyashallowgrooveintotwocusps:erolophisdevelopedonthebuccalpartoftheanteriormarginofthe4hasthreeroots,1iheprominentfeaturesinM1isthatthewell2d2isslightlylargerthantheM1insize,3istriangularinocclusalview,mesostylesaredistinct,cusp(=hypocone?)insurroundedbytheprotoloph,mesostyle,ss2ctionisoval,witmelcoverstheanteriorsideandabouthalfofthelateralside,4istrapezoidinocclusalview,rowandyanteroconidstandsontheanterolingualsideoftheprotoconid,andispoconidissubequaltotheprotoconidinsize,locateterolophidiscontinuouswiththehypoconid,tinctmesostylidisparatedfaight,shortectolophidislocatedone2thirdbuccally,1isrhomboidinocclusalview,gonidisshortanteroposteriorly,eanterolophidandmetalophidarecomplete,alophidiscompleteontheholotype(PC36210),gonidofm3issimilartothatofm2,butitstalonidislarger,witharoundedposterior90古 脊 椎 动 物 学 报 43卷Fig.2 alviewofapartialleftupperjawwithP3～M3(PC3629,paratype);alviewofapartiallefthorizontalramuswithi2,p4～m2(PC36211);allefthorizontalramuswithi2,p4～m3(PC36210,holotype),alview;lview2期 王伴月等:蒙古新发现的渐新世山河狸和松鼠类化石oconulidpartisbroken,3hasalsofourroots:twoanterior,onelargeposterior,ions 1 .(mm)oliensisP3～M3LP4～M3LM1～3LP3LP3WP4LP4WM1LM1WM2LM2WM3LM3WPC3629(Paratype)9.48.96.811.32.232.23.12.33.12.72.9p4～m3Lm1～3Lp4Lp4TrW(TaW)p4TrW/L(TaW/L)m1Lm1TrW(TaW)m1TrW/L(TaW/L)m2Lm2TrW(TaW)m2TrW/L(TaW/L)m3Lm3TrW(TaW)m3TrW/L(TaW/L)i2L(a2p)i2Wi2W/LPC36210(Holotype)9.27.22.41.8(2.1)0.75(0.88)2.12.3(2.4)1.1(1.14)2.52.4(2.5)0.96(1)32.4(2.1)0.8(0.7)2.61.60.62PC36211MAE2SG29722110(Holotype)6.4532.11.8(2.2)0.86(1.05)2.12.4(2.5)1.14(1.19)2.32.7(2.8)1.17(1.22)1.8531.693(1.963)0.9133(1.0633)2.131.893(2.13)0.933(133)2.531.83(1.63)0.7233(0.6433)2.81.70.610.653 Abbreviations:;L(a2p).lengthfromanteriorsidetoposteriorside;;ftrigonid;ftalonid.3AfterMinjin(2004);33CalculatedbadonthemeasurementsofMinjin(2004).Comparisonanddiscussion Themajorfeaturesofthenewspecimens(thepositionoftheanteriorborderofmastericfossa,thecrown2heightofthecheekteeth,thepatternoftheentolophidandectolophidinthelowermolars,theabnceofdistinctmesoconid,andtheprenceofcompletemetalophidⅡinm1)areidenticalwiththoofKheremhsandgoliensisdescribedbyMinjin(2004)fromthesamelocality,r,oliensisinthefollowingpoints:thelowermolarsareabout10%oliensis(eTable1);theheightoftoliensis;them1hasadistincthypoconulid;theentolophidismoredistinctinthemolars,andtheentoconidismoredunately,oliensisisbadonasinglelowerjaw,andthefiguresgivenbyMinjin(2004)tknowwntheabovelisteddifferences,withsomerervations,wetentativelypropoanewspeciesforthenewspecimens,hephylogeneticpositionofKheremintheSciuridae,Minjin(2004)mentioned:“TheplacementofKheremwithinSciuridaeisquiteambiguous.”Now,caheknownsciurids,arethefollowingfeaturesincommon:theanteriorborderofmastericfossaislocatedbelowtheposteriorpartofm1;theuppercheekteethhaveanectoloph,aminuteprotoconule,andametalophweaklyconnectingwiththeprotocone;thelowercheekteethhavea92古 