辽宁西部早白垩世义县组一新驰龙类
1)
徐 星 汪筱林
(中国科学院古脊椎动物与古人类研究所 北京 100044)摘要：我国辽西早白垩世义县组底部陆家屯层近年来产出大量恐龙和其他脊椎动物化石，其中包括兽脚类恐龙当中的伤齿龙类和窃蛋龙类(Xu ,2002)。本文报道该层位产出的一件驰龙类化石标本。通过对比研究，我们确认这一标本不同于热河群已知的其他3种驰龙类，并建立了驰龙类的一个新属种：陆家屯纤细盗龙(Graciliraptor sp.nov.)。
驰龙类最初发现于北美晚白垩世地层中(Matthew and Brown ,1922)，随后在蒙古晚白垩世
地层中也有发现(Osborn ,1924)；现在已知驰龙类的化石记录主要集中在北美和中亚地区的白垩纪地层中(Xu ,2002)。千禧中国鸟龙(Sinornithosaurus millenii )曾代表最早的确定无疑的驰龙属种(Xu et al.,1999)，其生存时代大约为125Ma (S wisher et al.,1999)。陆家屯纤细盗龙正型标本产于义县组底部陆家屯层，其上覆和下伏岩层的同位素年代分别为128Ma 和139Ma (S wisher et al.,2001)。因此，陆家屯纤细盗龙代表已知最早的驰龙属种。
陆家屯纤细盗龙和其他驰龙类共享以下近裔特征：尾椎前关节突和脉弧极度加长、上颌
齿后缘锯齿明显大于前缘锯齿和指节III -2明显缩短。陆家屯纤细盗龙的以下近裔特征区别于其他驰龙类：中部尾椎有一板状结构连接左右后关节突、中部尾椎椎体极细长(椎体长度和宽度比率约8.6)、第1指爪明显小于第2指爪、第3掌骨近端明显膨大、胫骨细长(估计的长度和中部骨干直径比率约为28)、胫骨近端骨干横截面方形、距骨内髁明显向后膨大和第2跖骨远端明显宽于其他跖骨。
系统发育分析表明辽西的驰龙类构成一个单系类群。这一类群代表驰龙类的一个早期
分支，对于了解驰龙类的早期演化具有重要意义。一方面，辽西驰龙类的发现为鸟类和驰龙类具有很近的亲缘关系提供了更多证据。辽西驰龙类桡骨明显比尺骨纤细，半月形腕骨主要与第2掌骨关联，第1手指明显缩短以及趾爪弯曲度大，这些特征与早期鸟类非常相近(Chi 2appe et al.,1996)。另一方面，辽西的驰龙类也显示出与伤齿龙类的更多相似性，比如它们后足和尾椎的一些特征相对其他驰龙类而言更接近伤齿龙类(N orell and Makovicky ,1997)。辽西驰龙类的发现虽然大大缩短了驰龙类、鸟类和伤齿龙类的形态差距，但也为这些类群的演化带来了更多的不相容性，表明向鸟类演化的过程是不均一的。
陆家屯纤细盗龙代表发现于热河群的第4种驰龙类，显示了驰龙类在早白垩世时期具有
很高分异度。但已知的早期驰龙类在形态上非常相似，结合其他方面的证据，推测驰龙类的早期演化以快速分异为特征，这似乎不同于其姐妹群———伤齿龙类，相对而言，伤齿龙类的早期演化以快速的形态变化为特征。
关键词：辽宁西部，早白垩世，义县组，驰龙类
中图法分类号:Q915.864 文献标识码:A 文章编号:1000-3118(2004)02-0111-09
1)国家自然科学基金委员会创新群体基金、国家重点基础研究发展规划项目(编号:G 2000077700)和国家自然科学基金委员会杰出青年基金(编号:40125006)资助。
收稿日期:2003-11-20
第42卷 第2期2004年4月 古脊椎动物学报V ERTE BRAT A P A L A SIATICA
pp.111～119figs.1～4
211古 脊 椎 动 物 学 报 42卷
A NEW DR OMAEOSAUR(DIN OSAURIA:THER OPODA)FR OM THE
EAR LY CRETACEOUS YIXIAN FOR MATION OF
WESTERN LIAONING
X U X ing W ANG X iao2Lin
(Institute o f Vertebrate Paleontology and Paleoanthropology,Chine Academy o f Sciences Beijing100044) Abstract A specimen collected from the Early Cretaceous lowest part of Y ixian F ormation of Liaoning,
n ortheastern China,reprents a new genus and species of dromaeosaurid theropod.It com pris a fragmen2fantastic
tary maxilla with s ome teeth,a few caudals,alm ost com plete fore limbs,and partial hind limbs and is here
named Graciliraptor sp.n ov.Distinctive characteristics of the new species include a
laminal structure connecting the postzygapophys of middle caudals,middle caudals extremely long and
bribeslender,small manual ungual I,proximal end of metacarpal III strongly ex panded,proximal tibiotarsus shaft
rectangular in cross ction,astragalar medial condyle significantly ex panded posteriorly,metatarsal II dis2
tally much wider than the other metatarsals and long and slender pedal phalanx III21.Being the earliest
definitive dromaeosaurid species kn own to date,G.lujiatunensis provides new in formation im portant for un2
derstanding the early ev olution of the group.On one hand,G.lujiatunensis displays a few features similar
to th o of basal birds,such as caudals significantly elongated,milunate carpal small and primarily con2
tacting metacarpal II,and manual digit I sh ort,providing further evidence for a clo relationship between
the Dromaeosauridae and the Aves;on the other hand,it is similar to trood ontids in s ome features on the
caudals.T he discovery of G.lujiatunensis als o indicates a high diversity of the Dromaeosauridae in the Ear2
ly Cretaceous Jeh ol Biota.C ombined with other lines of evidence,it is in ferred that the Dromaeosauridae
rapidly diversified tax on omically but remained relatively stable m orph ologically in the early ev olution of the
group.
