Bristol Palaeobiology Group, School of Earth Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol, BS8 1TQ, UK.
Sci Rep. 2023 Oct 25;13(1):18242. doi: 10.1038/s41598-023-45444-1.
Ankylosaurs were important megaherbivores of Jurassic and Cretaceous ecosystems. Their distinctive craniodental anatomy and mechanics differentiated them from coexisting hadrosaurs and ceratopsians, and morphological evidence suggests dietary niche partitioning between sympatric ankylosaurids and nodosaurids. Here, we investigate the skull biomechanics of ankylosaurs relative to feeding function. First, we compare feeding functional performance between nodosaurids and ankylosaurids applying finite element analysis and lever mechanics to the skulls of Panoplosaurus mirus (Nodosauridae) and Euoplocephalus tutus (Ankylosauridae). We also compare jaw performance across a wider sample of ankylosaurs through lever mechanics and phylogenetic comparative methods. Mandibular stress levels are higher in Euoplocephalus, supporting the view that Panoplosaurus consumed tougher foodstuffs. Bite force and mechanical advantage (MA) estimates indicate that Panoplosaurus had a relatively more forceful and efficient bite than Euoplocephalus. There is little support for a role of the secondary palate in resisting feeding loads in the two ankylosaur clades. Several ankylosaurs converged on similar jaw mechanics, while some nodosaurids specialised towards high MA and some ankylosaurids evolved low MA jaws. Our study supports the hypothesis that ankylosaurs partitioned dietary niches in Late Cretaceous ecosystems and reveals that the two main ankylosaur clades evolved divergent evolutionary pathways in skull biomechanics and feeding habits.
甲龙是侏罗纪和白垩纪生态系统中重要的巨型草食动物。它们独特的颅面解剖结构和力学特性使它们有别于同时代的鸭嘴龙类和角龙类，形态学证据表明，共生的甲龙类和结节龙类在食性上存在生态位分化。在这里，我们研究了甲龙类相对于进食功能的头骨生物力学。首先，我们通过有限元分析和杠杆力学，比较了尖角龙（结节龙科）和包头龙（甲龙科）头骨的进食功能表现。我们还通过杠杆力学和系统发育比较方法，比较了更广泛的甲龙类样本的咀嚼性能。Euoplocephalus 的下颌骨应力水平较高，支持 Panoplosaurus 食用更坚韧食物的观点。咬合力和机械优势（MA）估计表明，与 Euoplocephalus 相比，Panoplosaurus 的咬合力更强、效率更高。在两个甲龙类群中，次生腭在抵抗进食负荷方面的作用很小。一些甲龙类动物的下颚力学特性趋同，而一些尖角龙类动物专门进化出了高 MA，而一些甲龙类动物则进化出了低 MA 的下颚。我们的研究支持了甲龙类在晚白垩纪生态系统中存在食性生态位分化的假说，并揭示了两个主要的甲龙类群在头骨生物力学和进食习性方面进化出了不同的进化途径。
