|Final Fantasy X-2 Enemy|
- Normal: "A fiend that that sometimes attacks with Poison Fang and won't hesitate to use Stone Fang in a pinch. Watch out!"
Oversoul: "Now sporting a Darkness attack in its oversouled state. As an added bonus, it remembers how much damage it has taken when counterattacking."
The Archaeothyris is an enemy from Final Fantasy X-2. Its low Magic Defense and weakness to Ice make it an easy foe to deal with. However, be on guard with Softs as it can inflict Petrify, and carry lots of Antidotes as well to counteract Poison Fang.
In the Fiend Tale endings, a notable Archaeothyris was created from spirit of the know-it-all owner of the Blitzball Bar in Luca. Though he expected it to be closed since his passing, Archaeothyris finds his friends are running the tavern in his place. Departing to the Farplane, Archaeothyris gives a final lecture to his friends to care for the bar.
Archaeothyris was an amniote which lived 320 million years ago, in the Middle Carboniferous period. It is the oldest undisputed synapsid known. It was found in Nova Scotia, the same locality as Hylonomus, and Petrolacosaurus, all of which resemble Archaeothyris.