Adriosaurus suessi (Seeley 1881) Late Cretaceous, ~95 mya, ~25 cm, wasn't a snake, but a close sister taxon. Derived from a sister to Ardeosaurus, Adriosaurus was a phylogenetic predecessor to the snake Pachyrhachis.

Distinct from Ardeosaurus, the skull of Adriosaurus was longer, as were the nares and nasals and premaxillary process. The postfrontal/postorbital contacted the prefrontal. The frontal and parietal were narrower. The sqauamosal was shorter. The teeth were longer. The coronoid process was taller.

The cervicals were smaller and more numerous as were the dorsals and caudals. The ribs were thicker (pachystotic). The dorsal ribs were shorter producing a more snake-like body.

The ilium was taller. The limbs were shorter. The metatarsals were subequal.

Palci A and Caldwell MW 2007. Vestigial forelimbs and axial elongation in a 95 million-year-old non-snake squamate. Journal of Vertebrate Paleontology 27 (1): 1-7. doi:10.1671/0272-4634(2007)27[1:VFAAEI]2.0.CO;2.

Caldwell MW and Palci A 2010. A new species of marine ophidiomorph lizard, Adriosaurus skrbinensis, from the Upper Cretaceous of Slovenia. Journal of Vertebrate Paleontology 30(3): 747-755. doi:10.1080/02724631003762963.

Seeley HG 1881. On remains of a small lizard from Neocomian rocks of Comen, near Trieste, preserved in the Geological Museum of the University of Vienna. Quarterly Journal of the Geological Society of London 37: 52-56.

wiki/Adriosaurus