研究人员表示，由于大型兽脚类恐龙的牙齿尺寸巨大，且在系统发育上与鳄类有关联，因此在重建时经常暴露其边缘的齿部。
研究人员利用多代理方法检验了这一假说。对一系列的兽脚类和现存蜥蜴的头骨长度和牙齿大小进行回归，研究人员证实兽脚类恐龙牙齿被口外组织（齿龈和唇鳞）完全覆盖是合理的，并且与在活体小齿类羊膜动物中观察到的模式一致。对鳄类和包括霸王龙在内的兽脚类恐龙的牙齿组织学分析进一步表明，最可能的情况是在闭口时口外组织完全覆盖边缘牙。这改变了人们对这些标志性掠食者的外观和口腔构造的看法，并且对人们解释其他具有大牙齿的陆生动物具有广泛的意义。
附：英文原文
Title: Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology
Author: Thomas M. Cullen, Derek W. Larson, Mark P. Witton, Diane Scott, Tea Maho, Kirstin S. Brink, David C. Evans, Robert Reisz
Issue&Volume: 2023-03-31
Abstract: Large theropod dinosaurs are often reconstructed with their marginal dentition exposed because of the enormous size of their teeth and their phylogenetic association to crocodylians. We tested this hypothesis using a multiproxy approach. Regressions of skull length and tooth size for a range of theropods and extant varanid lizards confirm that complete coverage of theropod dinosaur teeth with extraoral tissues (gingiva and labial scales) is both plausible and consistent with patterns observed in living ziphodont amniotes. Analyses of dental histology from crocodylians and theropod dinosaurs, including Tyrannosaurus rex, further indicate that the most likely condition was complete coverage of the marginal dentition with extraoral tissue when the mouth was closed. This changes our perceptions about the appearance and oral configuration of these iconic predators and has broad implications for our interpretations of other terrestrial animals with large teeth.
DOI: abo7877
Source: https://www.science.org/doi/10.1126/science.abo7877