K ey w ords Western Liaoning,Early Cretaceous,Y ixian F ormation,Dromaeosauridae
1 Introduction
special english
Originally discovered from the Late Cretaceous North America(Matthew and Brown,1922), dromaeosaurids are now known to have a much wider distribution both geographically and stratigrap
h2 ically(Osborn,1924;Sues,1978;Barsbold,1983;K irkland et al.,1993;Perle et al.,1999; Xu et al.,1999,2000).The earliest fossils definitively referable to the Dromaeosauridae are from the shales of the lower Y ixian F ormation(Xu et al.,1999;Ji et al.,2001),which is dated as about125Ma(S wisher et al.,1999).Here we describe a new dromaeosaurid specimen that was collected from the lowest part of the Y ixian F ormation that is at least3million2year older than Sinor2 nithosaurus2fossil2bearing beds(S wisher et al.,2001).It is therefore the oldest definitive dro2 maeosaurid,and allows us to review the distribution of s ome characters that are im portant for under2 standing the early ev olution of the Dromaeosauridae.
2 Systematic paleontology
Theropoda Marsh,1881
Maniraptora G authier,1986
Drom aeosauridae Matthew et B row n,1922
Graciliraptor sp.nov.
(Figs.1～3)
H olotype I VPP V13474(Institute of Vertebrate Paleontology&Paleoanthropology,Bei2
jing ),a fragmentary maxilla with s ome teeth ,a few caudals ,alm ost com plete forelimbs ,and partial hindlimbs.
图1 陆家屯纤细盗龙(新属新种)正型标本(I VPP V 13474)，比例尺=1cm
Fig.1 H olotype of Graciliraptor sp.nov.(I VPP V 13474),scale bar =1cm
A.上颌齿外侧视s ome maxillary teeth in lateral view ;
B.中部尾椎背视dorsal view of middle caudals ;
C.
中部尾椎腹视ventral view of middle caudals
简字说明Abbreviations :l.lamina 板状结构;pz.postzygapophysis 后关节突;rc.rod 2like extensions of caudals
尾椎的棒状结构;vs.ventral sulcus 腹沟
Etymology The generic name is derived from the slender limbs and tail of the animal (gra 2cilis ,L.slender ),and the su ffix “raptor ”,comm only ud for dromaeosaurid dinosaur names.The specific name “Lujiatun ”refers to the village near which the holotype was found.
Locality and horizon Lujiatun ,Beipiao City ,western Liaoning ,China ;the lowest member of the Y ixian F ormation (Hauterivian ;S wisher et al.,1999,2001).
Diagnosis Graciliraptor lujiatunensis can be differentiated from all other known dromaeosaurid species bad on the following derived features :a laminal structure connecting the postzygapophys of middle caudals ;extremely long and slender middle caudals ;ungual of manual digit I much small 2er than that of manual digit II ;proximal end of metacarpal III strongly expanded ;extremely slender tibiotarsus ;proximal tibiotarsus shaft rectangular in cross ction ;astragalar medial condyle signifi 2
小学六年级英语上册>got3112期 徐 星等：辽宁西部早白垩世义县组一新驰龙类
411古 脊 椎 动 物 学 报 42卷cantly expanded posteriorly;metatarsal II distally much wider than the other metatarsals;and long and slender pedal phalanx III21.
3 Description
The holotype of G.lujiatunensis might reprent an adult animal as indicated by the partial fu2 sion of the astragalus and calcaneum to the tibia.
The skull is reprented only by a partial left maxilla with a few teeth(Fig.1A).The anterior teeth appear to have no rrations on both anterior and posterior carinae,but the tips are all broken and the might have been rrated.The middle and posterior teeth are similar to tho of the ve2 lociraptorines in that the posterior rrations are significantly larger than the anterior ones(Currie, 1995).
