Table S1 from A fossil protein chimera; difficulties in discriminating dinosaur peptide sequences from modern cross-contamination

A decade ago, reports that organic-rich soft tissue survived from dinosaur fossils were apparently supported by proteomics-derived sequence information of exceptionally well-preserved bone. This initial claim to the sequencing of endogenous collagen peptides from an approximately 68-Myr <i>Tyrannosaurus rex</i> fossil was highly controversial, largely on the grounds of potential contamination from either bacterial biofilms or from laboratory practice. In a subsequent study, collagen peptide sequences from an approximately 78 Myr <i>Brachylophosaurus canadensis</i> fossil were reported which has remained largely unchallenged. However, the endogeneity of these sequences relies heavily on a single peptide sequence, apparently unique to both dinosaurs. Given the potential for cross-contamination from modern bone analysed by the same team, here we extract collagen from bone samples of three individuals of ostrich, <i>Struthio camelus</i>. The resulting LC–MS/MS data were found to match all of the proposed sequences for both the original <i>Tyrannosaurus</i> and <i>Brachylophosaurus</i> studies. Regardless of the true nature of the dinosaur peptides, our finding highlights the difficulty of differentiating such sequences with confidence. Our results not only imply that cross-contamination cannot be ruled out, but that appropriate measures to test for endogeneity should be further evaluated.

十年前，有关恐龙化石中留存富含有机物软组织的报道，似乎得到了保存极为完好的骨骼的蛋白质组学（proteomics）衍生序列信息的佐证。这一针对约6800万年前霸王龙（Tyrannosaurus rex）化石中内源性胶原蛋白肽测序的初步主张，引发了极大争议，其主要依据是该结果可能受到细菌生物膜或实验室操作带来的污染。
在后续的一项研究中，研究人员报道了约7800万年前亚冠龙（Brachylophosaurus canadensis）化石中的胶原蛋白肽序列，该结论迄今基本未受到质疑。然而，这些序列的内源性（endogeneity）很大程度上依赖于仅一条似乎为两种恐龙所特有的肽段。
鉴于同一团队分析现代骨骼样本时存在交叉污染的潜在风险，本研究从3只鸵鸟（Struthio camelus）的骨骼样本中提取了胶原蛋白。后续的液相色谱-串联质谱法（LC–MS/MS）检测数据显示，其匹配了原始霸王龙与亚冠龙两项研究中提出的全部序列。
无论恐龙肽段的真实性质如何，我们的发现都凸显了准确且有把握地区分此类序列的难度。本研究结果不仅表明无法排除交叉污染的可能性，还指出应当进一步评估用于验证内源性的合理检测措施。