Sinosauropteryx, Sinornithosaurus and some other nonavian theropod specimens show open tufted structures that lack a rachis and are strikingly congruent with stage 2 of the model.

• 而中华龙鸟、中国鸟龙与其他非鸟类兽足类标本的羽毛都有开展的簇生结构、缺乏羽轴，与模型中的阶段2吻合，再度令人惊奇。