Peterson Joseph E, Daus Karsen N
Department of Geology, University of Wisconsin Oshkosh, Oshkosh, WI, United States of America.
PeerJ. 2019 Mar 4;7:e6573. doi: 10.7717/peerj.6573. eCollection 2019.
Theropod dinosaur feeding traces and tooth marks yield paleobiological and paleoecological implications for social interactions, feeding behaviors, and direct evidence of cannibalism and attempted predation. However, ascertaining the taxonomic origin of a tooth mark is largely dependent on both the known regional biostratigraphy and the ontogenetic stage of the taxon. Currently, most recorded theropod feeding traces and bite marks are attributed to adult theropods, whereas juvenile and subadult tooth marks have been rarely reported in the literature. Here we describe feeding traces attributable to a late-stage juvenile on a caudal vertebra of a hadrosaurid dinosaur. The dimensions and spacing of the traces were compared to the dentition of maxillae and dentaries of different ontogenetic stages. These comparisons reveal that the tooth marks present on the vertebra closely match the maxillary teeth of a late-stage juvenile specimen histologically determined to be 11-12 years of age. These results demonstrate that late-stage juvenile and subadult tyrannosaurs were already utilizing the same large-bodied food sources as adults despite lacking the bone-crushing abilities of adults. Further identification of tyrannosaur feeding traces coupled with experimental studies of the biomechanics of tyrannosaur bite forces from younger ontogenetic stages may reveal dynamic dietary trends and ecological roles of throughout ontogeny.
兽脚亚目恐龙的觅食痕迹和齿痕为社会互动、觅食行为以及同类相食和捕食未遂的直接证据提供了古生物学和古生态学意义。然而，确定齿痕的分类起源在很大程度上既取决于已知的区域生物地层学，也取决于该分类单元的个体发育阶段。目前，大多数已记录的兽脚亚目恐龙觅食痕迹和咬痕都归因于成年兽脚亚目恐龙，而幼年和亚成年个体的齿痕在文献中很少被报道。在此，我们描述了一只晚期幼年个体在一只鸭嘴龙类恐龙尾椎骨上留下的觅食痕迹。将这些痕迹的尺寸和间距与不同个体发育阶段的上颌骨和齿骨的齿列进行了比较。这些比较表明，椎骨上的齿痕在组织学上与一个经测定为11至12岁的晚期幼年个体标本的上颌牙齿紧密匹配。这些结果表明，晚期幼年和亚成年霸王龙尽管缺乏成年个体的骨骼压碎能力，但已经在利用与成年个体相同的大型食物来源。进一步识别霸王龙的觅食痕迹，并结合对幼年个体发育阶段霸王龙咬合力生物力学的实验研究，可能会揭示霸王龙在整个个体发育过程中的动态饮食趋势和生态作用。
