Pachyophis is an extinct genus of Simoliophiidae snakes that were extant during the Cenomanian stage of the Late Cretaceous period.

More specifically, it was found to be from the Cenomanian Age about 93.9-100.5 million years ago in the suburb area of Bileca, Herzegovina.

[3] The family is characterized by the presence of hindlimbs and pelvic girdles, as seen in Pachyrhachis (one of the first discovered hind-limbed snakes).

Included in the most basal of snake relatives, Pachyophis in contrast does not have evidence of any form of limb preservation.

The holotype specimen was discovered in a quarry in an eastern suburb of Bileca known as Selišta, located in East Herzegovina 40 km inland from Dubrovnik.

Fossils of the area are generally from the Cenomanian-Turonian age, with Pachyophis being slightly younger found ranging in the mid to late Cenomanian layers.

[5] Pachyophis is considered a hind-limbed snake despite presence of any indication of forelimbs or shoulder girdle due to its other shared general morphology.

Other shared characteristics include a smaller head and distally straight ribs for a lateral compression of the trunk.

Its highest point reaches 2.1 mm (0.083 in) forming a blunt tip and concave posterior outline on the shorter edge.

This is representative of a suture and likely the location where the upper jawbone joins the premaxilla in the nasal opening region.

Their dentition show thecodont nature, their teeth fitted into bowl like alveoli lined on the jaw bones.

The enamel layer of the teeth is well developed with large, hollow pulp cavities possessing small openings leading into them.

At the anterior end, the neural arches are characteristically thin and shorter rising at an angle of 45 degrees post dorsally.

Scale repetition is defined in transverse rows, running parallel to one at notable right angles to the cervical vertebral column.

This likely means that the Pachyophis' would hold its head above its flat bodied stature, indicative of shallow water dwelling character.

[7][8] Pachyophis' narrowly tapered mouth and sharp backward pointing teeth indicates its carnivorous diet by action of gripping versus biting methods.

The jaw-teeth structure is designed for simultaneous grabbing and swallowing, fighting back against the forward pushing force of escaping prey.

The jaw's posterior elongation was also notably blocked from opening very wide, another usual characteristic of snake feeding mechanisms.