不連接,以及堅固的尾部肋骨,而被歸類於厚頭龍類。後來發現恥骨與髖臼連接,而尾部肋骨其實是薦骨部位的肋骨。狹盤龍的彎曲坐骨、缺少閉孔(Obturatorforamen),這是其他厚頭龍類沒有的特徵。 目前狹盤龍被認為屬於角龍亚目。 Stenopelix in The Dinosaur Encyclopaedia
Remarkable features of the hind limb and pelvic girdle include a large obturatorforamen similar in size to that of therians, a large parafibula, and the presence