Yang T-R, Engler T, Lallensack J N, Samathi A, Makowska M, Schillinger B
Section of Paleontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany.
Division of Geology, National Museum of Natural Science, Guancian Road 1, 40453 Taichung, Taiwan.
Integr Org Biol. 2019 Nov 22;1(1):obz030. doi: 10.1093/iob/obz030. eCollection 2019.
Dinosaur nesting biology has been an intriguing research topic, though dinosaur behaviors were relatively less illuminated because of the constraints of the fossil record. For instance, hatching asynchrony, where eggs in a single clutch hatch at different times, is unique to modern neoavian birds but was also suggested to be present in oviraptorid dinosaurs based on a possible partial clutch of four embryo-containing eggs from Mongolia. Unfortunately, unequivocal evidence for the origination of these eggs from a single clutch is lacking. Here we report a new, better preserved partial oviraptorid clutch with three embryo-containing eggs-a single egg (Egg I) and a pair (Egg II/III)-from the Late Cretaceous Nanxiong Group of Jiangxi Province, China. Geopetal features indicate that the pair of eggs was laid prior to the single egg. Neutron tomographic images in combination with osteological features indicate that the embryo of the single egg is less developed than those of the paired eggs. Eggshell histology suggests that the embryo-induced erosion in the paired eggs is markedly more pronounced than in the single egg, providing a new line of evidence for hatching asynchrony. The inferred hatching asynchrony in combination with previously surmised thermoregulatory incubation and communal nesting behaviors very likely suggests that oviraptorid dinosaurs presented a unique reproductive biology lacking modern analogs, which is contrary to the predominant view that their reproductive biology was intermediate between that of modern crocodiles and birds.
恐龙筑巢生物学一直是一个引人入胜的研究课题，尽管由于化石记录的限制，恐龙的行为相对较少被阐明。例如，孵化异步现象，即同一窝蛋在不同时间孵化，这是现代新鸟亚纲鸟类所特有的，但基于来自蒙古的一窝可能包含四个胚胎的蛋的部分样本，也有人认为窃蛋龙类恐龙也存在这种现象。不幸的是，缺乏明确证据证明这些蛋来自同一窝。在此，我们报告了一个保存更好的新的窃蛋龙类部分窝蛋，它来自中国江西省晚白垩世南雄组，包含三个有胚胎的蛋——一个单蛋（蛋I）和一对蛋（蛋II/III）。地层层序特征表明这对蛋比单蛋先产下。中子断层扫描图像与骨骼特征相结合表明，单蛋中的胚胎比成对蛋中的胚胎发育程度低。蛋壳组织学表明，成对蛋中胚胎诱导的侵蚀明显比单蛋中更显著，为孵化异步提供了新的证据。推断出的孵化异步现象，再加上先前推测的体温调节孵化和群体筑巢行为，很可能表明窃蛋龙类恐龙呈现出一种独特的生殖生物学，缺乏现代类似物，这与它们的生殖生物学处于现代鳄鱼和鸟类之间的主流观点相反。
