The paleontologist Paul Sereno, in 2005, conceived the concept Ornithomimiformes, defining them as all species closer to Ornithomimus edmontonicus than to Passer domesticus.

• 因为塞里诺将似鸟龙下目重新定义为较狭隘的范围，所以必须建立起一个演化支，来包含阿瓦拉慈龙科与似鸟龙下目两个姐妹生物群；