Dragon (Middle-earth) - Taxonomy

Taxonomy

Tolkien designed his own taxonomic system for dragons, based on locomotion and fire-breathing.

Some dragons (Glaurung) walk on four legs, like Komodo dragons or other lizards. Other dragons (Ancalagon, Smaug) can both walk on four legs and fly using wings. Winged dragons are first witnessed during the War of Wrath, the battle that ended the First Age.

Dragons who can breathe fire were called Urulóki (singular Urulokë), "Fire-drakes". It is not entirely clear whether the term "Urulóki" referred only to the first dragons such as Glaurung that could breathe fire but were wingless, or to any dragon that could breathe fire, and thus include Smaug. In Appendix A of The Lord of the Rings Tolkien mentions a "Cold-drake". It is commonly assumed, though not directly stated, that this term indicates a dragon which cannot breathe fire, rather than one who breathes ice or snow. Further, Tolkien calls a fire-breathing dragon in the non-Middle-earth story Farmer Giles of Ham a "hot" one.

Tolkien calls the dragon Scatha a "long-worm" but does not explicitly explain the term.