古巨蜥是岛上居住在复杂洞穴网络的最大生物之一。它能达到三米长，并且它能轻松利用自己爪子的钢铁般的抓力在洞壁上垂直走动。 幸运的是，古巨蜥的大小使得它无法在任何人面前隐藏自己。但不幸的是对于洞穴勘探者，它依然是一种好战又危险的生物。 就像其他巨蜥科生物那样，古巨蜥是一种能分泌毒液的生物。它的毒药效果较慢，但它会至死方休地吸干被害者的有效力量和生命值，除非用一种罕见的解药才能治愈。 也就是说，通常古巨蜥的猎物在它们被这长效毒药压垮之前就会被撕碎。
Common name: Megalania
Species: Megalania muruspede
Time: Late Holocene
Megalania muruspede is among the largest creatures found throughout the Island's complicated cave networks. Reaching up to three meters long, it can traverse vertically up cave walls with little difficulty thanks to its powerful claws. Fortunately, Megalania's size means it is unlikely to sneak up on anyone. Unfortunately for spelunkers, it is an aggressive and dangerous creature nonetheless. Like other Varanidae, Megalania is a venomous creature. Its poison is slow-acting, but will drain the victim's effective strength and health until death unless cured by a rare antidote. That said, the Megalania's prey are usually ripped apart well before they succumb to the poison's long-term effects.
The rare ability of Megalania to effortlessly climb sheer environmental walls makes it a highly sought-after mount. While it is by no means the fastest, strongest, or toughest mount, the manner in which it can effortlessly scale mountains, clamber up barricades, hide in trees or upside-down, ensures it will always have place in any tribe's stables!