The following cladogram shows a possible phylogenetic position of Gengasaurus in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020).[6]
^ abIlaria Paparella; Erin E. Maxwell; Angelo Cipriani; Scilla Roncacè; Michael W. Caldwell (2017). "The first ophthalmosaurid ichthyosaur from the Upper Jurassic of the Umbrian–Marchean Apennines (Marche, Central Italy)". Geological Magazine. 154 (4): 837–858. Bibcode:2017GeoM..154..837P. doi:10.1017/S0016756816000455. S2CID132955874.
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Fastelli, C. & Nicosia, U. (1980). L'Ittiosauro di Genga (Ancona). In I vertebrati fossili italiani (eds Parisi, G. & Seppi, G.), pp. 95–101. Verona: Catalogo della Mostra.
^
De Marinis, G. & Nicosia, U. (2000). L'Ittiosauro di Genga. Castelferretti, Ancona: Cassa di Risparmio di Fabriano e Cupramontana Edizioni, 220 pp.
^Ilaria Paparella, Erin E. Maxwell, Angelo Cipriani, Scilla Roncacè and Michael W. Caldwell (2016) - The first ophthalmosaurid ichthyosaur from the Upper Jurassic of the Umbrian–Marchean Apennines (Marche, Central Italy). Geological Magazine (advance online publication)
^Nikolay G. Zverkov & Megan L. Jacobs (2021) [2020]. "Revision of Nannopterygius (Ichthyosauria: Ophthalmosauridae): reappraisal of the 'inaccessible' holotype resolves a taxonomic tangle and reveals an obscure ophthalmosaurid lineage with a wide distribution". Zoological Journal of the Linnean Society. 191 (1): 228–275. doi:10.1093/zoolinnean/zlaa028.