脊 椎 动 物 学 报 43卷clonceofanectolophinuppermolarshasbeenconsideredsynapomorphousofthecedromurines(KorthandEmry,1991).Kherempossssuchafeature,romurinaehavebeensofarknowntoincludeonlytwogeneraofNorthAmerica:Cedromus(earlyOligocene)andOligospermophilus(fromlateEocenethroughearlyOligocene)(KorthandEmry,1991).KheremisdifferentfromCedromusinsuchfeaturesas:theectolophisincomplete;themetaconuleiswelldevelopedjoiningwithposteroloph;theentolophidbendsbackwarghKheremissimilartoOligospermophilusinhavingincompleteectolophonuppercheekteethandashallowgroovebetweenentoconidandposterolophid,theformerdiffersfromthelatterinhavinghighercrownedcheekteeth;uppermolarshavinglargermetaconulejoiningtheposteroloph,butlackinghypocone;sawhole,ntheevolutionarytendenciesofthesciuridssuggestedbyKorth(1994,p.116),probablyevolvedfromsomeOligospermophilus2likeformbyincreasingitstoothcrownheight,reducingthehypocone,provestenable,KheremmicathedistributionoftheCedromurinaewouldnotbelimitedtoNorthAmerica,herelationshipbetweenCedromusandKherem,omustheectolophiscompleteandthemesostylidextendstransverly,wthreegeneraofsciurids(Sciurus,OligosciurusandKherem)differsfromOligosciurusinbeinglargerinsize,moreanteriorlylocatedmastericfossaandmentalforamen,havinghighercrownedcheekteeth,ben2bulukisalsodifferentfromKherem,beingsmallerinsize,lowerincheektoothcrown,ben2bulukemstobemoreadvancedthanKherem,veryoneofthethreeAsiantaxahasitsownautapomorphicfeatures(Oligosciurushasmoreanterobuccallyextendinghypoconid;ntolophid;Kheremislargerinsize,cheekteethhighercrowned,uppercheekteethwithectolophandwell2developedmetaconulejoiningwithposterolophetc.),,inturn,indicatesthantidaeBrandt,1855 ProsciurinaeWilson,1949 ProsciurusMatthew,1903 .(Fig.3;Table2) Holotype Agmentofleftmandibularramuswithposteriorpartofi2andp4～m3(PC29253).Localityandhorizonofholotype Shunkt,;mngovǐ,Mongolia;lateearlyOligocene2?edspecimens Onegmentofrightmandibularramuswithposteriorpartofincisorandm1～3(PC29255),andonegmentofleftmandibularramuswithp4～m3(PC17265).Localitiesandhorizons Shunkt,;mngovǐ,Mongolia,lateearlyOligocene2?lateOligoceneShandMemberofHsandaGolFormation(PC29255);UlaanKhongil(=TatalGol,45°17′50″N,101°37′16″E),;vrhangay,Mongolia,earlyearlyOligoceneTatalMemberofHsandaGolFormation(PC17265).2期 王伴月等:蒙古新发现的渐新世山河狸和松鼠类化石93Diagnosis eethbrachydont,mesostylidconnectedwithmetastylidcrest,mesoconidweak,ectomesolophidweakorabnt;anteroconidandanteriorcingulumabntonp4;anaccessorycrestextendingfromectolophidtohypolophidonm1;metalophidⅡwelldevelopedonm2～3;hypolophidbendsposteriorlytojoinwithposterolophidonp4～m1,butstraighttojoinwithectolophidonm2～ogy ption tericfossaisprominentwithdistinctupperandlowercrests,.3 alviewofleftp4～m3(PC17265);alviewofrightm1～3(PC29255);lleftmandibularramuswithp4～m3(PC29253,holotype),alview;lview94古 脊 椎 动 物 学 报 43卷Table2 