Wyrm

Wyrms are large, typically scaly reptiles with fore or hind limbs, a serpentine body plan, an emergent neocortex, many of which are avian.
Wyrms include serpents, cave wyrms, and redwyrms along with dracowyrms. 
Dracowyrms have scales and horns, an even further evolved neocortex, and can see in trichromatic vision.
A scaly wyrm has even more hardened scalium, metallic, or crystalline scales, beyond the hardness of natural keratin.