Schachner Emma R, Manning Phillip L, Dodson Peter
Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Morphol. 2011 Dec;272(12):1464-91. doi: 10.1002/jmor.10997. Epub 2011 Jul 28.
The discovery of a largely complete and well preserved specimen of Poposaurus gracilis has provided the opportunity to generate the first phylogenetically based reconstruction of pelvic and hindlimb musculature of an extinct nondinosaurian archosaur. As in dinosaurs, multiple lineages of basal archosaurs convergently evolved parasagittally erect limbs. However, in contrast to the laterally projecting acetabulum, or "buttress erect" hip morphology of ornithodirans, basal archosaurs evolved a very different, ventrally projecting acetabulum, or "pillar erect" hip. Reconstruction of the pelvic and hindlimb musculotendinous system in a bipedal suchian archosaur clarifies how the anatomical transformations associated with the evolution of bipedalism in basal archosaurs differed from that of bipedal dinosaurs and birds. This reconstruction is based on the direct examination of the osteology and myology of phylogenetically relevant extant taxa in conjunction with osteological correlates from the skeleton of P. gracilis. This data set includes a series of inferences (presence/absence of a structure, number of components, and origin/insertion sites) regarding 26 individual muscles or muscle groups, three pelvic ligaments, and two connective tissue structures in the pelvis, hindlimb, and pes of P. gracilis. These data provide a foundation for subsequent examination of variation in myological orientation and function based on pelvic and hindlimb morphology, across the basal archosaur lineage leading to extant crocodilians.
纤细波波龙一个保存完好的近乎完整的标本的发现，为首次基于系统发育学对一种已灭绝的非恐龙类主龙的骨盆和后肢肌肉组织进行重建提供了机会。和恐龙一样，基干主龙的多个谱系趋同地演化出矢状旁直立的四肢。然而，与鸟颈类主龙侧向突出的髋臼，即“支撑直立”的髋部形态不同，基干主龙演化出了一种非常不同的、腹侧突出的髋臼，即“柱状直立”的髋部。对一种两足的苏铁类主龙的骨盆和后肢肌肉腱系统的重建，阐明了与基干主龙两足行走演化相关的解剖学转变与两足恐龙和鸟类的有何不同。这种重建基于对系统发育相关现存类群的骨骼学和肌肉学的直接检查，以及来自纤细波波龙骨骼的骨骼学关联。这个数据集包括了一系列关于纤细波波龙骨盆、后肢和足部的26块单独肌肉或肌肉群、三条骨盆韧带和两个结缔组织结构的推断（结构的有无、组成部分的数量以及起止点）。这些数据为后续基于骨盆和后肢形态，对通向现存鳄鱼的基干主龙谱系中肌肉学方向和功能的变化进行研究提供了基础。
