Brink K S, Reisz R R, LeBlanc A R H, Chang R S, Lee Y C, Chiang C C, Huang T, Evans D C
1] Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada [2] Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St. Toronto, Ontario, M5S 3B2, Canada.
1] Department of Biology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario, L5L 1C6, Canada [2] Department of Optics and Photonics, National Central University, Jhongli City, Taoyuan 32001, Taiwan.
Sci Rep. 2015 Jul 28;5:12338. doi: 10.1038/srep12338.
Tooth morphology and development can provide valuable insights into the feeding behaviour and evolution of extinct organisms. The teeth of Theropoda, the only clade of predominantly predatory dinosaurs, are characterized by ziphodonty, the presence of serrations (denticles) on their cutting edges. Known today only in varanid lizards, ziphodonty is much more pervasive in the fossil record. Here we present the first model for the development of ziphodont teeth in theropods through histological, SEM, and SR-FTIR analyses, revealing that structures previously hypothesized to prevent tooth breakage instead first evolved to shape and maintain the characteristic denticles through the life of the tooth. We show that this novel complex of dental morphology and tissues characterizes Theropoda, with the exception of species with modified feeding behaviours, suggesting that these characters are important for facilitating the hypercarnivorous diet of most theropods. This adaptation may have played an important role in the initial radiation and subsequent success of theropods as terrestrial apex predators.
牙齿的形态和发育能够为已灭绝生物的进食行为及进化提供有价值的见解。兽脚亚目恐龙是主要以捕食为生的唯一恐龙类群，其牙齿的特征是具刃齿，即在其切割边缘有锯齿（小齿）。具刃齿现今仅在巨蜥科蜥蜴中存在，但在化石记录中更为普遍。在此，我们通过组织学、扫描电子显微镜和同步辐射傅里叶变换红外光谱分析，首次提出了兽脚亚目恐龙具刃齿发育的模型，揭示出先前推测用于防止牙齿断裂的结构，实际上最初是为了在牙齿的整个生命周期中塑造并维持特有的小齿而进化的。我们表明，这种独特的牙齿形态和组织复合体是兽脚亚目恐龙的特征，但具有特殊进食行为的物种除外，这表明这些特征对于大多数兽脚亚目恐龙适应超级食肉饮食至关重要。这种适应性可能在兽脚亚目恐龙作为陆地顶级捕食者的最初辐射扩散及随后的成功中发挥了重要作用。
