窃蛋龙类是一类形态特殊的兽脚类恐龙，它们的头骨高度特化，而且具有护卵习性。窃蛋龙类有很多特征与鸟类相似，对研究鸟类起源具有重要意义。由于长时间没有发现早期物种，窃蛋龙类在兽脚类恐龙的系统发育位置还存在很多争议。20世纪90年代以来，在中国辽宁西部早白垩世热河生物群发现以尾羽龙科为代表的早期窃蛋龙类，部分尾羽龙科恐龙的化石标本还保存有羽毛等软组织和胃石，为研究窃蛋龙类的早期演化、生活习性、羽毛及其他软组织演化等提供了重要信息。2019年研究的干戚刑天龙为窃蛋龙类手部和胸骨的演化提供了新的认识。

Oviraptorosauria is an unusual group of Theropods, which has a highly specialize skull, and a habit of protecting their eggs. Oviraptorosauria possess some characters similar to bird, the studies of this group have great significance for the origin of the bird. Because of the loss of the early species, there was dispute about the classification of Oviraptorosauria among Theropods. Since 1990s, several early oviraptorosaurids, including Caudipteridae, has been found from the Early Cretaceous Jehol Biota of western Liaoning, China. Some caudipterid specimens preserved the soft tissues such as the feather, and the gastroliths. The study of this group gives important information of the early evolution and the habit of Oviraptorosauria, the evolution of the feather and other soft tissues. A new caudipterid species Xingtianosaurus ganqi, which was reported in 2019, provided new understanding of the evolution of the manus and the sternum along coelurosauria.