Sepkoski's compendium of marine fossil genera has it classified as an eel, but it has also been previously classified in the Elopiformes and the Osteoglossomorpha.[2] More recent studies have affirmed it as being an osteoglossomorph, and have suggested that it may be a relative of the extant mooneyes (Hiodontidae). An indeterminate hiodontid specimen (found alongside the Raptorex holotype) from the Nemegt Formation of Mongolia was found to share close similarities with both Hiodon and Coriops.[4][5][6]
The wide distribution of Coriops in the North American interior, its disappearance and reappearance in southern regions such as Utah, and its general higher abundance in high latitude formations over lower latitude ones, suggests that it may have been a northernly-distributed species whose range repeatedly expanded south during cooler climactic intervals.[4][5][11]
^Newbrey, M. G.; Brinkman, D. B.; Winkler, D. A.; Freedman, E. A.; Neuman, A. G.; Fowler, D. W.; Woodward, H. N. (2013). "Teleost centrum and jaw elements from the Upper Cretaceous Nemegt Formation (Campanian-Maastrichtian) of Mongolia and a re-identification of the fish centrum found with the theropod Raptorex kreigsteini". In Arratia, G.; Schultze, H.-S.; Wilson, M. V. H. (eds.). Mesozoic Fishes 5 – Global Diversity and Evolution. Verlag Dr. Friedrich Pfeil. pp. 291−303. ISBN978-3-89937-159-8.