These snakes possess several unique features, including numerous small, spatulate, hinged maxillary teeth, a specialization that allows grasping and feeding on hard-bodied prey such as skinks, and the presence of fracture planes between caudal vertebrae that allow them to easily break parts of their tails in a fashion similar to many lizards (although they cannot regrow their tails).

Molecular data suggest that this pattern is caused by a late Eocene/Oligocene origin in Asia, followed by dispersal over the Bering land bridge to the New World.

Unlike other snake groups (e.g. Crotalinae, Colubrinae, Natricinae, Dipsadinae), however, sibynophiines evidently left no extant species in temperate North America.

The two genera likely last shared a common ancestor around 33 million years ago (95% HPD: 40.0–22.9 mya[6]), at which time all the continents were in or near their current relative positions and the climate in the Bering land bridge was warmer.

Less likely alternatives include dispersal over a Greenland–Faeroe land bridge, which was colder and probably had less suitable habitat for snakes at the time, or rafting from Southeast Asia to Central America, which, although not impossible, would be unprecedented among vertebrates.