Genus Cheilophis Gilmore, 1938 TYPE SPECIES. — Cheilophis huerfanoensis Gilmore, 1938. EMENDED DIAGNOSIS. — Cheilophis can be differentiated from all other snakes by its unique combination of features: wide haemal keel (on the posterior mid- and posterior trunk vertebrae) that bears a constriction at around its mid-length and becomes wider and blunt wedged-shaped at its posterior termination; distinct “notches” of the haemal keel in ventral view; ventral expansion of the haemal keel in lateral view; thick neural spine that is mostly confined at the posterior portion of the neural arch; relatively thin zygosphene with a distinct median lamina (“lip”) and prominent lateral lobes; moderately vaulted neural arch; deep posterior median notch of the neural arch; deep interzygapophyseal constriction; almost circular cotyle and condyle; widely extended parapophyseal process of the paradiapophyses; almost horizontal to only slightly dorsally inclined prezygapophyses; and large prezygapophyseal and postzygapophyseal articular facets. In addition to these vertebral characters, Rage (1984b) also indicated the following cranial features as diagnostic for the genus: palatal process of the maxilla directed backwards; surangular lamina of the compound bone higher than the prearticular; coronoid present.

Published as part of Georgalis, Georgios L. & Mennecart, Bastien, 2025, Another wanderer from the Paleocene-Eocene Thermal Maximum? A new species of the North American snake genus Cheilophis Gilmore, 1938 from the early Eocene of France, pp. 317-331 in Comptes Rendus Palevol 24 (16) on page 319, DOI: 10.5852/cr-palevol2025v24a16, http://zenodo.org/record/15730159