School of Earth Sciences, University of Bristol, Bristol, United Kingdom.
PLoS One. 2012;7(12):e52289. doi: 10.1371/journal.pone.0052289. Epub 2012 Dec 19.
Therizinosauria is one of the most enigmatic and peculiar clades among theropod dinosaurs, exhibiting an unusual suite of characters, such as lanceolate teeth, a rostral rhamphotheca, long manual claws, and a wide, opisthopubic pelvis. This specialized anatomy has been associated with a shift in dietary preferences and an adaptation to herbivory. Despite a large number of discoveries in recent years, the fossil record for Therizinosauria is still relatively poor, and cranial remains are particularly rare.
METHODOLOGY/PRINCIPAL FINDINGS: Based on computed tomographic (CT) scanning of the nearly complete and articulated skull of Erlikosaurus andrewsi, as well as partial braincases of two other therizinosaurian taxa, the endocranial anatomy is reconstructed and described. The wider phylogenetic range of the described specimens permits the evaluation of sensory and cognitive capabilities of Therizinosauria in an evolutionary context. The endocranial anatomy reveals a mosaic of plesiomorphic and derived characters in therizinosaurians. The anatomy of the olfactory apparatus and the endosseous labyrinth suggests that olfaction, hearing, and equilibrium were well-developed in therizinosaurians and might have affected or benefited from an enlarged telencephalon.
CONCLUSION/SIGNIFICANCE: This study presents the first appraisal of the evolution of endocranial anatomy and sensory adaptations in Therizinosauria. Despite their phylogenetically basal position among maniraptoran dinosaurs, therizinosaurians had developed the neural pathways for a well developed sensory repertoire. In particular olfaction and hearing may have played an important role in foraging, predator evasion, and/or social complexity.
镰刀龙类是兽脚亚目恐龙中最神秘和独特的类群之一，具有不寻常的特征组合，如长矛状的牙齿、头部的角质喙、长的手部爪子和宽阔的耻骨后坐部。这种特殊的解剖结构与饮食习惯的转变和对草食性的适应有关。尽管近年来有大量的发现，但镰刀龙类的化石记录仍然相对较差，头骨遗骸尤其罕见。
方法/主要发现：基于对近完整和关节连接的 Erlikosaurus andrewsi 头骨的计算机断层扫描（CT），以及另外两种镰刀龙类分类单元的部分脑壳，重建和描述了颅腔内部解剖结构。描述的标本具有更广泛的系统发育范围，允许在进化背景下评估镰刀龙类的感觉和认知能力。颅腔内部解剖结构揭示了镰刀龙类中原始和衍生特征的镶嵌体。嗅觉器官和内骨骼迷路的解剖结构表明，嗅觉、听觉和平衡在镰刀龙类中发育良好，可能受到或受益于大脑的扩大。
结论/意义：本研究首次评估了镰刀龙类颅腔内部解剖结构和感觉适应的进化。尽管在手盗龙类恐龙中处于系统发育的基础位置，镰刀龙类已经发展出了用于完善的感觉器官的神经通路。特别是嗅觉和听觉可能在觅食、逃避捕食者和/或社交复杂性方面发挥了重要作用。