iensis(mm)usPC29253(holotype)p4～m3Lm1～3p4LLTrWTaWLm1TrWTaWLm2TrWTaWLm3i2TrWTaWL(a2p)W8.36.22.31.72.21.91.82.22.122.32.421.92.41.9PC29255PC17265PC292546.9PC17246(holotype)6.121.42.12.11.92.12.21.92.22.41.91.92.41.91.81.91.722.11.92.15.31.81.41.81.71.51.72.11.61.821.71.61.91.41.41.11.51.61.331.61.71.51.51.6 Abbreviations:;L(a2p).lengthfromanteriorsidetoposteriorside;;ftrigonid;distinct,stemynarrowanddeeptrigonidbasinisclodposteriorlybyacompletemetalophidⅡ,toconidhasaweakanteriorarm,olophiteriorvalleybetweolophidisshort,aconid,thehighestcusp,toconid,largerthanthemetaconid,islocatednotoppositetothelatterattheanteriormarginofthetooth,plete,highmetalophidⅠisconvexanteriorly,buttheshortmetalophidⅡgonidbasiniswiderthanthatinp4,ssorycrestextendsfromtheectolophidtothebendinghypoloalophidⅡismoredeveloped,teriorvalleyiswiderandthecentralbasinisrelativelysmaller.2期 王伴月等:蒙古新发现的渐新世山河狸和松鼠类化石ssorycrestfromposteriorwallofthemetalophidⅠextendsposterobuccallytoreachoralmostreachtothelingualendofthemetalophidⅡ.ions ison TheabovedescribedspecimensarealmostidenticalwiththoofProsciurusinthebasicfeatures(Wood,1962;Wang,1986):thecheekteetharebrachydont;thetrigonidishigherthanthetalonid;themetaconidshiftsforwardsandtheprotoconidislocatedposteriorlytothemetaconidonm1～3;themetalophidⅠisabntonp4,butcompleteandconvexanteriorlyonm1～3;themesoconidandmesostylidareprent;ore,w,Prosciurusisknowntoinclude7species:us,us,chewaensis,,,cusandP.?shantungensis(Wood,1937,1980;RensbergerandLi,1986;Wang,1987;Korth,1989).,us,us,chewaensis,P.?shantungensis,inhavingweaklydevelopedmesoconidonlowercheekteeth,andmesostylidjoiningwithmetastylidcrestonm1～usinhavingmoreposteriorlylocatedmastericfossa,weaklydevelopedectomesolophid,longermetalophidⅡandhypolophidjoiningwithectolophidonm2andm3,m1andm2beingwiderthanlength;usinhavinglongermetalophidⅡonm2～3,weaklydevelopedectomesolophid,andmoredevelopedbutposteriorlybendinghypolophidjoiningwithposterolophidonp4～m1;chewaensisinhavingincompletemetalophidⅡ,weaklydevelopedectomesolophidonlowermolars,bendingposteriorlyhypolophidjoiningposterolophidonp4～m1,andlackinganterolophidonp4;inhavingmoredevelopedmetalophidⅡ,narrowermesostylid,weaklydevelopedectomesolophid,moredeveloped,transverhypolophidjoiningwithectolophidonm2～3,andlackingcingulumbehindprotoconid;fromP.?shantungensisinhavinglowercrownedteeth,highermetaconid,narrowermesostylid,weaklydevelopedectomesolophidandhypoconulid,lowerhypolophidjoiningwithectolophid;inhavingmoredevelopedmetalophidⅡandhypolophid,smallermesostylid;,anewspecies,.(Fig.4;Table2) Specimen Agmentofrightmandibularramuswithi2,p4～m3(PC29254).Localityandhorizon Shunkt,;mngovǐ,Mongolia;lateearlyOligocene2?ptionandremarks erincisor,completelyprervedinPC29254,islaterallr,inthenewspecimenthep4hasamoredistinctectomesolophid;thehypolophidisgentlycurvedonp4andm1;nodistinctcrestfromtheectolophidtothehypolophidisvisibleonm1;themetalophidⅡisshortonthem2～m3;themesoconidandectomesolophidaremoredistinctonm1～m3;and,finally,alltheteetharesmaller(eTable2).iensis.96古 脊 椎 动 物 学 报 43卷Fig.4 Partialrightmandibularramuswithi2,p4～m3(PC29254)alview;.