Dinilysia (meaning "terrible ilysia") is an extinct genus of snake from the Late Cretaceous (Coniacian) of South America.

[2] Once the fossil of the snake was discovered, an x-ray computed tomography was used to build a digitized endocast of its inner ear.

[2] Due to a spherical vestibule, the Dinilysia patagonica was a species especially sensitive to low-frequency ground vibrations rather than airborne frequencies.

This discovery also extends its evidence to the fact that a burrowing habit predates the lineages of modern snakes.

In terms of the locality and age of the Dinilysia the fossils can typically be found in abundance in sandstone sediments favored to the Anacleto formation.

Additionally, the overall morphological similarities between that of D. patagonica has been used to determine the phylogeny and possible relations of the characteristics which other more present snakes may share.

[citation needed] There are numerous resources for evidence of the morphological characteristics of D. patagonica, including a full medium sized skull of D. patagonica which also has the posterior brain, the vessels, the cranial nerves, the inner ear, as well as the semicircular canals of the skull structure: which have all been naturally endocranially cast, which has been recorded as the first natural endocranial casting of an extinct snake species.