冠龙手部三维数字建模与初步功能分析

THREE-DIMENSIONAL MODELING OF THE MANUAL DIGITS OF THE THEROPOD DINOSAUR GUANLONG,WITH A PRELIMINARY FUNCTIONAL ANALYSIS

冠龙是一种生活于侏罗纪晚期的基干暴龙类,现已发现的化石皆产于中国新疆准噶尔盆地的石树沟组。本次研究使用激光非接触数据化仪对冠龙标本IVPP V14531的左手进行扫描,用RapidformXOV2软件建立单块骨骼三维数字模型,然后用AutodeskMaya软件关联手部各块骨骼,建立整个手部的功能性三维数字模型。尽管基于骨骼化石对兽脚类恐龙手指活动范围进行推测受制于一些不确定性因素,但我们还是能够给出手指的可能活动范围,来测算兽脚类恐龙手指的背展和屈曲度。对模型的分析显示,冠龙手指Ⅱ和Ⅲ的有限背展度介于基干僵尾龙高棘龙和虚骨龙类当中的恐爪龙之间,有限屈曲度变化范围很大,但在高棘龙和恐爪龙变化范围之内;手指Ⅳ的掌骨和指节间关节几乎没有活动性,第一个指节间关节背展度很大,甚至强于高棘龙,第二个指节间关节活动性和高棘龙相当,第三个指节间关节活动性和恐爪龙相当。这也许暗示兽脚类恐龙在演化过程中,手指背展能力逐渐减弱,而屈曲能力逐步加强。这一演化趋势是否存在还需要更多相关数据来检验。

Guanlong is a basal tyrannosauroid theropod dinosaur from the upper part of the Shishugou Formation of the Junggar Basin in the Xinjiang region of northwest China,which is Late Jurassic in age（Xu et al.,2006）.In this study we evaluated the ranges of flexion and extension at the various joints within the hand of Guanlong,based on laser scans of the well-preserved left manus of the holotype specimen（IVPP V14531）.The scans were processed using Rapidform XOV2 to create three-dimensional digital models of the metacarpals and phalanges,which were then imported into Autodesk Maya and used to construct an articulated model of the complete manus.A system of hierarchically arranged joints was constructed in Maya in order to allow precise three-dimensional positioning of the model, as in scientific rotoscoping studies in which a model is used to duplicate the recorded movements of a living animal（Gatesy et al.,2010）.