(Fig.5;Table2) Holotype Agmentofleftmandibularramuswithi2andp4～m2(PC17246).Localityandhorizon UlaanKhongil,;vrhangay,Mongolia;sis eethbrachydont,withshortmetalophidⅡ,lowandtransverhypolophidreachingtoectolophid,well2developedmesoconidandectomesolophid,moreanterobuccallyextendinghypoconid,distinctcingulum;mesostylidconnectedwithmetastylidcrestonp4andisolatedonlowermolars;ogy Pisinnus,Latin,small,little,ption minentmastericfossahasarightangularanstemaconidisbroken,2shapedprotoconidhastwoarms:theanteriorarmalmost2期 王伴月等:蒙古新发现的渐新世山河狸和松鼠类化石97Fig.5 Partialleftmandibularramuswithi2,p4～m2(PC17246,holotype)alview;lviewreachestothebaofthemetaconid;theposteriorarmextendstothemetaconidtoformcomplete,lowmetalophidⅡ.Thostylidisdistinct,butconnectedwithmetastylidcrestandparatedfromtheentoconidbyawidevalley,hemaincuspstheentoconidisthesmallestandlowestone,olophidextendsfromthehypoconidtothebaofthemetalophidⅡ.okanddistinctbuccalcingaconid,higherthantheprotoconid,terisnotlocatedattheanteriormargin,pleteandhighmetalophidⅠalophidⅡostylidisisololophidisasingletransvercrest,tinctlingualcingulumi2isbrokenatits98古 脊 椎 动 物 学 报 43卷gualcingulumisnotsodistinct,ison TheabovedescriptionshowsclearlythatPC17246isalmostidenticalwithProsciurusinbasicfeatures,heknown9speciesofProsciurus(us,us,chewaensis,,,cus,P.?shantungensis,iensis,iensis),inhavingtransver,lowerhypolophidjoiningwithectolophid,moredevelopedcinguluminlowercheekteeth,ersfromation,usinhavinglowerandtransverhypolophidjoiningwithectolophid;usinlengthofm1andm2beingsubequaltoorlongerthanwidth,havingmoreanterobuccallyextendinghypoconidonlowercheekteethandmesostylidconnectingwithmetastylidcrestonp4;chewaensisinhavingincompletemetalophidⅡandmoreanterobuccallyextendinghypoconid;inhavingmoredevelopedandtransverhypolophidjoiningwiththeectolophid;fromP.?shantungensisinhavinglowercrown,highermetaconid,narrowermesostylid,lowerhypolophid,andsmallerhypoconulid;iensisinhavinglowercrown,well2developedmesoconidandectomesolophid,moreanterobuccallyextendinghypoconidonlowercheekteeth,lowerandtransverhypolophidjoiningwithectolophidonp4～m1,isolatedmesostylidonm1～2,ifferencesledustoerectanewspeciesforthespecimenPC17246,sion ProsciurushasbeenknowntobemainlydistributedinNorthAmerica,withonlyafewpoorlypretherfourforms(Prosciuruslohiculus,ptus,P.?cus)werereportedfromAsia(MatthewandGranger,1923;Shevyreva,1971;RensbergerandLi,1986;Wang,1987).However,twoofthem,ptus,wereexcludedfromthisgenuslater(Wang,1986,1987).luswasincludedinAnomoemysoftheCylindrodontidae,ertwospecies,P.?cus,erwiththethreenewformsfromMongolia,tonlyprovesthatthegenusProsciurusdoexistinAsia,butalsoshowsthatProsciumoreimportantisthefactthatsomeoftheAsianspecimple,dustothinkthatsor,thepaucdbettermaterialisneededinordertosolvethisproblemconclusively.3 