The type and only currently accepted species E. leali is from the Late Cretaceous Lecho Formation at El Brete, Argentina.

[1] Another left shoulder and wing, almost complete and found associated in one lump of rock, as well as a few isolated bones were also assigned to this species mainly based on size.

E. leali was possibly fairly closely related to Avisaurus, another genus of probably carnivorous enantiornithines, though its exact relationship is unclear.

As no hindlimb elements are known from Enantiornis, it might include one of the El Brete enantiornithines known only from leg bones, namely Lectavis, Soroavisaurus or Yungavolucris.

[4] The cladogram below is from Wang et al., 2022:[5] Cruralispennia Protopteryx Elsornis Flexomornis Iberomesornis Longirostravis Rapaxavis Sinornis Enantiornis Halimornis Concornis Neuquenornis Eoalulavis Liaoningornis Gobipteryx Hebeiornis Eocathayornis Qiliania Intiornis Soroavisaurus Avisaurus Gettyia Mirarce Feitianius Longusunguis Dunhuangia Musivavis Pengornis Yuanchuavis Eopengornis Parapengornis Grabauornis Parvavis Cratoavis Gretcheniao Huoshanornis Shengjingornis Zhouornis Bohaiornis Eoenantiornis Fortunguavis Mystiornis Shenqiornis Sulcavis Key to letters: b = Boluochia c = Cathayornis e = Enantiophoenix f = Houornis h = Longipteryx i = Parabohaiornis j = Pterygornis l = Vorona m = Yuanjiawaornis n = Yungavolucris