Eucoelophysis (meaning "true hollow form") is a genus of silesaurid dinosauriform from the Late Triassic (Norian) period Chinle Formation of New Mexico.
Neither the Snyder Quarry specimens nor the material originally assigned to C. longicollis were found to share features with Eucoelophysis by Ezcurra, who identified them instead as indeterminate coelophysoids.
[6][7] Independent of Ezcurra, American paleontologists Sterling Nesbitt, Randall Irmis and William Parker reviewed the Late Triassic theropods of North America in 2007, including Eucoelophysis.
[2] Additional isolated material potentially referrable to Eucoelophysis was identified from the nearby Hayden Quarry of the Chinle Formation by Irmis and colleagues in 2007, including a dentary, ilium, and a femur.
Though there is not clear overlap between the skull bones and the diagnostic elements of Eucoelophysis, the hindlimb material can be confidently referred and only a single silesaurid is presumed to have been present at the locality.