ConclusionAsisnowknown,inAsiatheOligocenesciuridsincludefourspeciesofthreegenera:gosciurusdangheensisfromDangheareainGansu,China,erialofthetwoformismoresimilartotheNorthAmericancedromurines,especiallyOligospermophilus,eneraofSciuridaewerereportedfromOligoceneofEurope:Palaeosciurus,Heteroxerusand2期 王伴月等:蒙古新发现的渐新世山河狸和松鼠类化石hemajordifferencesofPxerusisdifferentfromKherferencesbetweenOligopetesandKheremareevenlarger(eHeissig,1979).TheabovecomparisonshowsclearlythatKheremhasclorrelationshipswiththeAmericansciuridsratherthanwiththeEuropeanones,materialofProsciurusfoundinMoanOligoceneaplodontidsnowincludeeightspeciesoffourgenera:zakhstan,Haplomysarboraptus,Promeniscomyssinensis,Prosciurusordosicus,P.?shantungensis,iensis,iensis,rosciurusandHaplomysarecommontoAsiaandNorthAmerica,ledgments nKui,QiuZhan2XiangandQiuZhuDingofInstituteofVertebratePaleontologyandPaleoanthropology,ChineAcademyofSciences,fortheirhelpfuldiscussion,ncesArgyropuloAI,morphaandDipodidae(Glires,Mammalia)sRendusAcadSciURSS,25(23):171～175BohlinB,silmammalsfromtheTertiarydepositofTaben2buluk,ntSin,NSC,(8b):1～259BryantJD,McKennaMC,lanatomyandphylogeneticpositionofTsaganomysaltaicus(Mammalia:Rodentia)fromtheHsandaGolFormation(Oligocene),ovit,(3156):1～4HeissigK,ühestenFlughrnchenundprimitiveAiluravinae(Rodentia,Mamm.)ausdemsüddeutschenOligozyerStaatssammalPalonthistGeol,19:139～169HckV,Daxner2HckG,SchmidHPetal.,ene2Miocenediments,fossilsandbasaltsfromtheValleyofLakes(CentralMongolia)—;sterrGeolGes,90:83～125KorthWW,ntidrodents(Mammalia)fromtheOligocene(OrellanandWhitneyan)BruleFormation,aleont,9(4):400～414KorthWW,k:PlenumPress.1～319KorthWW,EmryRJ,llofCedromusandareviewoftheCedromurinae(Rodentia,Sciuridae).JPaleont,65(6):984～994KowalskiK,ntPol,30:147～178MatthewWD,GrangerW,ovit,(102):1～10MengJ,McKennaMC,,394:364～367MinjinB,ocenesciuridfromtheHsandaGolFormation,aleont24(3):753～756()QiuZD邱铸鼎,MiocenemicromammalianfaunafromTunggur,g:SciencePress.1～216(inChinewithEnglishsummary)RensbergerJM,LiCK,osciurinerodentfromShantungProvince,nt,60(3):763～771RusllDE,ZhaiRJ,eongeneofAsia:mammalsandstratigraphy.MémMusNatlHistNatur,SerC,SciTerre(Paris),52:1～488ShevyrevaNS,aleontInstAcadSciUSSR,130:70～86WangBY(王伴月),lAsiat(古脊椎动物学报),24(4):285～294(inChinewithEnglishsummary)WangBY(王伴月),eryofAplodontidae(Rodentia,Mammalia)frommiddleOligoceneofNeiMongol,lAsiat(古脊椎动物学报),25(1):32～45(inChinewithEnglishsummary)WangBY(王伴月),QiuZX(邱占祥),eryofearlyOligocenemammalianfossilsfromDangheArea,Gansu,lAsiat(古脊椎动物学报),42(2):130～143(inChinewithEnglishsummary)WoodAE,of“TheMammalianFaunaoftheWhiteRiverOligocene”byScottWB,mPhilosSoc,NS,28:155～269WoodAE,mPhilSoc,NS,52:1～261WoodAE,mPhilSoc,70(5):1～68
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