A new dinosaur egg fossil was recovered from Yudu County, Jiangxi Province, China. Its outer surface exhibits pronounced ornamentation, with highly fused spherulitic eggshell units, well-developed growth lines, and tubular pore canals with smooth margins. These characteristics are highly similar to those of Stromatoolithus pinglingensis, suggesting that the new specimen represents the second oospecies of the oogenus Stromatoolithus documented from China, herein designated as Stromatoolithus yuduensis. Notably, this is also the first relatively complete Stromatoolithus egg fossil recovered from China, filling a gap in the macroscopic study of this oogenus. Comparative analysis indicates that Stromatoolithus differs from all previously recognized oofamilies, justifying the establishment of a new oofamily, Stromatoolithidae. Furthermore, our study suggests that Guegoolithus turolensis, from the Lower Cretaceous of Spain shares key eggshell microstructural characteristics with S. pinglingensis. Therefore, we propose reassigning G. turolensis to the oogenus Stromatoolithus. This reassignment extends the temporal and geographic distribution of Stromatoolithidae to the Early Cretaceous and suggests that stromatoolithid eggs were likely produced by a range of ornithischian dinosaurs, including hadrosauroids.

中国江西省于都县发现一枚新的恐龙蛋化石。该化石外表面饰纹显著，壳单元为高度融合的球粒状结构，生长纹发育良好，孔道呈管状且边缘光滑。上述特征与坪岭叠层蛋(Stromatoolithus pinglingensis)极为相似，表明该标本代表了叠层蛋属(Stromatoolithus)在中国的第二个蛋种——于都叠层蛋(Stromatoolithus yuduensis)。尤为重要的是，这也是中国迄今发现的首枚相对完整的叠层蛋化石，填补了该蛋属在宏观形态学上的研究空白。对比分析显示，叠层蛋与此前已识别的所有蛋科均存在差异，据此建立新蛋科——叠层蛋科(Stromatoolithidae)。此外，产自西班牙下白垩统的Guegoolithus turolensis在蛋壳微观结构关键特征上与坪岭叠层蛋具有一致性，因此建议将其归入叠层蛋属。这一重新归类将叠层蛋科的时空分布范围扩展至早白垩世，并表明叠层蛋类可能由包括鸭嘴龙形类在内的多种鸟臀目恐龙所产。