T en caudals are prerved on the holotype.The centra of the middle caudals are significantly elongated(Figs.1B,C).As in other dromaeosaurids,the prezygapophys are extremely long, forming bundle2like structures.Unusually a laminal structure is developed connecting the tw o post2 zygapophys,covering the anterior one2eighth of the succeeding caudal.The chevrons attached to the middle caudals are similar to tho of other dromaeosaurids in forming a rod2like structure except for s ome minor differences such as that both anterior and posterior process of the chevrons are bi2 furcated in ventral view and the posterior process appears als o to be elongated,though not as elon2图2 陆家屯纤细盗龙(新属新种)正型标本(I VPP V13474)，比例尺=1cm Fig.2 H olotype of Graciliraptor sp.nov.(I VPP V13474),scale bar=1cm
A.右前肢right forelimb;
B.左前肢left forelimb
简字说明ale中央骨;dc.deltopectoral crest三角胸嵴;ft.flex or tubercle屈肌结节;
h.humerus肱骨;I21to III24.manual phalanx I21to III24指节I21～III24;acarpal I2III第1～第
3掌骨;dial projection内侧突;r.radius桡骨;ra.radiale桡侧掌骨s.milunate carpal
半月形腕骨;u.ulna尺骨麻烦的英文
初一英语试题
gated as the anterior
圣诞节祝福语英文版
process.
图3 陆家屯纤细盗龙(新属新种)正型标本(I VPP V 13474)，比例尺=1cm
Fig.3 H olotype of Graciliraptor sp.nov.(I VPP V 13474),scale bar =1cm
A.左侧胫跗骨和腓骨前视left tibiotarsus and fibula in anterior view ;
B.左侧距骨和跟骨远端视left astra 2galus and calcaneum in distal view ;
C.右侧胫跗骨外侧视right tibiotarsus in lateral view ;cfs
D.右侧胫跗骨后视right tibiotarsus in posterior view ;
E.左侧跖骨腹视left metatarsus in ventral view ;
F.左侧第2趾内侧视
left pedal digit II in medial view ;G.右侧III 21和III 22趾内侧视right pedal phalanges III 21and III 22
美音音标in medial view
简字说明Abbreviations :ap.ascending process 上升支;c.calcaneum 跟骨;f.fibula 腓骨;fc.fibular crest 腓骨嵴;gr.groove 槽;II 21to III 22.pedal phalanx II 21to pedal phalanx III 22趾节II 21～III 22;lc.lateral condyle 外髁;mc.medial condyle 内髁;mt II atarsals II 2I V 第2～第4跖骨;pvh.proxim oventral heel
近端腹跟突;rd.ridge 脊An alm ost com plete right forelimb and a partial left forelimb were prerved on the holotype ,including s ome carpal elements (Fig.2).The humerus is long and slender ,with a relatively short deltopectoral crest.The ulna is com paratively long ,about 86%the humeral length ,which is pro 2portionately longer than that in other dromaeosaurids.The radius is much thinner than the ulna ,about 53%the thickness of the latter at the mid 2length.The manus is long ,about 130%the length of the humerus ,a ratio larger than that in other dromaeosaurids (Xu ,2002).The milunate is small in size com pared with m ost other non 2avian maniraptorans ,covering only the proximal end of metacarpal II.Metacarpal I is stout and short ,less than one third the length of metacarpal II.Metacarpal II is long and com paratively robust.Metacarpal III is slightly shorter and much thinner than metacarpal II ,and is bowed laterally.Unlike in other dromaeosaurids ,the proximal end of metacarpal III is quite deep dors oventrally ,even deeper than that of metacarpal II.The manual pha 2langeal formula is 22324as in m ost coelurosaurians.Manual phalanx I 21is relatively short.Phalanx
I 22,the ungual of digit I ,is strongly curved ,and has a m oderately developed flex or tubercle proxi 2m oventally and a lip proxim odorsally.Phalanx II 21is the m ost robust of the phalanges.Phalanx II 22is longer than phalanx II 21.Phalanges of digit III are much thinner than tho of digit II.Phalanx III 21is significantly longer than phalanx III 22.As in s ome dromaeosaurids ,a prominent ventral heel is prent on the proximal end of phalanx III 22.
M ost of the left tibiotarsus and part of the right tibiotarsus and femur are prerved (Figs.3A ～D ).The m ost conspicuous feature of the tibiotarsus is its slenderness.The estimated length/midshaft 2diameter ratio is about 28,larger than that in all known non 2avian theropods.The proximal end of the tibiotarsus is not prerved and the prerved proximal shaft is sub 2quadrangular and the distal shaft oval in cross ction.In anterior view the fibular crest is straight for m ost of its length
5112期 徐 星等：辽宁西部早白垩世义县组一新驰龙类
