但是,西里龍與牠們的演化關係卻不詳。有研究將真腔骨龍歸類於恐龍形類(Dinosauriformes),但卻不排除是原始的鳥臀目恐龍。 Sullivan, R.M. and Lucas, S.G. (1999). "Eucoelophysis baldwini, a new theropod dinosaur from
Lodders, J. Canty, P. Lucas, R. L. Smart, C. G. Tinney, D. Homeier, F. Allard, Ben Burningham, A. Day-Jones, B. Fegley, Miki Ishii, H. R. A. Jones, F. Marocco