Abstract White fibers from a Late Cretaceous dinosaur Shuvuuia deserti stained positive for β-keratin antibodies in a 1999 paper, followed by many similar immunological claims for Mesozoic protein in bones and integument. Antibodies recognize protein epitopes derived from its tertiary and quaternary structure, so such results would suggest long polypeptide preservation allowing for sequencing with palaeobiological implications. However, proteins are relatively unstable biomacromolecules that readily hydrolyze and amino acids exhibit predictable instability under diagenetic heat and pressure. Furthermore, antibodies can yield false positives. We reanalyzed a Shuvuuia fiber using focused ion beam scanning electron microscopy, energy-dispersive X-ray spectroscopy, time-of-flight secondary ion mass spectrometry, and laser-stimulated fluorescence imaging, finding it to be inorganic and composed mainly of calcium phosphate. Our findings are inconsistent with any protein or other original organic substance preservation in the Shuvuuia fiber, suggesting that immunohistochemistry may be inappropriate for analyzing fossils due to issues with false positives and a lack of controls.

中文翻译：

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白垩纪晚期恐龙 Shuvuuia Deserti 羽毛纤维的保存引起了对化石免疫组织化学分析的关注

摘要 在 1999 年的一篇论文中，来自晚白垩世恐龙 Shuvuuia Deserti 的白色纤维对 β-角蛋白抗体染色呈阳性，随后许多类似的免疫学声称对骨骼和外皮中的中生代蛋白质进行了鉴定。抗体识别源自其三级和四级结构的蛋白质表位，因此此类结果表明多肽长期保存，允许进行具有古生物学意义的测序。然而，蛋白质是相对不稳定的生物大分子，容易水解，氨基酸在成岩热和压力下表现出可预测的不稳定性。此外，抗体会产生假阳性。我们使用聚焦离子束扫描电子显微镜、能量色散 X 射线光谱法、飞行时间二次离子质谱法重新分析了 Shuvuuia 纤维，和激光刺激荧光成像，发现它是无机的，主要由磷酸钙组成。我们的发现与 Shuvuuia 纤维中保存的任何蛋白质或其他原始有机物质不一致，这表明由于假阳性和缺乏控制的问题，免疫组织化学可能不适合分析化石。