Ophidian

Vertebral structure is critical for the identification of fossil snakes, because vertebrae are among the most easily fossilized parts of ophidians.

Source: wiktionary

It has long been known that ophidians have lost not only their front legs but also every embryonic trace of these limbs and their associated shoulder girdle (to such a degree that we cannot determine how many cervical vertebrae they have).

Source: wiktionary

Siamese or double monsters are well known in saurians, chelonians, and ophidians, as are bicephalic, two-tailed and conjoined bodies (thoracodymus, ischiodymus, etc.).

Source: wiktionary

The ophidian beast began to glow eerily, and Aaron could discern a fine webwork of veins and capillaries running throughout the creature's body.

Source: wiktionary