Baurusuchid crocodyliforms as theropod mimics: clues from the skull and appendicular morphology of Stratiotosuchus maxhechti (Upper Cretaceous of Brazil)
Baurusuchid crocodyliforms as theropod mimics: clues from the skull and appendicular morphology of Stratiotosuchus maxhechti (Upper Cretaceous of Brazil)
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模仿兽脚亚目鳄鱼的包鲁鳄：来自 Stratiotosuchus maxhechti（巴西上白垩纪）头骨和附肢形态的线索
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发表时间：
2011
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通讯作者：
A. Kellner
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作者：
D. Riff;A. Kellner
bauusuchidae鳄鱼类通常被解释为活跃的陆地捕食者，但迄今为止只有一些关于这种习惯的积极证据被描述，主要是外部鼻孔和轨道的相对位置。在这里，我们描述了一个完整的bauusuchidae Stratiotosuchus maxhechti标本中支持这一观点的特征，并进行了简约分析以确认它们的系统发育位置。S. maxhechti表现出先前在兽脚亚目头骨中发现的兽脚亚目特征，以及与副矢状突步态相关的颅后特征，表明兽脚亚目和兽脚亚目之间的相似性超出了颅形态。这包括发育良好的髋臼上嵴，相对内侧偏置的股骨头和尾部定向的跟骨结节。肌肉附着物表面的方向表明，大鲵的阑尾运动主要是前后运动，外展明显受限。S. maxhechti具有类似兽脚亚目恐龙的特征，包括髂骨上的“短窝”和坐骨和股骨上的结节，类似于闭孔突和副粗隆。股骨、胫骨和较长的跖骨的相对比例与后suchus比与其他鳄形目更相似。在颅骨中，除了集中在喙部前半部分的兽足畸形（ziphodon）牙齿外，baurusuchids的显著特征是鼻部的融合，这可能与对作用在高姿态颅骨上的进食力的巨大阻力有关。S. maxhechti的尾巴形态强化了Baurusuchidae是巴西东南部上白垩世活跃的陆生捕食者的解释，占据了中小型兽脚亚目恐龙的典型生态位。
The Baurusuchidae crocodyliforms are usually interpreted as active terrestrial predators, but only some positive evidence of such habits has been described to date, mainly the relative position of external nares and orbits. Here we describe features that support this view in a complete specimen of the Baurusuchidae Stratiotosuchus maxhechti, and have executed a parsimony analysis to confirm their phylogenetic position. S. maxhechti exhibits theropodomorph features that have been previously recognized in skulls of the Baurusuchidae, as well as postcranial characteristics related to a parasagittal gait, showing that the similarities between the Baurusuchidae and theropods extend beyond the cranial morphology. These include a well-developed supracetabular crest, a relatively medially offset femoral head and a caudally orientated calcaneal tuber. The orientations of the surfaces for muscular attachments imply that the appendicular movements of S. maxhechti were mainly anteroposterior, with abduction significantly constrained. S. maxhechti presents features that mimic some present in theropods, including a ‘fossa brevis’ on the ilium and tubercles on the ischium and femur similar to the obturator process and accessory trochanter. The relative proportions of the femur, tibia, and longer metatarsal are more similar to those of Postosuchus than to other Crocodylomorpha. In the skull, besides the theropodomorph (ziphodont) dentition concentrated in the anterior half of the rostrum, the baurusuchids are remarkable by the fusion of the nasals, which can be related to a large resistance against feeding forces acting on a high-profile skull. The appendicular morphology of S. maxhechti strengthens the interpretation that the Baurusuchidae were active land-dwelling predators in the Upper Cretaceous of south-eastern Brazil, occuping ecological niches typical of small to medium-sized theropod dinosaurs.
© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, S37–S56.