Dinilysia patagonicus (Smith-Woodward 1901) Coniacian, Late Cretaceous, ~88 mya, ~1.8 m in length was a large terrestrial snake that was derived from a sister to Pachyrhachis and was itself a sister to Boa (see below) and other extant terrestrial snakes, as also recovered by Zaher and Scanferia 2012. However they nested the burrowing snakes with Pachyrhachis, which was not recovered in the large reptile tree.
Zaher and Scanferia also reinterpreted the structures forming the otic region of Dinilysia, confirming the presence of a crista circumfenestralis, which represents an important derived ophidian synapomorphy.
Distinct from most snakes, the ventral margin of the maxilla was concave in Dinlysia. The dentary was more gracile. The rear of the skull was no wider than the trans-orbit width. The ribs were robust and so were the vertebrae.
The teeth were not preserved, but their roots were robust and closely spaced.