Zhang Shukang, Choi Seung, Kim Noe-Heon, Xie Junfang, Park Yong, Plümper Oliver, Sellés Albert G
Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China.
Sci Adv. 2025 May 30;11(22):eadt1879. doi: 10.1126/sciadv.adt1879.
Secondary eggshell units, though rarely observed in modern avian eggshells, are marked structures in non-avian dinosaur eggshells that offer valuable paleobiological insights. Despite their significance, the origins of secondary eggshell units remain understudied, leading to debates in paleontology, including the hypothesis of an abiogenic origin for these structures. Here, we demonstrate that secondary eggshell units in non-avian dinosaur eggshells are biogenic in nature, based on analyses using advanced microscopic techniques. The structural characteristics of these units suggest a formation mechanism similar to that of turtle and crocodile eggshells, with matrix fibers likely initiating their development. Furthermore, a diminishing presence of secondary eggshell units in non-avian maniraptoran dinosaurs points to the evolution of a more refined physiological process for eggshell formation in this lineage. These findings shed light on the evolutionary trajectory of eggshell biomineralization in dinosaurs and their close relatives.
次生蛋壳单元虽然在现代鸟类蛋壳中很少被观察到，但在非鸟类恐龙蛋壳中却是显著的结构，能提供有价值的古生物学见解。尽管它们很重要，但次生蛋壳单元的起源仍未得到充分研究，这在古生物学领域引发了诸多争论，包括这些结构的非生物起源假说。在此，我们基于先进显微镜技术的分析表明，非鸟类恐龙蛋壳中的次生蛋壳单元本质上是生物成因的。这些单元的结构特征表明其形成机制与龟和鳄鱼的蛋壳相似，基质纤维可能启动了它们的发育。此外，非鸟类手盗龙类恐龙中次生蛋壳单元的存在逐渐减少，这表明该谱系中蛋壳形成的生理过程进化得更为精细。这些发现揭示了恐龙及其近亲蛋壳生物矿化的进化轨迹。
