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董氏中华盗龙(兽脚类:异特龙超科)脑颅新知:筛区、颅腔剖解和具气腔

2012年第50卷 第2期: 85-101

发表日期:2012-04-23来源:放大 缩小

编辑:Ariana PAULINA CARABAJAL, Philip J. CURRIE

摘要:董氏中华盗龙(Sinraptor dongi)是来自中国西北部新疆侏罗纪石树沟组上部的一种大型兽脚类。其正型标本包括了保存完好的脑颅,这是在最近的化石修理中额外发现的。脑颅中骨化筛骨的横切面为U形。在脑颅的剖解方位,蝶筛骨和眶蝶骨之间有一未骨化空间,表明该恐龙存活时具有软骨质的中隔蝶骨。利用乳胶颅腔模型和CT扫描技术对颅腔和含气隐窝的形态进行了研究,发现了一些此前未描述过的特点。其中尤为引人注目的是,发育良好的尾鼓室隐窝[一般认为是虚骨龙类(coelurosaurs)的典型特征]以及基蝶骨隐窝和相关气腔的内部形态。侧鼓室隐窝和基蝶骨隐窝有纵向通道连接,很可能同时具有气腔和血管功能。模型也表明,颅腔没有髓质隆起,脑绒球隐窝的开孔沙漏状。若不包含嗅束和嗅球,颅腔容积为95 ml, 脑容商在其他坚尾龙类(tetanurans)的范围内。虽然这些类群的第II-IV对脑神经相对位置各有差异,但前脑、中脑和后脑之间的角度与鲨齿龙类(carcharodontosaurids)[鲨齿龙(Carcharodontosaurus)及南方巨兽龙(Giganotosaurus)]相似。第IX, XXI对脑神经穿过一个半月形的孔。在异特龙超科(Allosauroidea)中,中华盗龙(Sinraptor)在形态颅腔上与鲨齿龙、南方巨兽龙和异特龙(Allosaurus)比与高棘龙(Acrocanthosaurus)更相似。

关键词:中国,侏罗系,异特龙类,脑颅,古神经学

卷期:50 02

 

 

NEW INFORMATION ON THE BRAINCASE OF SINRAPTOR DONGI (THEROPODA: ALLOSAUROIDEA): ETHMOIDAL REGION, ENDOCRANIAL ANATOMY, AND PNEUMATICITY

 

Ariana PAULINA CARABAJAL, Philip J. CURRIE

 

 

Abstract  Sinraptor dongi is a large theropod from the upper Shishugou Formation (Jurassic) of Xinjiang in northwestern China. The holotype includes a well-preserved braincase that recently benefited from additional preparation. The ossified ethmoidal elements are U-shaped in cross-section. When placed in anatomical position in the braincase, an unossified space remains between the sphenethmoid and the orbitosphenoid, suggesting there was a cartilaginous septosphenoid when the animal was alive. The morphology of the endocranial cavity and pneumatic recesses was studied using a latex endocast and CT scans. This led to the recognition of some traits that have not been previously described. The presence of a well developed caudal tympanic recess (generally considered as characteristic of coelurosaurs) is particularly interesting, as is the internal morphology of the basisphenoidal recess and its associated pneumatic cavities. There is a longitudinal passage connecting the lateral tympanic recess with the basisphenoidal recess that probably had both pneumatic and vascular functions. Endocranially, there is no medullar eminence, and the opening for the floccular recess is hourglass-shaped. The volume of the endocranial cavity, excluding the olfactory tract and bulbs, is 95 ml, and the encephalization quotient falls within the range calculated for other basal tetanurans. The angles formed between forebrain, midbrain and hindbrain are similar to those in carcharodontosaurids (Carcharodontosaurus and Giganotosaurus), although the relative positions of cranial nerves II-IV varies amongst these taxa. Cranial nerves IX, X and XI pass through a single half-moon-shaped opening. Within Allosauroidea, the cranial endocast of Sinraptor is morphologically more similar to those of Allosaurus, Carcharodontosaurus and Giganotosaurus than to that of Acrocanthosaurus.

Key words  China, Jurassic, allosauroids, braincase, paleoneurology

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