Similicaudipteryx

Similicaudipteryx is a genus of theropod dinosaur of the family Caudipteridae. Its fossil remains were recovered from the Jiufotang Formation of northeastern China, dating to the early Cretaceous Period (Aptian stage) about 120 million years ago. The genus contains one described species, Similicaudipteryx yixianensis, which was named in 2008 by He, Wang, and Zhou. The name refers to its similarity to the closely related Caudipteryx and its location near the Chinese Yixian beds.

He and colleagues assigned Similicaudipteryx to the Caudipteridae based on its similarity to Caudipteryx (from the older Yixian Formation, 125 million years ago), especially in the shape of the pubic bones, though these bones are differently proportioned than in Caudipteryx. Similicaudipteryx also differed from its relatives by possessing a dagger-shaped pygostyle (the bone at the end of the tail to which feathers anchor in birds) and several unique features of the back vertebrae. The only other oviraptorosaur reported to have a pygostyle is Nomingia, though the feature is widespread in more advanced birds and appears to have evolved at least twice.